Biol 474 exam 3

marsupials

7 orders of marsupial, split into amerdelphia and australidelphia. Australidelphia is monophyletic and ameridelphia though to be paraphyletic. 3rd group from late cretaceous (deltatheroidea) outside extant marsupial grouping. Didelphimorphia and paucituberculata debated as basal group. Ameridelphia older dimermorphia opossums. Diverse from late cretaceous- middle cenzoic. Most lineages extinct by end of eocene were stem marsupials and not didelphimorphs. Opossums small, arboreal/semiarboreal, omnivores. Other Ameridelphians are pacituberculata, small, terrestrial, shrew like, carnivores and insectivores. Extinct groups of stem marsupials lived in SA in cenzoic. Borhyanoids formed a larger radiation of carnivorous forms (badger, dog, bear) Remaining SA marsupials is monito del mante. Arboreal, tiny, mouse like in mountains. Placed in own order (microbiotheria) more related to Australian marsupials. May be survivor of SA marsupials that migrated to Australia in cenzoic. Lineage is sister taxa to Australian marsupials, sometimes placed within cluster of Australian marsupials. Australdephians in 4 orders, largest group is diprotodontia, namedfor modified lower incisors (project forward), mostly herbivores and omnivores. MArsupial "lions" evolved carnicvory. 3 major radiatiosn within diprotodontia: phangeloids, vombatiforms, macropodoids. Phalangeroids are arboreal. Vombatiforms include koalas and wombats, specialized grazers with growing molars, extinct ones include marsupial lions. Macropodoids are hopping marsupials. Sthenarin are extinct one-toed browsing kangaroos, source of giant rabbit legends. Notoryctemophia included 2 species o fmarsupial moles that are sand swimmers. Paramelemorphia 3 families: bandicoots, bilbies, and pig footed bandicoot (extinct 1950s). Dasyulomorphia composed of carnivorous dasyalids: numbat, extinct thylacinids. Thylacine in island of tasmania.

Bird digestion

Absence of teeth keeps birds from processing food in mouth. Role taken by gastric apparatus. Birds gather more food than can be processed and hold excess in esophagus crop (enlarged portion of esophagus) for temporary storage and with folds that expand. Crop also transports food for nestlings. Length of intestine increases when plants are major part of diet. In doves, prolactin stimulates crop to produce food for young. (produced by fate-laden cells that detach fromepithelium and suspend in aqueous fluid) Carnivorous birds need larger stomachs for storage of large volumes of soft food. For insect/seed eaters require a muscular organ to contribute to mechanical breakdown. Gastric apparatus with 2 chambers: proventiculus (anterior glandular stomach) and gizzard (posterior muscular stomach), proventriculus large in species that swallow large items: contains glands to secrete digestive enzymes. Gizzard provides food storage during chemical digestion and mechanical processing of food. Muscular walls squeeze contents and small stones help grind food. Performs same function as teeth. Small intestine is principle site for chemical digestion. Break down food for absorption. Mucosa of small intestine in a series of folds (lamellae and villi) that increase surface area. Large intestine is short, passage through intestines is rapid. Food passage is slower in herbivores. Pair of ceca at junction of large and small intestines, small carnivorous bids and large herbivorous species. Symbiotic microorganisms ferment plant material. Birds have seasonal diet changes and gut morphology. Switch to plant material n winter= slower digestion and change in intestine length to accommodate. Digestive enzymes also change to match protein/fat reduction and increase in simple sugars. Cloural temporarily stores waste products while H2O reabsorbs. Precipitate nitrogenous waste in form of salts in uric acid. (good water conservation). Some species have extrarenal salt-secreting glands.

Africa and madagascar cenzoic radiation

Africa separated from SA late cretaceous, remain isolated until meeting Eurasia during oligocene and miocene, group of endemic mammals radiated in this period. Hypaxes (rodent like, but linked to elephants) were larger and more diverse than today, filling roles of antelopes and large pigs. Most african mammals arrived from Eurasia in Neocene. Fauna of africa and asia similar but different. Madagascar has fauna composed of entirely endemic species descend from small # of founding lineages. Madagascar part of Gondwana in middle triassic, but broke apart and became isolated in indian ocean. Present mammals appeared derived from africa in waves of dispersal. Lemurs (primates), tenfers (afrotheres), carnivorans (euplelids like mongooses), and rodents (nesomyids like rats and mice). Only rodents have representatives in africa. Lemurs and tenrers colonized in eocene, carnivorans and rodents in early miocene, little fossil record until late pleistocene. Lemurs- basal radiation of primates known from 5 extant and 3 extinc families used to have a greater diversity with gorilla sized lemurs (terestrial and arboreal). Extinction of giant lemurs soon after arrival of humans. Tenrecs took role of small omnivores and insectivores, cryptoprocta cerox, evolved to become cat like predator, but is more arboreal than true cats.

Bird movement outside of air

Ancestral bird condition is a foot with 4 toes. Coelurosaur ancestors were terrestrial runners. Became more arboreal as body size decreased. Tree perching early feature of bird evolution. Birds hop, walk, or run on ground. Sometimes also climb or wade. Hopping mostly found in perching birds (highly developed in passerines). May be only form of locomotion. Running is modification of walking, both feet off the ground at the same time for only a portion. Have long legs and small feet in fast runners. Long legs provide longer stride and reduction in foot weight allows more momentum. Reduces energy needed for change in momentum. Reducing toe #2 length lowers weight. Birds climb using feet, tail, beak, sometimes forelimbs. Tails can be used as support when foraging and legs climb. Tail prop/brace body pygostyle and caudal vertebrate in wood peckers are enlarged and support stiff tail feathers. Nuthatches climb on trunks and rocks in head upward and downward directions. They use claw on backward directed toe 1 (also strongly curved) 400 species are specialized for swimming and many can dive. Hindlimbs modified for foot=propelled surface swimming. Wider bodies also increase stability, dense plumage= buoyancy and insulation, large preen gland and structural feather modifications retard penetration of water to skin. Legs located at areas where weight interferes least with streamlining and can provide steering. Feet are webbed/lobed. (webbing acquired independently 4 times). Totipulmate (webbing of all 4 toes) found in pelicans and boobies. At start of power stroke (foot forward) web is parallel to H2O and moving downward (lifts and repels forward). Drag produced on dorsal web when web is perpendicular to water surface. Drag is major force propelling forward. Lobes on toes evolved convergently in several lineages. They are flexible. Flaps that flare open to present may surface on backward stroke and fold back during recovery stroke of foot moving forward. Grebes have lobes that don't fold back, rotate 3 and 4 toes 90 degrees to slice through water. Second toe located behind tarsometatarsus. Transfer to subsurface occurred by further specialization of a hindlimb already adapted for swimming of by modification of wing for use as a flipper. Foot propelled divers evolved independently in many families. Wing-propelled includes penguins (spenischiformes ) and auks (charadriiformes). Among water fowl are both foot-propelled an wing-propelled divers. (not as highly modified for diving)

Avian ovary

Avian ovary has different yolk follicles that grow at different times. 1 follicle starts growing, the next day a second follicle starts growing and so on. 1 egg in clutch is laid a day. amniotic eggs have pores to allow for gas exchange needed, but sometimes dangerous microbes can get in. Eggs need to be incubated to develop. A bird can incubate right away after laying first egg. So firs egg will hatch before the rest due to extra days of incubation, creates hatching asynchrony. A bird could also incubate after last egg is laid, so all eggs experience incubation simultaneously, thus eggs will also hatch at the same times. Most birds start incubation after most eggs are laid, offsetting the last couple of eggs. Typically pattern is that last laid egg hatchling is much smaller than the rest. Gives last hatchling a higher probability of death. Eggs are more exposed to possibility of harmful microbes the longer they are left unincubated. So they do a slightly delayed incubation to keep them safe from microbes and minimizes the effects of hatching delay. The more she lays, its harder to find sweet spot, ambient environment can also effect this. Tropical birds typically lay smaller clutches due to higher microbe risk. Birds in higher latitudes can lay more eggs in a clutch: latitudinal gradient. Due to interaction with incubation asynchrony and microbes.

Reproduction of birds

Avians only lay eggs and are oviparous. Constraints from flight specialization used to explain this. Except bats have flight and viviparity. Assumed to be ancestral system for archosaurs. Retention of eggs in oviducts of snakes and lizrds is key element in evolution of viviparity. Usually happens in cold climates so female can speed development. More control of temp. and development rate. Body temp. of birds is higher than brooding temp of eggs, may be too hot. Inoragnic eggshell is 98% CaCO3 (crystal calcite), embryo gains 80% of Ca2+ from eggshell. Organic protein and mucopolysaccharide matrix serve as support structure for CaCO3 growth.. Eggshell froms in infudibulum of oviduct. 2 membranes secreted to enclose yolk and albumen. carbohydrate and H2O added. Bird eggs are archetypal amniotic eggs. Innermost membrane (amnion) surrounds embryo. Outermost (chorian) encloses all embryonic structures. Allantois is highly vascularized and forms chorioaccantois (an chorion) for a site of gas exchange. Interior allantois is storage for waste. Nutrition provided by yolk (20-705 volume), enclosed in yolk sac and is gradually absorbed into embryo body, albumen provides H2O for development. Permeability of shell is a balance between H2O loss with loss of CO2 and gain of O2. pores occupy 0.02% of surface. Some pores are straight, some are branched. Eggshell becomes thinner as calcium is removed for bones, increasing gas diffusion. Bird eggs must lose water to hatch, embryo penetrates membrane of air cells with it's beak, ventilation of lungs starts to replace gas exchange. Crack formation happens 1/2 day after air cell penetration. Chick develops horny projection on beak (egg tooth) before hatching to help hatch. Disappear soon after. All birds have heterogametic sex chromosomes and have genetic0-determined sex. Female is the heterogametic sex and male is homogametic. (ZW, ZZ). W makes gonad secrete estrogen and stimulates ovary development. Male develops in absence of estrogen. Evolution of this sex determination unclear, crocodylians rely on temp. Females can have some influence on sex of offspring. Females lay one egg a day and may be able to adjust offspring sex in relation to laying sequence. Eggs laid first were one specific sex. Nestlings that hatch first are larger and grow faster, may relate to survival of specific sex based on body size. In some species a bigger female survives better.

bird characteristics

Birds are derived from theropod dinosaurs. 4 characteristics of birds: trunk that is held in a horizontal position with a shaft tail, highly modified forelimbs, hindlimbs with extensive fusion of bones and digitigrade foot posture, paedomorphic skull. furcula (wishbone)-fusion of clavicles traced to basal theropods. Component of flight mechanism, but widespread in all theropods. Postcranial pneumatization: airsacs in cervical and anterior dorsal vertebrae. Expansion of pneumatization to posterior dorsal vertebrae, ribs, and longs bones was independent in many lineages of theropods. (evolved independently of flight0 wrists: allow carpmetacarpus (outer wing) to bend inward to rest against ulna and radius when wing is folded. Extreme mobility from modifications of radiale and appeared in coelurosaurs long before evolution of wings/flight. ribs- bony projections (uncinate processes) extend up and back from each rib. Provide a mechanical advantage for respiratory muscles. Also seen in oviraptors and dromaeosaurs (nonavian theropods had flow-through ventilation)

bird reproduction

Birds have assembly line oviducts that successively surround a zygote with yolk, albumen, and hard shell. Most extant birds have a single functional ovary and oviduct produce fewer and larger eggs that are deposited one at a time, unlike what is thought to be the ancestral condition. eggs of extant birds have a narrow end and a blunt end. Fossils of non avian coeurosaur nests had eggs that were asymmetrical with blunt ends facing center of clutch. Egg shell analysis (revealed pigments protoporphylin and biverdin (blue-green) also found in bird eggs. Females deposited eggs in pairs within a circular depression constructed by adult fossil of a female with two eggs discovered. Parental care originated in nonavian dinosaurs, uniparental care by male is characteristic of coelurosaurs and ancestral for birds (ostriches) show this. Biparental care of most extant birds is a derived character of neognathae.

bird endothermy

Birds use shivering and non-shivering thermogenesis for heat production. shivering: muscle contractions to turn ATP into heat. Heat released in muscle and spread through circulation. non-shivering: increase in oxidative phosphorylation achieved by short circuiting a cellular process. (increasing proton leak in electron transport chain increases oxidative phosphorylation without synthesizing ATP). Basal proton leak accounts for 20-30% of resting metabolism is from permeability of mitochondria membrane and is constant. Inducible proton leak is produced by uncoupling proteins and increase the permeability of the mitochondrial membrane. Mammal UPCs in brown fat and skeletal muscle. Bird UPC are specific UPC is signaled by nervous system. Sarcoplasmic reticulum is second site of non-shivering thermogenesis. Colipin protein increases its permeability and allows Ca2+ to leak out to increase oxidative phosphorylation.

Cenzoic mammals

Cenzoic called age of mammale (meozoic mammals 2/3 mammalian history). New body forms never seen: swimming, digging, gliding, and wide diet range. Mammals branched into a wide range of sizes in cenzoic. Size and diversity of mammals effected by plant diversification. mesozoic: initial radiation of mammals in jurassic. Second radiation in early cretaceous. Mammals occurred at these two radiations independently with both evolving complex types of cheek teeth. Jurassic had monotremes (gindwana) and therians (eurasia). Rodent like multituberculates very important. Harmiyida stem mammals are important as an early radiation of omnivorous and herbivorous mammals, some probably arboreal of specialized gliders. Haramixids once thought related to multituberculates, but middle ear and shoulder girdle places them more basal that haramixid. In jurassic, emergence of mammalian middle ear, dentition, shoulder girdle. Earliest fossils are monotremes from early cretaceous. Very fast diversification in jurassic. Early cretaceous radiation much slower. Featured true therians and derived multituberculates. JAw and tooth studies show changes in diet (omnivore-herbivore) most therians became insectivorous and carnivorous. So marsupials became more herbivorous. Changes coincide with increase in angiosperm flora. (Mainly insect pollinated). Gave rise to higher insect, thus mammal diversity. Mammalians were affected by end-cretaceous extinctions (what killed dinosaurs), but rapidly recovered. Mammals started to radiate into greater diversity of diets and body sizes millions of years into cenzoic. Fossil record suggests radiation of extant mammals only happened in cenzoic, molecular evidence suggests it started in cretaceous. Current consensus is that initial diversification of extant mammal orders started during last few million years of cretaceous, but main diversification occurred primarily in cenzoic.

Dinosaur thermoregulation

Confusion around this subject: especially with feather discovery. Relationship between high metabolic rates and high body temp. is not applicable to dinosaurs. Dinosaurs are way too big for body temp, and thermoregulatory mechanisms linked to body size. Gigantothermy: thermoregulation in large animals with low metabolic rate and high body temp. lose heat to environment slowly. Would have allowed dinos to maintain stable core body temp. with low metabolic rates. Feathers not necessary for thermoregulation, Bodies of large dinos were scaled (shown from skin imprints. Small dinosaurs at high latitudes would have needed metabolic heat production and feathers. Dramatic decrease in body size during bird evolution: were feathered with high metabolic rates.

Herding or ornithschians

Discoveries of fossil beds of ornithischian supposrts hypothesis that they formed herds. material surrounding fossils usually comes from one fatal event (lived and dies together)ally comes from one fatal event (lived and dies together) ceratopsians: horns and frill elements of social behavior (male-male competition). Antelope with small horns engage in side one displays with other males to compete. deer with large antlers engage head on (triceratops). Moose with enormous antlers and flat surfaces face off head on (large antler=better). Nasal brow horns were weapons for defense may form herd shelter (rings in defense) Pachycephalasuars: used domed heads in male-male territorial combat. hadrosaurs: enlarged nasal regions, heads crowned by hollow crests and sexually dimorphic. Air in crests flowed from internal nares backward, probably used for visual display and vocalizations. They would have been able to hear sound from air in nasal passages. Many nests of non avian dinosaurs have been discovered. Ornithischian dinosaurs laid eggs in excavation filled with rotting vegetation to provide head and moisture. Some provided extended period or parental care. Many hatchlings found in one area. Possible creche behavior as well, like crocodylians.

Bird flight evolution

Dromaeosaurs had bird like characters: wrist structure for sideways flexion while rotating them. (also called maniraptora) birds use the same wrist motion to produce flow of air over primaries (outermost wing feathers). Evolutionary changes of birds took a step by step format in a mosaic evolution. Proavians were terrestrial predators with long legs for pursuit. Enhanced agility is a plausible hypothesis for advantage gained by winged proavians. from the trees down: ability to glide evolved many times in vertebrates and is a possible starting point for the evolution of powered flight. Small proavians were probably capable of climbing trees (arboreal). Proavian ambush may have used wings to steer as it swooped down on prey. They could have also glided from one tree to another while foraging for prey to avoid descending. (shown from early cretaceous proavian with feathers on all 4 limbs and tail). Although feathers lacked barbule and would not have been able to glide. May have been ground-dweller with feathers for social display. from the ground up: Strong carsotial (running) morphology of proavian suggest terrestrial locomotion flight origin. May have combined upward leap with wing flapping to swat and insect to ground (no birds do this.). Wing-assisted incline running could also be possible. Birds flap wings while going up a slope to assist climb. Weakness: shoulder joint prevented humerus from lifting higher than back, and out rules a downward wingbeat (high flapping only seen in ornithoraces)

Earky mammals and cynodonts jaw/teeth

Earliest mammals had dentary-squamosal jaw joint with ball like projection on dentary, teeth that occluded precisely and replaced once in a lifetime., prismatic enamel in teeth, molars with divided roots. Tinier than cynodonts. Oldest ones in late triassic- early jurassic. Possible olest one had an isolated braincase and mammal like promontorium. "mammalia" is crown group, "mammaliformes" is crown group and stem mammals, "mammaliamorph" is mammaliaforme and most derived cynodonts. Some features of soft tissue for early mammals can be deduced by monotremes. monotremes lay eggs, which is a generalized amniote condition, so early mammals were probably egg-layers. Defining features of mammals are hair and mammary glands. Some evidence of hair in late permian therapsids. Paleoneurology and gene function allow inference of both features. Endocasts (brain impressions) show enlarged cerebellum and ossified skull top and loss of pineal eye. These features also control development of hair and mammary glands. Cynodonts had high metabolic growth rates, (minima: mammal condition), monotremes have low metabolic rates and aren't good at evaporative cooling: probably like early mammals. Possession of maxilloturbinate bone sin cynodonts cited as evidence of endothermy, but for that to function that way, it needs separation of oral and nasal passages. Bone anatomy suggests that separation via muscles and soft palate wasn't present. Present when turbinates become ossifies in mammals. Trityodont cynodonts had indeterminate growth. This became determinate growth in early stem mammal (molganarodon). Epiphyses on long bones reflect determinate growth of mammals. They separated from shaft of long bone via a zone of growth cartilage in immature mammals, at maturity ossification centers on bone shaft fuse, epiphyses no longer appear as distinct structures. In all mammals, dermal bones from skull rood grew down around brain and enclose brain case. Earliest mammals would retain semi-sprawling posture as seen in generalized extant mammals. Mammals have a derived crurotarsal joint. Mammals and cynodonts have rod-shaped ilium, reduction of pubis, extension of pubis called epipubic bones, they are important for attachment of postural abdominal muscles. Lumbar vetebrae of cynodonts lacked zygophyseal articulations that allow dorsoventral flexion in extant mammals. Mammal lumbars have large transverse processes for attachment of longissimus dorsi to enhance dorsoventral movement during locomotion. Ability to twist spine may relate to laying down on side. May be important for suckling. General mammalian tooth condition is diphyodonty (only replaces once). determinate growth is essential character of this, teeth would replace continuously if head continued to grow. In cynodonts, teeth in both jaws were some distance apart, chewing was up and down with scissor like closure. Teeth in lower jaw were closer together in early mammals, chewing on one side of jaw at a time. Cynodont postcanines replaced continuously unlike mammals with premolars and molars. Mammals have precise occlusion possible by interlocking arrangement of upper and lower teeth. Only mammals masticate (thoroughly chew) in this fashion. Basal mammalian molar had 3 main cusps in a straight line. Derived early mammals, the middle cusp shifted to make teeth more triangular, upper tooth pointed inward and lower pointed outward, longer sides increased area available for shearing. Therian mammals have tribosphenic molars with multiple shearing crests, near cusp (protocone) in upper molars and occluded with busined talonid in lower molars. Adds function of crushing and punching.

monotremes

Egg laying mammals. Single opening of excretory and reproductive tracts. Ditremata in therains referrred to the separate openings. 2 extant monotreme families. ornithorhynchidae: platypus, semi aquatic animal thaat feeds on aquatic invertebrates. Tachyglossidae: short-beaked echidna.eats ants and termites, 3 species: zaglossus, only in new guinea and eat earthworms. Teeth from cretarous, early monotremes were 1/2 the size of extant ones. Cenzoic monotreme fossils only represent echidna and platypuses, fairly limited monotreme diversity. Platypuses and echidna not relics of a once larger radiation, but its main stay. Teeth and femur fragments show evidence of monotremes outside Australia, Molecular data show recent split of echidnas from platypus, may have originated from semiaquatic lineage and became more terrestrial (supported by aquatic ressembling myoglobin) Semi-sprawling stance like more generalized amnotes. Possibly specialized for swimming and digging. Elbow joint like cynodonts. Monotremes lack teeth as adults, have leathery bill, beak has receptors for electromagnetic signals. Bills differ greatly from bird beaks, miocene platypus obdurodon retain teeth with smaller infraorbital canal in skull. Enlarged infraorbital nerve ,may suggest better electrosensation and lack of teeth, nerve occupies space for upper roots of teeth. Spermatozoa of platypus is thread like, like birds. Shows basal amniote features retained in monotremes and birds. Male monotremes have spur on hindleg attached to venom gland to poison predators. Similar spur in some mesozoic mammals. Venom is rare among mammals.

endotherms

Endotherms match rate of heat production to that of heat loss. oxidative phosphorylation: more than 1/2 of energy in bonds released as heat. insulation: retards loss of heat to environment, can adjust insulation to modify rate. evaporation of water: cooling mechanism, only works when H2O available. normothermial: normal body temp. Varies a bit between different mammals and birds, but most conform to a generalized diagram. Endotherm usually in conditions where temps. are lower than body temps. adjusting and fluffing insulation allows for the same resting metabolism, even as temp. falls. Lower critical temperature: point where an animal has to increase metabolic rate to balance heat loss. Body size is most important determinant of LCT. It's lower in birds than most mammals, but there is always a point no matter when they have to increase heat production to maintain body temp. Whole-body metabolism: heat production is the sum of heat production in all of the different tissues and organs in an organism and the mass specific basal metabolic rates of these tissues vary widely. Cat rest, heart and kidneys are most active. In cold environments. insulation: reduces heat loss by trapping air. Animals can increase it by raising hair/feathers to increase thickness of trapped air layer. Heat loss increased by lowering insulation layer. Also increases by redirecting peripheral blood circulation to skin (especially in those with large surface areas) evaporative cooling: skin is permeable to water loss, baseline evaporation is insensible water loss. Water can also be evaporated by sweating/panting. Sweating requires little energy, but cools skin surface, but has minimal effect. Panting/gular fluttering cool internally, but require muscular activity (which adds heat) Hair length effects how good of an insulator it is- hair is longer gives better insulation, but insulator value of tropical creatures with short hair have some value as artic animals with short hair. Pellage also affects insulative value. Long haired tropical less insulation than long haired artic. Fully aquatic animals use blubber for insulation rather than hair, because insulation with hair plummets when it's wet.

cynodonts and endothermy

Evidence from bone O2 isotope composition suggest degree of endothermy in eucynodonts, and bone microanatomy infers convergent degree of endothermy in derived dicynodonts. Maxilloturbinate bones evolved convergently in cynodont and dicynodont lineages. Changes in anatomy that may reflect changes in metabolic rate (evolution of endothermy): Larger fenestra with increased tendency to enclose brain case with dermal bone indicate greater volume of jaw musculature and more food eaten in a day. In mammals and derived cynodonts, loss of postorbital bar show further jaw muscle enlargement. Distinct zygomatic arch with depression on dentary indicates masseter muscle originating here and implying more effective food processing. Reduced postdentary bones and new jaw joint with expanded dentary indicate compromise between food processing and hearing. Greater specialization of dentition reflects more emphasis on food processing. Teeth became increasingly heterodont. Showing greater degree of food processing and metabolic rate. 2 sets of teeth in a lifetime in mammals is diphyodont. Mammals have double rooted molars, prismatic enamel (shared with cynodonts), and mastication with occlusion. Development of secondary palate, complete one in cynodonts and mammals. Helps bolster skull against stress in food processing and eating while breathing. More food processing. Upright posture indicated higher level of activity. Shown to some degree in all therapsids. Short toes also indicate use as levers. Changes in ankle joint in cynodonts and basal therapsids indicate increased use of hindfoot. Calcaneal heel and olecranon process first appeared in cynodonts. Ventral portions of limb girdle reduced with more weight support in limbs. Increase # of sacral vertebrae means greater transference of thrust from hindlegs. Mammals and cynodonts have reduced pubis and rod shaped ilium. Reduction of lumbar ribs indicate presence of diaphragm and higher respiration rate. toward extension of prezygophyses limited lateral undulation of body and dorsoventral flexion of lumbar spine appeared in mammals first. Shorten tail, loss of ventral processes on caudal vertebrae and trochanter on femur show importance of gluteal muscles for hindlimb retraction. Larger brain case and distinct protrusion (promontorium) on petrosal bone encloses inner ear. Houses cochlea. These changes indicate higher locomotor speed and endurance, rate of ventilation and energy intake (efficiency of processing food.) Could have been accompanied by increased metabolic rate and internal heat production. Shift from basal amniote to more mammal like. Cynodonts considered possible endotherms from microanatomy. Have densely packed vascular canals in bones suggesting small red blood cells like mammals. These are associated with endothermy and more rapid gas exchange.

early primates

First primates were arboreal in cenzoic forests. Humans are late appearing primates and complex social systems are typical of extant primates. All extant primates are crown primates (euprimates), which exclude stem primates (plesidapiforms). Typical modern feature includes presence of opposable digits to grasp substrate during arboreal locomotion. Also increase dexterity and manipulation of objects. Precision associated with claws flattened into compressed nails and presence of flesh pad on distal finger ends. This is fundamental for grooming and social bonding. Increase in encephalization quotient (brain size) in euprimates) associated with shift to frugivorous diet and visual system changes. Increase in orbit size and location of eyes to front of face. Eyes have stereoscopic vision (detect objects from background). Binocular vision for seeing cryptic fruits, pivotal group for seed distribution. Olfaction less important in primates, visually driven, reduction in nasal region. Genes related to odor detection no longer functional.

Bird homing

Homing pigeons can get back easier on sunny days and get more lost during over cast Hypothesized that they use sun as a compass, Shifting a birds internal cock can fool them about directions. This is because the sun is in different positions throughout the day. This only works on sunny days, they can still fly home during overcast. Second mechanism when sun isn't present is probably magnetic fields. A magnet on a birds head affects their homing during overcast. Polarized and UV light also give the birds additional cues. Could navigate by scent or visual landmarks. They can also detect low-frequency sounds (comes from waves and mountains). Shows there is a hierarchy to useful cues.

original hominoidea

Homminoidea orginally considered 3 families: hylobatidae (gibbons), pogidae (other apes) and hominidae (humans). Hylobatidae still valic. Molecular data shows that chimps are more related to humans than gorillas and orangutans. Groillas are more related to humans than oragutans. Molecular data shows that we diverged from great apes recently. Hominidae now includes great apes and humans. Subfamily hominae includes humans and chimps gorillas. Fossil relatives are in ponginae. Humans and immediate ancestors in homini. Hominids now called hominins. Molecular data gives hominid evolution timeline: Indicate split between apes and old world monkeys occurred during late oligocene. Suggests that hylobatidae and hominidae split 17 ma, panginae and homininae around 13 ma. Gorillas separated from chimps and human common ancestor between 10 and 8 ma. (separated into east and west populations 3 ma). Humans separated from common ancestor with chimps 6.6 ma (aridipithecus- first hominin fossil 5.8 ma). Chimps and homnins interbred until 6.3 ma and 2 chimp species separated 2.1-1.6 ma.

Cynodont middle ear.

In all gnathosomes, stapes articulates with otic capsule. Pelycosaurs retained condition of large quadrate attached to squamosal, large stapes played role in bracing back of skull and would have allowed hearing of low-frequency sounds. Derived sphenacodontids had a flange on reflected lamina on angular bone of lower jaw and probably originated as insertion for an enlarged ptergoideus muscle (jaw closing), but reflected lamina became smaller and curved to hold eardrum. In therapsids, stapes reduced in size, attachment of the quadrate to the squamosal became mobile, reflected lamina became larger and thinner. Suggest that chain of bones in middle ear now had role in sound conduction, but large size would have restricted to low-frequency. More derived synapsids would have needed greater stress on jaw joint for increased food intake of higher metabolism. This would have interfered with role of bones in hearing. Evolution of jaw in synapsids represent conflict between hearing and feeding. As long as articular and quadrate form primary jaw joint, no membranous eardrum could form. reflected lamina may have acted as a type of bony ear drum or support for connective tissue that helped transmit ow-frequency sounds. Depression on outside of dentary shows apparent masseter muscle in cynodonts. Masseter moves jaw laterally in mammals and holds it in a supportive sling. Original function could have been relieving jaw joint stresses with sling like action, resolving conflict between eating and hearing. In cynodonts dentary enlarged, accomodating all jaw muscle insertions. Reduce stress on postdentary bones, allowing them to become smaller and conduct sound. These bones were loose and wobbly in cynodont for role of vibrating auditory ossicles. Dentary bones also became smaller to hear higher frequencies. Mammalian manubrium of malleus provides support to tympanum. Mammalian ear bones don't grow from emryonic condition. Tritherodontid cynodont (diarthrognathus) is evolutionary intermediate. Has both ancestral and mammalian jaw joints (articular-quadrate and dentary-squamosal). Post dentary bones still in groove of lower jaw, air-filled middle ear cavity may be present. Earliest mammals retain middle ear bones attached to dentary in lower jaw, arrangement of these away from lower jaw gives greater sensitivity. Separation involves loss of meckel's cartilage. Mesozoic mammals had partial mammalian middle ear (PMME), bones were detached from lower jaw, but connection to dentary retained with meckel's cartilage. Determined by grooves in dentary, but no ear bones. PMME involve independently twice: monotremes and therians. Final transition to DMME occurred many times in mammalian lineages. All mammals start with middle ear bones attached to jaw, genetic basis for reabsorption of meckel's cartilage base don timing frees them. Not known why PMME- DMME happened.

locomotion of mammals

Long legs provide long lever for major locomotor muscles (triceps and gastrocnemius). This favors speed and allow long strides for rapid motion. Foot posture in cursorial mammals is digitigrade (standing on tiptoe) in carnivores and unguligrade (standing on point) in hoofed mammals. Elongation in distal portions of limb (radius, tibia, metapodials). distal phalanx of each foot is encased in hoof. muscles limited to proximal limb portion, reducing weight (no muscle below wrist or in ankle). No motion in foot at beginning of stride, must be accelerated to a speed greater than body as it moves forward. The lighter the limb, the less effort this is. Force of muscular contraction in upper limb transmitted to lower limb via long elastic tendons. Stretch with each stride to store and release elastic energy. Leg tendons of kangaroos obvious as elastic energy. All curosorial animals rely on energy storage in tendons (achilles tendon attached gastrocnemius to calcaneal). Lengthening tendons to increase stretch and recoil may be evolutionary reason for limb elongation. Cursorial modifications restrict motion to fore and aft plane, thrust on ground contributes to forward movements. Clavicle reduced or lost, wrist and ankle only move fore and aft, forelimb can't supinate. # of digits reduced to reduce foot weight (1 in carnivores, artodactyls a and 2 and 5, peissodactyls 1 and 5 or 2 and 4). Early cenzoic ungulates and carnivorans not highly cursorial, thought that evolution of longer legs and specializations came from predator-prey relationship. Carnivores could run faster with longer legs, causing selection for longer legged herbivores to run away. Fossil record doesn't support this. Cursorial ungulates known for much longer that cursorial carnivores. Ungulates probably evolved it first to make slower gaits more efficient. Cursorial adaptations in middle cenzoic, ungulates in more open habitats and have to forage farther for food each day. Speed became more valuable later with predators. Fossorial mammals dig, scratching at surface most common type. Scratch diggers have stout pelvis with sacral vertebrae involved in bracing hindlimbs. Some burrowers use "rotation-thrust" of forelimbs or dig with teeth. Digging limbs maximize power at expense of speed, unlike running limbs. Achieved in forelimb with long olecranon process and short forearm. Retain all 5 digits, tipped with stout claws to break substrate. Large projections on limb bones (enlarged acromion) for strong muscles that retract limb to originate.

Cynodont jaw

Loss of lumbar ribs said to make development of diaphragm, resolving conflict between roles of costal muscles in locomotion and breathing. This shift to fore-aft movement seen in cynodonts signals increased speed and endurance to support higher metabolic rates. Coughing, vomiting, defecating, puturation rely on diaphragm. Double occipital condyle seen in cynodonts, allow head to nod and developed shaking head between atlas and axis. Cynodonts had range of head motions similar to mammals dens process appeared in more derived ones. Extant mammal have a single bone in the lower jaw, dentary, and 3 boned middle ear. Mammalian ear more sensitive to high frequency sounds than other tetrapods. Original synapsid jaw was tooth baring dentary formed anterior half and postdentary bones were posterior half, jaw articulation via articular bone (lower jaw) and quadrate bone (skull) Cynodonts had enlarged dentary and decreased postdentary. Quadrate and stapes (hymandibular) became inner war. Condylar process of dentary grew back and contacted squamosal bone and corresponding articular depression (glenoid) formed in squamosal. This contact created dentary-squamosal jaw joint, became only joint in mammals. Bones of old jaw became middle ear (articular= malleus, quadrate = incus) these joined stapes. Originally assumed that stapes in mammals alone formed auditory ossicle to transmit vibrations, also assumed that earbones and jaw articulation was superior to other tetrapods, new jaw joint transformed single boned middle ear to 3 boned with leftovers. Problems with this are evidence that enclosed ear evolved separately in amphibians and amniotes, genomic evidence shows that ear drum and middle ear cavity are not homologous between mammals and amniotes. So why develop new jaw joint and 2 more middle ear bones when it was fine before. Could be a bas period of transition.

cenzoic extinctions

MOst known cenzoic extinction occurred at the end of pleistocene (30% of mammal genera). Extinction events in late eocene and miocene claimed similar numbers. Pleistocene (quaternary extinction) was extinction of megafauna. Terestrial and marine fauna less affected by pleistocene extinction. Glyptodonts (giant sloths) Late eocene extinction associated with fall in high latitude temp and environmental changes. Archaic mammals disappeared(also modern mammals adapted to rain forests). Early cenzoic amphibians and reptiles in high latitudes reduced. Late miocene extinction associated with global drying ad falling in high latitude temp. Major extinction of browsing mammals from habitat loss (savanna woodlands- open grassland), NA hit very hard because of northern position and inability of animals to migrate south. The main extinction occurred at end of last glacial period and define the boundary between pleistocene and holocene. (animals more vulnerable to extinction during warming from glacial period). Megafaunal extinction only occurred after last glaciation and could be due to spread of humans. (Overkill hypothesis) overlap of human and megafaunal fossils for thousands of years suggest main cause is climate change with final blow from humans. Stress from evidence of widespread fires could have also added to this extinction. Pleistocene climate change resulted in migrations and range shifts of many organisma.

Bird bones

Many bird bones are pneumatic with very light skull. Leg bones proportionally heavier than those of mammals. Weight of birds skeleton is similar to a mammal. Most weight is concentrated in hindlimbs. Skeleton is similar to coelurosaurs: center of gravity beneath wings, enlarged sternum, flying bird sternum was a keel for origin of pectoralis muscle and supracoracoideus muscle. (well developed in strong fliers). Scapula extend posteriorly above ribs and supported by coracoid fused to sternum. Clavicle provide additional bracing (can be fused at ventral ends to form furcula (wish bone)). Hindfoot elongated and mesotarsal ankle joint. (within tarsals). 5th toe lost, metatarsals fuse with distal tarsals to form tarsometatarsus. Walk with toes on ground and tarsometatarsus projecting up. Knee concealed in contour/feathers between femur and lower leg. Distal tibia fuses with proximal tarsals to make tibiotarsus (most of lower leg). Fibula reduced to splint bone.

Marsupials vs. placentals

Marsupials and placentals differ most in reproductive biology. Placentals also posses brown fats Projection of rear of dentary where pterygoideus muscle inserts bends inward in marsupials and straight in placentals. Nasal bones of marsupials in diamond shape posteriorly to meet frontal bones, rectangular in placentals. Jugal bone of marsupials extends into glenoid cavity, jugal in placentals ends before gm]lenoid cavity. Bones that form base of secondary palate support 2 fenestrae in marsupial, but are solid in placentals. Many placentals have auditory bulla around middle ear. Most marsupials lack this. Most placentals replace all teeth except molars, marsupials only replace last premolar. Marsupials have 5 incisors, one canine, 3 premolars, and 4 molars (5-1-3-5/4-1-3-4), placentals have (3-1-4-3/3-1-4-3). Humans have (2-1-2-2-3/2-1-2-2-3) Placental brain has corpus callosum to link cerebral hemispheres. Almost all marsupials have epipubic bones that project forward from the pelvis, now recognized as basal mammalian character retained in a few stem placentals, provide insertion for muscles that stiffen torso. Permit less independent movement of hindlimbs. Some quadropedal cursorial marsupials (extinct) lost these bones. Loss of bones in placentals explained by constraints they imposed on locomotion or interference that the rigid components of abdominal wall could cause with expansion during pregnancy. Plaventals have the patella (knee cap). Contained within tendon of qudriceps muscle. Marsupials have "patelloid" of fibrocartilage other than bone.

Marsupial evolution

Marsupials did not reach australia until early cenzoic. They reached NA from Asia late cretaceous and radiated small forms. Initial cenzoic diversification mainly in SA. Australia probably populated with those from SA moving across antartica, marsupial fossils from eocene found in western antartica. Modern data shows that Australian marsupials came from a single stock in SA. Once in australia they had long term isolation and filled many different adaptive zones. When humans arrived, there was a marsupial lion, (Thyruloleo). Large cats extant placental analogues of thylacoleo. Extant jaguars of similar size only feed on mammals half their size, reflecting extinction of large herbivorous mammals in central and SA at the end of pleistocene. Convergence seen among herbivores. Many placental herbivores have similar dietary habits. Vertebrates can't digest cellulose; herbivorous mammals rely on fermentative microorganisms in the digestive system to break down cell walls. Symbiotes located in stomach or cecum and large intestine. Gastric specialization of marsupials and placentals derived independents, anatomically different with similar function. Convergence seen among arboreal browsers. Koalas and lemurs have similar diets and behavior. Hindgut fermentors (occurs in cecum and large intestine) Insectivores have long pointed snouts, require little oral processing. Extreme convergence seen in insectivorous bark strippers. Tap feet on bark to detect echoes of insect chamber, incisors rip bark and tongue probes for insects, this behavior is the same in australian striped opossum and madagascar lemur aye-aye. Wood boring behavior analogous to wood pecker. Evidence that terrestrial placental (condylarth) dispersed to Australia with marsupials, but did not survive. Only Australian placental is bats in cenzoic. Rodents arrived by early pliocene, evolved into uique Australian forms. True mice and rats arrived in pleistocene, but had little effect on marsupials. Marsupial biggest threat from humans from asia, arrival of dogs, and introduction of domestic mammals.

Bird migration

Migration is widespread among birds. Paleartic species migrate often across the equator. Some migrate to breeding ranges. Many birds return to the same migratory stop over sites. Birds may be concentrated at high densities at certain points along their routes. Birds may replenish resources at stopovers and could avoid predators. Habitat destruction is a very serious problem for these birds losing their stopover sites. Energy cost of migration is offset by energy gained by moving to a different habitat. Normal food sources could be unavailable in winter. Other species may save energy by avoiding temp stress of northern winter. Perhaps breeding in high latitudes in the summer provide more time to forage than birds at equator (more resources and longer days). Migration of birds from southern hemisphere influenced by rain fall and aridity. Movement is nomadic instead of between specific breeding and non breeding ranges.

mammal eggs

Monotremes lay eggs, evolution of viviparity in therians, uterine glands that ad shell and other egg components. Mammalian embryos have 4 extraembryonic membranes. Some of these form he placenta in therians, which helps to secrete hormones to tell mother state of pregnancy. fusion of chorion with yolk form choriovitteline membrane. fusion of chorion with allantois makes chorioallatoic membrane. Amion surround embryo for protection. All mammals have corpus luteum in ovary from follicular cell that remain after egg is shed. Hormones secreted by it establish and maintain pregnancy. Feedback from placenta maintains its life and suppresses ovulation, extending gestation. Gestation in marsupials never exceeds a single estrus cycle. Young born early and fasten onto a nipple to receive nutrition from milk, not placenta. Some marsupials enclose offspring in a pouch. Marsupials have shorter gestation than placentals. Neonate monotremes altricial, but in marsupials head, shoulder and forelimbs are well-developed while pelvis, hindlimbs, and tail are not. This is associated wit post birth carwl to nipple. All placentals still require a period of lactation for antibodies and nutrition no matter how precocial.

Social behavior in birds

Most birds are active during the day and can be observed. Colors and plumage identify species, sex, and age. 3 pigment types: melanins: produce dark colors. (eumelanins: black, grey, dark brown. Phaeomelanins: reddish brown and tan.) caratenoids: fat-soluble responsible for red, orange, and yellow. (mostly gained through diet. Intensity can indicate mate fitness), porphyrins: metal-containing compounds (UV light gives red fluorescence. Destroyed by sunlight. Mostly seen in fresh plumage) Structural plumage color (purple, blue, green) result from air filled structures in cells on surface of feathers. Spacing of structures determines which colors are intensified. These can combine with pigments. Daylight scatters from these structures. 2 categories of sound in bird behavior: vocalization through syrinx (structure at junction of trachea and bronchi), may be a derived character of crown group birds; sonations are nonvocal sounds create by feathers together or air moving over feathers. Bird calls are simple an brief. Songs are long and complex. Usually associated with territoriality and reproduction. Controlled by song control regions (SCR in brain. Neural connection between SCR part and vocal muscle brain region form during song learning period. SCRs tend to be larger in males and have more neurons. Females in some species give only simple calls and engage in complex songs in others. SCRs in nonvocal females play a large role in species specific mate recognition. Bird songs consists of more notes with silent periods. Birds can change frequencies and often have more than one song type. Bird songs of a specific species can have regional dialects. Dialects passed down from generation to generation. They also have some individuality to recognize neighbors and intruders) Some birds make sounds of drumming or clapping by striking objects of the sound of air passing through feathers. Drumming could be aterritorial signal or advertise the presence of a male. Fluttering of primaries 6 and 7 in african broadbills make loud sounds. Some species have modified feathers with thickened or bent bases or rachii that vibrate during a display. Visual displays usually associated with songs. Postures that display colorful feathers. Male birds often more colorful than females. these features contribute to more reproductive fitness.

Na cenzoic radiation

NA fauna more distinct from Eurasia in cenzoic than today. Most of todays fauna came from eurasia over bering land bridge in pliocene and pleistocene. Exchange between NA and SA occurred early paleocene, but SA soon isolated from NA for much of cenzoic by seaway in anama. Large predator adaptive zone in SA was occupied by borhyaenoid metatherians (ste arsupials extinct). large herbivores taken by perisoodactyl related native ungulates (now extinct). Platyrrhine primates and caviomorph rodents unique to SA arrived from africa at end of eocene. SA fauna unique till connected to NA via ishmus of panama and great American brotic interchange occurred. General exchange with an intermittent land bridge happened in miocene. Significant exchange happened late pliocene. Northern glaciations dried and created "savannah corridor", which was favorable to large scale migration. Falling sea levels also increased land availability. More species went from NA to SA. Great american biotic interchange seen as competitive superiority of northern mammals. South American retained more equable habitats during periods of climatic stress due to most of it being on equator (fewer extinctions expected)

Bird young care

Nests protect eggs from physical stressed and from predators. Swifts use sticky secretions from buccal glands to cement material. Grebes build floating nests Some birds incubate right after egg is laid, others wait for a complete clutch. Better for eggs to hatch synchronously. Smaller siblings may serve as replacements, or facilitate growth of older siblings. Prolactin suppressed ovulation and induces brooding. Insulating properties of feathers are hard for transferring heat to eggs, prolactin stimulates brood patch formation. Blood vessels proliferate in dermals to double thickness and give a spongy texture. Not all birds form a brood patch. Temp of eggs in incubation usually between 33-37 degrees. Some species will leave nest for longs periods of time to forage. Eggs of these can withstand cold, just adds more time needed before eggs can hatch. Larger species tend to have longer incubation periods. High predation risk can add to rapid development. Species near the ground have shorter incubation due to predation. Synchronous hatching may be synchronized by clicking sounds from breathing in eggs, acceleration and retardation of development of individuals can be involved. Vocalizations can accelerate incubation of others or delay it. Ancestral condition:; eggs hatch into precocial young (could feed themselves at hatching) followed by a period of association between young and parents. Not all extant birds produce precocial young. Goes from altricial (naked and dependent on parents) to precocial. Altricial young are guarded and fed by parents at hatching. They respond to arrival of parent at nest by chirping and gaping mouths. Sight of open mouth appears to stimulate parent to feed it. Intensity of begging does not indicate hunger, could result from competition. Duration of parental care is variable. Larger species tend to be dependent longer. Some species lay eggs in nests of other species, leaving foster parents to raise chicks (brood parasite). Diverts resources from parents own chicks and can push hosts eggs out of nest. Some birds can recognize foreign eggs and remove them. Causes brood parasite eggs to look more similar to a hosts eggs.

therians and lactation/ sex determination

Only therians have nipples, but all mammals lactate. Mammary hairs (basal mammalian feature) present in monotremes and marsupials. Mammae develop from areola patches. Milk composition varies little during lactation period in placentals. In marsupials, mammary glands play big role in providing nutrients and change composition to ensure correct balance. Lactation is more costly and less efficient than use of placenta. Hypothesis that lactation came from common ancestor supported by comparison of casein genes. In monotremes, young obtain some nutrition from egg yolk and then milk after hatching. Reduction in yolk contribution reflected in loss of yolk producing genes. 3 such genes in amniotes, but only one is functional in monotremes. All developing therians nourished with placenta. Not functional vitellogenin genes, but pseudogenes remain. Some inactivation of these genes too place independently inn monotremes and therians. Mammalian sex determination is genetic. Female and male therians have XX or XY. They cause sexual dimorphies based on hormones produced. Monotreme has multiple sex chromosomes, but precise genetic mode of sex determination is unclear.

Pelycosaurs

Pelycosaurs and therapsids: 2 major groups of non mammalian synapsids. Pelycosaurs basal found in paleoequitorial latitudes in northern hemisphere. Therapsids found in higher latitudes in southern hemisphere (gondwana). late permian- early triassic. Presence of fibrolamellar bone in basal synapsids might indicate higher rate of bone growth (and a basal metabolic rate) than reptiles, although no endothermic. Pelycosaurs: first appear late carboniferous. Some had snails (snail backs). Includes ancestors of mammals and represent paraphyletic assemblage. Basically generalized amniotes, unlikely that they had scales (beta keratin for them no produced by synapsids) Had long feet and sprawling limb posture, lateral flexion of vertebral column reduced. Locomotion of synapsids more limb-based, less reliant on axial flexion. Retained parietal foramen for the pineal eye, indicate temp regulation from behavior. (lost in cynodonts and mammals). Posses gastralia bones in ventral abdominal wall to help respiration. Many were generalized carnivores; teeth can pierce and rip flesh. Herbivorous caseids and edaphosaurids had blunt teeth and expanded rib cage for large guts; heads small compared to body- indicate no chewing. Spehancodonts most derived pelycosaurs: large carnivore and sharp teeth. Enlarged tooth in maxillary and arched palate (fore runner to separation of nasal passages and mouth), flange on angular bone. Features all linking spenodonts to derived synapsids. Main feature of edaphosaurids and spenacodontids is elongation of neural spines in trunk to make pelycosaur sail. Evolved independently in the 2 lineages. Know this because sails absent from early members of both groups and differed in detailed structure. Evidence of spine breaking and healing indicate skin love ring. Those of males could be more colorful. Sails could be for temp control by increasing SA for blood to warm, but blood wouldn't have been sufficient enough in sails to transfer heat.

mammal lactation

The females of all mammals lactate, males- except for marsupials- have mammary glands, but do not normally lactate. Precursor to this method of feeding would be parental care. Fossils at basal pelycosaur suggest that parental care may be ancestral synapsid trait. Monotremes lay parchment shelled eggs that need moisture for gas exchange, so mammary glands could have kept it from drying. (protomammary glands could only secrete small amounts), could have also been used to protect eggs from microorganisms with antimicrobial properties, mammary glands probably evolved as innate immune system: microbial function preceded nutritional function. Selection would then lead to more copious and nutritional secretion. Monotremes produce milk, but lack nipples, probably same in early mammals. Monotreme young suck milk from associated hairs. An animal can by diphyodont only if it's fed milk early in life. With a liquid diet, the jaw could grow while it had less tooth need, permanent teeth could erupt in a near adult sized jaw. Lineage with precise occlusion and diphyodonty must first evolve lactation. Description of paleoneurology of cyodonts suggests they may have been first synapsids to develop mammary glands. Lactation allows offspring production to be separate from seasonal food supply. Mammals can store food as fat and convert to milk later. Allows female to not require male assistance to rear young. Lactation also allows young to be born at small body size. Ability to suckle is unique to mammals and related to changes in oral region that allow deglutination (method of swallowing). Use seal of epiglottis and tongue allow breathing and swallowing while suckling on nipple. Seal is lost when larynx shifts ventrally after childhood. Lactation and suckling evolution: dynophanty replaced polyphanty. Precise occlusion also evolved for mastication in mammals. Biproduct of dyophdanty, couldn't happen otherwise. Allows for ingestion of more food. This important for many mammals in order to obtain food and energy. In order to get by with one generation of teeth, it would need delayed emergence of teeth for when most jaw and skull growth occurred. This is made possible by first having evolution of lactation. Milk allows young to not need teeth in first period of growth. Lactation evolution could be from relieving individual from stressor of food supply.

Synapsid name

The name synapsid refers to the single fenestra in teh skull. Non-mammalian synapsids are not closely related to extant reptiles. Synapsids were first group of amniotes to radiate widely in terrestrial habitats. Most abundant terrestrial vertebrates during late carboniferous- permian. Early permian- early triassic they were top carnivores and herbivores. Most lineages dissapeared at end of triassic. Synapsid first radiation (pelycosaurs) and second (therapsids) in paleozoic. Third (mammals) were in triassic- cenzoic.

therian senses

Therians have a long cochlea, coiled and fitting in skull, that is capable of better pitch etermination, extent of coiling varies in marsupials and placentals. Pinna (external ear) helps determine direction, pinna and external auditory meatus concentrates sound from a very large area. Pinna unique to therians. Most mammals can move pinnae. Aquatic mammals reduced or lost pinna. Cetaceans use lower jaw to channel sound. Condition of rod dominated retinas and poor color vision evolved independently in monotremes and therians. 5 types of photosensitive molecules present in early synapsids. Loss of some opsins in synapsid lineage led to basic mammalian condition of dichromatism. (only opsins). all mammals have LWS opsin (red/green). Monotremes retain SWS2 opsin and therian retain SWS1. Convergent loss of one or the other in ancestor that had both, not as nocturnal as modern mammals. Anthropoid primates have good color vision and brain specialized for vision. Human trichromatic vision comes from duplication of LWS opsin into an L form and M form. Some marsupials independently mutated LWS and are trichromatic. Many nocturnal and aquatic mammals have lost SWS1 and corresponding ganed are monochromatic. RH1 is opsin for rods.

Cenzoic ecosystems

Today is cold and dry compared to cenzoic, and varied in habitats. Cenzoic covered in rainforests at start. Angiosperm dominated vegetation and microhabitats. New habitats in pliopleistocene: deserts, arctic taiga, tundra. latitudes found distinguished division on continents boosting diversity as well. Early cenzoic had tropical forests every where with broadleaf plants that could withstand 3 months of day and 3 months of night. Animals in high latitude turtles, crocodiles, mammals resembling primates, tapirs, and small hippos. Open-canopied forests with dense undergrowth appeared with larger mammals radiating. High/mid latitude rainforest in paleocene came with with high CO2. Mammals radiated rapidly at start of cenzoic, but many are extinct. (archaic mammals) large specialized predators with teeth indicate high-fiber herbivorous diet appeared late paleocene. Carnivora (dogs and cats) present in paleocene. Modern birds diversified at start of cenzoic. Many present day reptiles and amphibians originated late cretaceous/early cenzoic. Butterflies and moths appeared middle eocene. Cooler and drier climate after early cenzoic brought in temperate forests and seasonal changes late eocene. Tropical animals in high latitudes dispappeared. tropical forests near equator need no freezing temps. In neogene CO2 levels rose till middle miocene and declined. Extensive savannas appeared early miocene, high latitude grasslands turned into treeless prairies. Woodlands changed to grasslands in African tropics came with radiation of humans. Radiation of mammals in neogene reflected vegetational changes. large grazing mammals like elephants and antelopes evolved with grasslands along with large cats and dogs to prey on them. Diversification of modern rodents and small mammals may explain diversification of modern snakes. Large lizards appear late cenzoic (magarania). Modern birds of prey and social insects of grasslands diversity late cenzoic (ants).

crown group reptilia

all extant diapsids common ancestors. upper temporal arch composed of 3-pronged postorbital bone and 3-pronged squamosal, jugal, and quadratojugal form low arch (lost repeatedly in diapsid radiations) 2 groups of diapsids: lepidosauromorpha (lepidosaurs, ichthyosaurs, sarcopterygians) and archosaromorpha (turtles, crocodylians, birds, nonavain dinosaurs) 2 lineages of archosaurs: pseurdosuchia (crurotarsal joint that can twist sideways) and ornithodira (mesotarsal joint with straight line hinge)

pterosaur

appear late jurassic until cretaceous. Rhumphohynchoids basal pterosaurs: long tail stiffened by anterior projections, leaf shaped expansion at tail end. Pterosaurs were larger and lacked tails and teeth. Teeth reduced or absent, tail lost, sternum developed a keel for flight muscles, thoracic vertebrae fused, thin walled bones (postcranial pneumatization: development of open spaces in bone), eyes were large and olfactory areas were small, unidirectional air flow. Limbs large in relation to trunk. Formed by skin stiffened by internal fibers. Brachiopagium (primary wing: arm wing) supported by arm bones and elongated 4th finger. Pteroid attached to 4th finger to support a membrane. Uropatagium (tail wing) provide additional lift at body rear. Extended between hindlegs and limit independent movement. Walked quadropedally, uropatagium reduced in ramphorhynchoids for hopping gait, pterodactyloids stride. Aerodynamic tests/modeling show that pterosaurs can fly. How they took flight is debated: originally thought to launch from a cliff. more recently thought to be a bipedal running takeoff, both mechanical and aerodynamic arguments discredit that. Most likely a quadropedal leap allowed wing and hindlimb to act simultaneousl to produce launch speeds. Small species with short jaws small teeth: insectivorous. long jaws and pointed teeth: piscivorous. Several lineages combine long jaws with close teeth: fliter feeders. Azdarchids: very large could have been eye to eye with giraffe, terrestrial stalkes that foraged quadropedally, long necks seize prey (no extant analogues, but thought to be similar to ground hornbills). 2 types: gracile and robust. Gracil had long necks and light skulls. Robust had a short neck and heavier bill. Robust was capable of killing dinosaurs. Fossils show that skin was covered by hair like fuzz (pycnofibers). Provide insulation, colorful for species and sex recognition. many had crests on their heads which appeared early in evolution. Formed by bones or soft tissue or both. Crests grew as individuals matures and sexually dimorphic. Used for intraspecific interaction. Pterosaurs were oviparous with flexible shells. Appear to hatch in advanced development and could run and fly soon after. Pterosaurs diversified widely when birds first appeared and filled many adaptive zones. Evidence doesn't support hypothesis that competition with birds drove pterosaurs to extinction. Body form comparison indicate that they occupied different morphospaces. Appearance of birds did coincide with increase in pterosaur wingspan. This was also with appearance of pterodactyloids and phamphohynchoid disappearance. Birds and pterosaurs lived together for nearly 10 million years.

bird morphology

bird morphology is very uniform because of flight specialization. Flight gives birds a max body size, muscle power for take off increases by a factor of 2.25 for each doubling of body weight. Power out put is a fraction of muscular force and wingbeat frequency. Large birds require longer takeoff runs (have to run and flap to reach needed speed). Wandering albatross has largest wingspan of any extant bird. Flightless birds are spared constraints with flight, but don't reach mammal sizes. Structural uniformity of all birds: non are quadropedal, no horns/armor.

urban birds

birds are most conspicuous non-human vertebrates in urban areas. Could actually be beneficial (pigeons) Most birds in cities are native to the region surrounding it. Small diversity of birds in cities. Cities are more hospitable to omnivorous and granivorous birds. Architecture provide suitable nesting sites for cavity nesters. Barbados bull finches in urban areas are bolder and better problem solvers than their country cousins. Species that invade cities have larger brains in relation to body size. (greater adaptability?). DNA patterns of city birds are different from country birds. Urban bird diets are not as healthy. Low proportions of saturated fatty acids in yolks of urban great tits. have fewer and smaller offspring. Incidence of small brains increases with length of time and urban population has been established. Noise pollution in cities changed bird use of vocalizations. Bird vocalizations used to catch prey and warn of predators can be covered by the sounds of the city. They can detect prey and warning calls a lot less when near a road. Anthropogenic electromagnetic noise in cities disrupts magnetic compass orientation. So do artificial light and polarized light reflected from shiny surfaces. Some birds change vocalization timing to avoid noisy periods in order to advertise territory and attract mates. Some species would sing earlier in the morning. Changes in amplitude and frequency also used by birds whose song is within the frequency range of anthropogenic noise. Birds can also produce high frequency sounds at louder amplitudes than low frequencies. (change in frequency result from change in amplitude) High frequency calls may be less attractive to females. Urban males have to choose between being sexy or audible.

coratenoid pigments in bird wings

coratenoid pigments from certain plants are used by birds for red feather coloring. (males only) Coratenoids act as antioxidants which help to remove damaging oxygen biproducts of metabolism. Could improve health. Coratenoids thought to be rare in nature. Bright red plumage could signal to mates that he was able to get the rare berries and has better health. Females do prefer more brightly colored males. MAle advertises that he doesn't need carotenoids because he has great genes or has tehm in abundance.

diversification of diapsids

diapsids diversified after mass end-permian extinction. main diapsids (ichthyosaurs, placodonts, nothosaurs, pachpleurosaurs, pleisosauroids, and mesosaurs) first appearedin triassic and diversified into sharks, seals, sea lions, walruses, and toothed whales. On land crocodylomorphs and basal archosaurs were first to become predators. Crocodylomorphs diversified through mesozoic and cenzoic and were more abundant than dinosaurs in early cretaceous. Flying diapsids evolved twice. Pterosaurs in late triassic and birds in jurassic. Earliest dinosaurs in middle triassic, diverse in jurassic. 3 stages: initial appearance (235-228 Ma), then major radiation in middle/lat jurassic (174-168 Ma), then several pulses of diversification in cretaceous.

archsauria and dinosauria

dinosaurs and birds and crocodiles. diapsid skull and antorbital fenestration, orbit fenestration, triangular. laterally spread teeth, deep skulls, 4th trochanter on femur to bipedal locomotion (additional surface area and large muscle) dinosauria: ornithischia and sauroischia. Theropods originally sister groups in ornthoeridae and sauropoda are different.

structure and function of non-avian dinosaurs

dinosaurs originated from small terrestrial archosaurs. Some had hip changes (erect stance) for bipedal locomotion and articulation of ankle to mesotarsal joint, allowing hindfeet to be thrust back without twisting. Changes allowed for increased body size, but required additional pelvic changes. Dinosaur limbs were oriented vertically. Early tetropods: muscles from pubis insert on femur and protract leg, muscles on tail retracted leg. Plate like pelvis. Moving legs under body made these muscles shorter and less effective in femur. Reduce stride to shuffle because muscles are shorter and can only contract to 30% resting length. Dinosaurs moved muscle origins to make them longer. Saurichian (lizard hipped), pubis and ischium elongated. Pubis rotated anteriorly. Pubofemoral muscle ran from pubis to femur. Ornithischian (bird hipped) rotated pubis posteriorly to lie against ischium and muscles originated on ilium, Pubis extended anteriorly and provided and anterior origin for protractor muscles. Both changes produced hip articulations to allow legs to be verticle.

mesozoic lepidosaurs

dominated seas, terrestrial today. Rhynocephalial only lepidosauromorphs radiating on land. triassic ones were small insectivores with conical teeth. They were lizard like. Jurassic and early cretaceous were 1.5 M, variation of teeth (bladelike for cutting/slashing, long pointed for fishing, broad for crushing/grinding plants). Tuatara similar to mesozoic rhynocephalians (except reestablishment of lower arch), but had the highest rate of evolution in known vertebrates at molecular level. Lizards and snakes radiated in mesozoic (eat dinosaurs) greatest diversity in cenzoic. Ichthyosaurs most familiar of mesozoic aquatic diapsids. Basal ones retained lizard like body, but derived in jurassic. Had hypocercal tail with sharply bending vertebral column. Upper lobe made of stiff tissue. Dorsal fin of stiff tissue. Paddles extended by skin and connective tissue. Had both forelimbs and hindlimbs. Modified into paddles by hyperdactyly (addition of extra digits) and hyperphalangy (addition of bones to lengthen digits) Later developed carangiform locomotion. Jurassic high point of diversity. 1 family remained by late cretaceous. Disappeared 30 million years before end-cretaceous extinction. Fossils with embryos indicate viviparity. Had tail first birth like marine life. Most had large heads, long jaws, and sharp teeth. Ate cephalopods and fish. Thalattoarchon: 9M, 1.2 M skull, bladelike teeth, apex predator in middle triassic. Shustasaurus: short snouts, toothless, no hypobranchial apparatus, ram feeders. Derive ichthyosaurs had very large eyes supported by ring of sclerotic bones. Placodonts: least specialized main lepidosaurs, retaining characteristics of terrestrial ancestors, shallow water habitats in tethys sea. Short legs, feet as paddles, tall not laterally flattened (no swimming), broadened gastralia, polygonal bony plate covering. forward-projecting teeth: large flat maxillary teeth, enormous teeth on palatine. Placodus: proposed as an herbivore: like sea rows, that use anterior teeth to dislodge sea grass. Nothosaurs and pachypleurosaurs: elongated marine predators with laterally flattened tail and slender jaws with pointed teeth, pursuit predators. plesiosauroids: appeared in late triassic to end cretaceous. Elongated necks with head proportional to body. pliosaurs and plesiosaurs: derived. pliosaurs (long sulls and short necks) plesiosaurs (small head and long neck). Both types had rigid trunks and rowed trhough H2O with oar like limbs. Hyperphalangy increased paddle size. Nostrils located high on head. Pliosaurs: neck became shorter and paddles larger. Speedy swimmers to capture prey. Pleiosaurs: neck lengthened and paddles smaller, fed on bottom dwellers. Pleiosaurs were viviparous: found with embryo, produced single large offspring. mosasaurs: late cretaceous radiation of varanid lizards into shallow epicontinental seas. Early ones had body proportions like varanids and limbs ended in digits. Probably swam with lateral undulations. More derived ones had webbing. Hypocercal tail. Earliest 1 M, but increased in size. Teeth suggest radiation in many zones. Highly kinetic skulls and teeth for seizing prey. Probably ate what they could catch. Viviparous with litters of 4 or 5. Each 15% of body length. Born tail first, reducing drowning risk.

early birds

early colurosaurs were not very birdlike (long body, center of gravity near hindlegs, shallow trunk, long bony tail, claws on forelegs, full tooth set). Several bird like anatomical changes by early cretaceous (sinolis) Center of gravity shifted toward wings, bony tail shortened, fuse vertebrae at end of tail to form pygostyle. Less conspicuous was changes in strut like coracoids (help shoulder girdle resist pressure from chest and wing muscles) Several proavian lineages lived in late triassic- cretaceous. These were carnivores. Proavians and earliest birds were probably generalized predators, ate anything smaller. Beak shape and crop presence (enlarged esophagus for food storage) and fossilized stomach contents indicate later birds developed dietary specializations seen in extant birds. Role of birds in seed dispersals arrived around existence of see eating birds. Hawk like birds rare (absent in cretaceous. niche filled by pterosaurs)

endotherms and energy usage

endotherms use most consumed energy to keep themselves warm, but can inhabit very cold regions. Artic birds and mammals have lower critical temps. Tropical animal LCT's 20-30 at air temps. below these they have to create more metabolism. Arctic animal LCT is -40 to -70 and only show a small increase in metabolic rate when temp. is lower, this is due to thicker insulation of arctic animals. Small mammals buffer winter cold effects by reducing time spent outside shelter or by sharing a nest. Snow provides insulation to ground beneath it. Small animals forage beneath snow and go to insulated nests when done. SA:V ratio is so high in small animals that their thermal zones are narrow. They confine winter activity to sheltered microhabitats and spend less time outside. Nests are constructed underground and they form groups in them in winter. A group together has smaller SA:V ration, center is always warmer and groups will shift. Voles forage on different schedules and never leave nest empty. Fastest way to chill a drink is to put it in ice water. Chemical reaction when water evaporates. When water evaporates, an exothermic reaction occurs and pulls heat from the system to cool. Not good for desert organisms when water isn't readily available. Sweating not as effective as panting, only cools surface.

mammalian skin

epidermis varies in thickness, outer skin layer. Claws, nails, and hooves are made of keratin. Hair is also made of keratin; grows from evagination of epidermis called hair follicle; functions include insulation, camouflage, communicating, sensation. Vibrissa specialized hairs with touch receptors, mammalian hairs associate with NCC that induce mechanoreceptor formation. Pelage (fur): closely places hairs from multiple hair shafts. Insulating ability proportional to hair length, and density. Arrector pili muscles attach midway along hair shaft pull hairs erect to deepen trapped air layer. Cold. stimulates this via sympathetic nerves. This reaction also occurs in hairless mammals. Hair color depend son melanin injecting into forming hair. Hair wears and gets replaced, most mammals do this through molting. The need to evolve fur as insulation may have been present in small cynodonts and early mammals. Skin glands develop from epidermis, probably basal tetrapod condition reduced in tetrapods. 3 types of glands: sebaceous (produce oily serum to water proof hair and skin), eccrine (improve adhesion of tactile perception like on hands), and apocrine (secretions used in chemical communicating) Eccrine glands produce sweat, but very few mammals sweat. Other mammals involve evaporative cooling by other means. Many mammals have specialized scent glands (modified from sebaceous or apocrine) sebaceous will make volatile substances to release in the air. Many carnivorans have anal glands to deposit scents with feces. Apocrine glands in ear produce earwax. Mammary glands appear to be derived from basal apocrine glands because both use a similar mode of secretion (exocytosis)

feathers and birds

feather impressions in fossils show that feathers appeared long before birds. protofeathers: feather like structures found with theropod fossils (dinofuzz). Simple hollow filaments 1-5 cm long, if epidermal then they are protofeathers, if dermal then just skin parts. Fossil of coelusaur gives evidence for epidermal origin (filaments had enough organic material, showed B-keratin unique to feathers). More complex feathers of nonavian theropods had down like tufts of filaments and feathers with symmetrical vanes- locations varied among species (back limbs) protofeathers widely distributed among coeulosaurs. Probably used for species and sex determination, courtship displays, etc. Pannaceaus feathers and filaments on adult ornithomimus, but only filaments on juveniles. (central shaft with vane on each side. Suggests that adult feathers had social or reproductive functions. Melanosome shape and distribution studied to determine feather color, but bacterial decay could have led to soft tissue changes and maybe some things seen as pigment cells are actually bacteria. Although immunological tests prove the presence of melanosomes and keratin in some fossils. Early feathers could also provide insulation by keeping coelurosaurs warm at night while tucking away beak and feet. Could retain heat produced by resting metabolism and muscular activity heading towards endothermy. Different types of feathers have different functions and one bird can have multiple different types. Feather diversification resulted from extensive duplication and modification of beta-keratin genes. Evolution of feathers and flight were separate as seen by distribution of feathers in nonavians.

development of feathers

feathers development from follicles in skin arranged in pterylae (tracts) separated by apteria (unfeathered skin). Some birds lack pterylae and have feathers distributd uniformly. More than 90% of feathers are from a specific beta-keratin protein. 1% is lipids and 8% is water. Remaining is other proteins and melanin (pigment) Feather is anchored by calamus until molting. Long rachis extends from calamase ranges from round to square (cross section) which gives stiffness. (only in flight feathers, barbs project between branches from ranchis of veined feathers. Proximal/distal barbules branch from opposite sides of barbs. (ends of distal have hooks to attach to proximal) forms a flexible vein. Contour feather has soft barbules at base without hooks (called plumalaceous/downy) gives properties of thermal regulation. Further from base it forms a tight surface (vane). This part is exposed and serves as an air foil, protects under coat, sheds water, and absorbs solar radiation. 5 types of feathers: contours feathers: outer most feathers, remiges (wing) or rectrices (tail) are stiff and mostly pennaceous for flight. Distal portions separated by slots when wing extend slots reduce drag. asymmetric vaphs allow feather tips to twist. Semiplumes: intermediate between contour and down feathers. Large rachi with entirely pumalaceous vanes. Hidden beneath contour, provide insulation and stream line contours. Down feathers: various types are entirely plumalaceous; rachis short or absent. Provide insulation, powder ones become particles of keratin to waterproof contour feathers. Bristles: stiff rachis without barbs (or only proximal portions), around bill base. Screen out foreign particles, aid in insect capture, act as tactile sense organs. Filoplumes: fine with short barbs at tips and nerve endings in follicle walls (connect to pressure and vibration receptors), give info about position and movement of contour feathers. Helps to adjust feathers for flight, insulation, bathing, and displace. Fast flying birds have structural characteristics similar to fast flying aircrafts. Contour feathers make smooth junctions between wings and body or head and body, Elimination turbulence/resistance. Streamlining bettered by tucking in feet. Birds lack urinary bladders and many have one ovary. Gonads are usually small and hypertrophy during breeding. Males in most species lack phallus, all of this reduces body weight. Feathers existed long before flight, but flight modified them. Thermoregulation? not true for dinosaurs aren't endotherms. signaling? leading hypothesis.

evolved cetacean features

features evolved for cetaceans are diving, massive fat reserves (metabolic and thermoregulatory functions), changes in senses for underwater. These evolved features can be studied through genome. Myoglobin genes have improved O2 carrying ability in muscles, essential for divers used to establish aquatic origins for now terrestrial mammals. Further changes seen in diving specialist toothed whales. Changes in genes related to high frequency reception (especially those coding prestin for hair cells in cochlea) seen in echolocators Cetaceans have pseudogenes associated with sense changes. All lost color vision and opsin for short wave reception is nonfunctional. Occurred by different mechanism in toothed and baleen whales showing that common ancestor was dichromatic. Degeneration of olfaction and taste genes. Olfactory genes in toothed whales are pseudogenes and they even lack olfactory nerve and bulb in brain. Baleen whales reatain brain structures and have some functional olfactory genes. Cetaceans lack vomero nasal organ and have no taste buds. Fossil skulls show that vomero nasal organ was lost at protocetic cetaceans. Genes encoding for taste became pseudogenes for enamel production. All cetaceans lack hair, but have pseudogenes for hair production. Live adult bottlenose dolphin with hindlimbs caught by japanese dolphin hunters. Probably retain complement of genes for hind limb development, but are normally turned off.

kangaroo

female kangaroo doesn't help young make it's way to pouch, just licks a trail. unknown why. opportunity for a fitness test. If young has a serious problem, it might benefit your fitness to not put a lot of investment into young and can try again later- assessment shows fitness. young kangaroo drinks high fat milk with low protein. Joeys at earlier stage of development drink milk low in fat and high in protein- needs to grow a lot more. Both can exist at the same time to compete for parental resources. Compete at different stages of development. Most species don't do this. Kangaroos have embryonic diapause to suspend development in blastocyst triggered by suckling.

herbivore digestion

herbivores eat a lot of cellulose (cell wall) from plants. Tough and sturdy and no animal can digest it. Herbivores get nutrition from areas between cell walls. Cellulase needed to digest cellulose. Only produced in unicellular organisms. Herbivores have bacteria symbiotically living in gut to ferment and break down cellulose. Hindgut and foregut fermentation. Hindgut probably ancestral (horse and elephant), foregut (deer) Foregut fermentation: grass ground down and swallowed in multichamber gut that contains some bacteria to break down cellulose. Then cow regurgitates and chews it some more, ferment protein to go to liver which then becomes urea. Urea is used by bacteria to grow and populate. Surplus bacteria pass and become digested. All protein comes from bacteria and bacteria provide all nutrients needed. Foregut fermenters need to forage less than hindguts. Bacteria makes all essential amino acids, cow doesn't need to be as selective about diet. Problem is that it's slow, which restricts size of these animals. None are mall or large. Too energetically expensive for small animals. Hindgut fermentation: bacteria reside in modified portion of large intestine (cecum and colon). At this point, most of food has travelled past absorption surface, so it is fast, but animal doesn't get as much nutrition. Some engage in caprophage and eat own feces. This allows to take up extra nutrition. Tend to do better with high quantity over quality food.

evidence in opah lampris gattatus (fish) for whole body endothermy

internal temp profile: warm in colder water, as it swam freely they tracked change in water temp and fish internal temp. Even as water temp decreased, fish internal temp stayed similar. Possibly through counter-current heat exchange of gills. Tuna without this counter current mechanism can't go as deep as opah. Opahs can spend more time at greater depths: exploit new niches.

movement of head and precocial young

mammal trait is atlas-axis complex (C1 and C2), atlas with skull allows nodding. Atlas-axis allows side to side movement. Precocial young hatch at advanced stage of development (can walk and move). altricial young hatch at an earlier stage of development. Large carnivores tend to produce multiple altricial young. Herbivores tend toward single precocial young. Herbivores are prey or carnivores, precocial allows them to be more mobile and less vulnerable for a shorter period of time. Carnivores gain advantage of more gene pool with more young and altricial young are less energetically expensive. Also, no need to escape predators.

Mammalian adipose and heart

mammalian adipose tissue is important for insulation. Can also serve as a metabolic or cushioning role to many organs. Recent studies revealed that adipocytes secrete a variety of messenger molecules to coordinate metabolic processes. Some help with immune system. Brown fat in placentals mammals is specialized for thermogenesis, breakdown lipids to produce heat. Very important for thermoregulation in newborns. Mammalian heart is 4-chambered with complete septum and single systemic arch. (left) right is present in development. mammal erythrocytes lack nuclei. Monotremes retain small venosus as a distinct chamber in the heart, so was probably early mammal condition. This structure is incorporated into wall of left atrium as sinoatrial node in therians. Mammals also have platelets to aid in blood clotting (thrombi), but that can form in coronary vessels and cause heart attack. Adipose tissue in mammals is distributed all along body and has complex functions for more than energy storage. Secrete leptin to bind to brain to regulate appetite and food intake. As adipose increases so does leptin secretion. When leptin is knocked out, animal continues eating and become obese.

mammal groups

mammals are perceived as dominant terrestrial animals of cenzoic, but are smallest vertebrate lineage in terms of diversity 3 groups of mammalia: allotheria (multituberculates: extinct), prototheria (monotremes), and theria Theria divided into metatheria (marsupoials) and eutheria (placentals) Groups share reduction of amniote pterygoid flange to tiny f=projection pterygoid homulus, ossification of maxilloturbinate bones in nose, expansions of occipital condyles for head and neck articulation, loss of small bones from dermal skull roof, and lower jaw. Original metatherian- eutharian divergence in asia, earliest members of both groups found marsupials have placenta, just less extensive than placentals. Currently viewed in synapsids that multituberculates are more closely related to therians than monotremes. Extant monotremes are toothless as adults. Teeth of steropodon (early cretaceous) show teeth with triangular cusp arrangement, unlike less complex teeth of mesozoic mammals. These teeth place montreme sin southern radiation of mammals during mesozoic. (Austraosphenida). Other cenzoic mammals in northern radiation (boreaspenida). Multituberculata has a few long-lived families (late jurassic- middle cenzoic). Most were small. Narrow pelvis indicates viviparous birth to altricial young. Get name from broad and multicusped teeth specialized for glinding, indication herbivorous or omnivorous diet. Many had large blade like premolars possibly for seeds. Limbs abducted position seen in therians. Most were terrestrial, but some had prehensile tail and ankles to allow backward foot rotation. (arboreal). Many were probably like rodents. Extinction could be due to rodent competition starting late paleocene.

mammalian eating and facial muscles

mammals chew food to fine particles and swallow. mammalian tongue aids in swallowing and food processing. Coordinates manipulation by tongue with elevation of soft palate and constriction of pharynx to swallow. This process is unique to mammals called deglutination. Epiglottis blocks opening of trachea during swallowing probably appeared around evolution of posterior palate. Facial muscles are unique to extant mammals. Mobile lips may have been present in derived cynodonts. Probably first evolved in lips and cheeks to enable young to suckle. Thought to be homologous with neck constrictor muscles of amniotes. Muscle in lizards used to move full prey down esophagus. Since mammals chew, that muscle could assume a different function. All mammals with well developed facial muscles display similar expressions for similar emotions. Mammals have facial muscles, can make facial expressions for communication. Primates have extensive facial muscles for extensive facial expressions. Some mammals have specialized facial muscles for food storage.

mammals extinction

mammals exposed to habitat loss, harvesting for food, introduction of alien species, spread of disease, and trophy hunting. Horns of sheep and bovidae formed from a bony core covered by a keratinous sheath. Used for display and fighting and are permanent structures unlike deer, which shed them. Horn size key determinants of reproductive success and sexual selection. Study on ram horns show decrease in average size from selection pressure of trophy hunting. Set a horn length for "legal" rams at 80% full circle, but many rams have fast growing horns and are killed before mature. Trophy hunting created unnatural selective advantage for rams with slow growing horns. They reach a smaller max size. Recovery from unnatural selection is very slow. Value attached to rarity endangers even more, because they fetch higher prices. Endangered status is a draw for trophy hunters. Desirability increases as species become more rare. High revenue in countries for trophy hunting. Opposing view focuses on trophy species alone and not community. Many species benefit from conspecifics. Decline in population declines fitness of each individual. "anthropogenic allele effect: increased incentive of rarity ensures continued hunting that can reduce size of population until essential allele interactions no longer exist (extinction vortex). Certain characteristics increase extinction risk: large herbivores mature late and have low reproductive rates. prevent rapid repopulation. Large carnivores need a lot of space. Reduces chance of encounters when female is sexually receptive. High degree of sociality makes a species vulnerable to anthropogenic allele effect. Smaller packs lose more portions of kills to competitors.

Mammal lungs and bladder

mammals have large lobed lungs with finely branching bronchioles in each lung, ending in this-walled alveoli for gas exchange. Diaphragm aids ribs in inspiration and divides original vertebrae pleuroperitoneal cavity into peritoneal cavity (viscera) and paired pleural cavities (lungs) All mammals retain original tetrapod bladder, excrete liquid urine. mammals entirely lost renal portal system, elaboration of loop of Henle in kidney tubules allows mammals to excrete concentrated urine, Early mammals like monotremes with cloaca for excretory, reproductive, and alimentary opening.

mammal senses

mammals have larger brains than other vertebrates. More reliant on hearing and olfaction, less reliant on vision. Enlarged neocortex (area concerned with cognition). infolded cerebellum, large representation of area for cranial nerve VII (facial). Size and shape of brain can be determined by skull endocranial cavity. Endocast for cynodont shows similar sized brain to reptiles with better developed olfactor lobes and cerebellum. Large cerebellum consistent with mammals. Derived cynodonts had small cerebral hemispheres, not as complex or flexible behavior. Portions related to hearing and vision also relatively small. Most extant small mammals are nocturnal- probably early mammal condition. Mammals don't rely on vision as much and most lack good color discrimination. Animal retina dominated y rods for low light sensitivity and have only 2 cones (dichromatic). Cone require a higher light intensity that roods, so diurnal animals have a higher concentration of cones in rovea. Nocturnal mammals have more rods for night vision and have reflective tapetum lucidum to enhance vision more. Most nocturnal mammals have large eyes and varied orbit sizes in non-mammalian synapsids indicate nocturnal behavior evolved several times, most recently at tritylodontid cynodonts. Genes suggest for nocturnality took place after monotreme-therian divergence. Olfaction was always important in mammals probably related to nocturnal behavior. Humans have small olfactory lobes and few genes, correlated with capacity for color perception. Middle-ear bones of early mammals were smaller than cynodonts. Cochlea of early mammal was elongated over cynodont condition, but not as much as extant lineages or as coiled. Most therians have 2.5 coils. Coils allow structure to fit in skull. Monotreme cochleas are moderately elongated with 0.5 coils. This appears to have evolved independent of therians. Monotremes retain mucosa sensory structure at cochlea end present in amniotes and lack a pinna.

monogamy and polygamy in birds

monogamy and polygamy shown in social vertebrate mating systems. Monogamy is general social system of birds. Pairing may last for a season or a lifetime. Both parents usually participate in care of young. Eggs are incubated and young need to be fed some food. Oviparity may result in this parental care. Monogamy doesn't mean fidelity. Extra pair copulation is common. Some eggs in a nest may be fertilized by a different male. Social monogamy: male and female share responsibility for crutch, but show no fidelity. Genetic monogamy- male and female share responsibilities and have no extra-pair copulation.

mammal urination

monotremes use a cloaca for urinary, alimentary, and reproductive systems. In therians, alimentary and urogenital tracts have separate openings with perineum division. female primates have 3 independent openings. Male therians use urethra for urine and sperm. Other male amniotes use penis just for sperm. therians have hypaxial musculature for muscles in perineal area to control separate urogenital and alimentary openings. Monotremes reproductive tract has amniote condition, 2 separated oviducts that fuse at base and join urethra (urogenital sinus) oviducts swell to form 2 uteri, only left oviduct functional in platypus. In all therians, ureters draining kidney enter bladder rather than cloaca. In males vas deferentia loop around ureters passing to urethra. Oviducts in females fuse in midline, all placentals have a midline vagina, but only a few have a uterus. Most placentals have a bipartite uterus. (divided length wise into left and right)

morganurodon

oldest specimen known as mammal. Fossilization of nasal lacrimal duct. Also seen in extant mammals, secretions from lacrimal gland goes down this duct and is used to treat and condition pelage, suggesting presence of hair for mammals. This duct is not present in cyclodonts.

metriorhynchid crocodylomorphs

only succesful marine radiation of archosaurs in mesozoic. Appeared early jurassic through early cretaceous. Heads stream lined, air spaces in head made light skulls to allow floating at surface. Paddle like limbs, posterior vertebra turn sharply downward in hypocercal tail and upperlobe stiff tissue. Most were fish eater, dakosaurus and geosarus could kill prey larger than themselves. Bone crunching jaws in dakosaurus, blade like teeth in geosaurus. Probably employed crocodylian death roll.

Pangea breaks apart

pangea break up in jurassic began with NA opening ancestral atlantic ocean. Laurasia moved to higher latitudes in cenzoic. India collides with Eurasia. Gondwana formed first. Collision with india and eurasia created himalayas. All of this influenced cenzoic climates, uplift of mountain ranges led to altered rain fall patterns and spread of grass lands as a new habitat. SA, antartica, and australia separated from Africa in cretaceous, but maintained connections into early cenzoic. Africa separated from europe by tethys sea until the miocene, SA and NA had no connection until pleistocene. Australia drifted northward. Antartica had connection with SA until cenzoic. Arctic mammals a subsect on SA. New zealand separated from Australia late cretaceous, had diversity of endemic tetrapods. Only mammals are 2 bat species.

Bird muscles

pectoralis major and suprecoracoideus muscles (wing down stroke) originate on sternum keel and are 25% of body weight. Birds that use legs a lot, the weight of leg muscles can be 20%. Swimming bird muscle weight is evenly distributes between legs and wings. (30-60%). Terrestrial flightless birds have larger leg muscles than wings. Dark muscles in legs of high runners indicate myoglobin and high capacity for aerobic metabolism in leg muscles. Birds that only fly shortly to avoid predators use explosive take off fueled by anaerobic metabolic pathways and followed by long glide to ground. Strong fliers have dark breast muscles. 2 muscles for flight: supracoracoideus and pectoralis (strokes of humerus), opposing muscle actions on the same side of humerus, supracorcoideus tendon acts as a pulled to allow this. Both muscles attach to keel on sternum. Wing is cambered (convex and concave), air travels a greater distance to go over the wing, air on top has to travel faster and forms a vortex. Makes negative pressure on top and helps provide lift in comparison to positive pressure on bottom.

photo period and birds

photoperiod: amount of daylight in 24 hours. Changes seasonally and longitudinally. 12 hours always at equator. Seasonal cue in photoperiod. Animals can change behavior based on this as a cue. Birds use photoperiod to decide migration: migration- breeding- molt. Photosensitive- photostimulated- photorefractory. photorefractory cycle starts at hatching with long daylight. They are not responsive to photoperiod of long days. (reproductively) photosensitive is state in which bird is sensitive to stimulatory effects of long day. Usually starts in winter, though, before it would need to be stimulated. Photostimulated state when bird is actually experiencing long photoperiods and secretes hormones for reproduction. In order to transition from photorefractory to photosensitive it has to experience several weeks of short day photoperiods.

first primates

plesiadupiforms (first primate like mammal in early paleocene until end eocene). Generalized arboreal primates, different lineages had teeth indicating different diets (frugivorous, gum-eating, folivorous, insectivorous) Shared derived tooth and skull features with euprimates, but had smaller brains and longer snouts. Lacked postorbital bar and large incisors making them appear rodent like. All retained claws, none specialized leapers. Fleshy fingers better for locomotor behaviors on the small-diameter supports, first appearance increases manual dexterity. First record of these found in stem primate curpolests simposi. Prosimians first true primates (euprimates, early eocene). Include lemur like adapoids (3 families) and tarsier like onomyoids (2 families). Larger than plesiadapiforms, larger brains, forward facing orbits, and longer hindlimbs for arboreal movement. Extant ones include lemurs. Fossil record support split between lorisiforms and lemuriforms 40 MA. Generally small, nocturnal, long snouted, and small brained compared to more derived anthlopoids. Promisianns are paraphyletic because of several derived features. Tarsiers are more closely related to anthropoids than other promisians. Molecular data supports this. Division of primates into strepsirrhinic (lemuriforms and lorisiforms) and haplrhini (tarsiers and anthropoids). Extant strepsirrhined form monophyletic grouping. Debate on if adapoids fit in that clade or are related to haplorhines. Darwinisplaced close to origin of anthropoids, thought to be "missing link", but is disputed. Think darwinis and adapoids should be linked to strepsirchine. Issue comes when adapoids are united to anthropoids. Tropical climate in cenzoic northern hemisphere reflected by diversification of early cenzoic primates. Early primates declined as climates cooled late eocene. Extant promisians first known from late-middle eocene. Lemurs in isolation from the rest of the world evolved their own version of primate diversity. Much of this diversity is now gone due to humans. Some giant lemurs could have been alive 500 years ago. Lemur decline continues and are threatened with extinction.

birds and dinosaurs (archaeopteryx)

posture is similar, long s-shaped necks, feet with 3 toes pointed back, weight bearing on feet, ankle joints between tarsals, presence of holuoneumatic bones. Lateral glenoid fossa (where humerus articulates with pectoral girdle). Dromeosaurs widely thought to have feathers. Birds are thought to be last ancestor (living theropod dinosaurs) of dinosaur. Feduccia thinks they branch dinosaurs before teh archosaurs. Compared digits of birds hands in embryonic development with hands of dinosaurs during development. Ostrich has 5 fingers in development, but only have 3 fingers. 1 and 5 are vestigial. Theropod and basa ornithischial and sauropodomorph and anthropod hands: 3 principle digits, but the digits shown are not the same, in theropod 1-3 developed and 4 and 5 are vestigial- independent events.

aquatic mammals

predatory aquatic mammals use a variety of feeding mechanisms (biting, suction, filter). Locomotion may be via limbs (paraxial) or undulations (axial), most semiaquatic use limbs, but it is inefficient in terms of drag. Full aquatic use axial with dorsoventral flexion instead of lateral like fish. Axial swimming modification of flexion of vertebral column used by terrestrial mammals. Fully aquatic have elongated backbones by similar hox gene expression. Early cetaceans and sirenians had hindlegs, but were lost for axial swimming. Pinnipeds retain hindlegs and zygopophyses in trunk vertebrae (tail is modified hindlegs turned back). Sea lions and walrus can urn hindlegs and move on land with vertical flexions of vertebral column. Sea lions have paraxial swimming (forelimbs synchronic movement for underwater flying). Create lift with dorsoventral movement of hindlegs.

Bird feeding

predatory mechanisms of birds concentrated in beak and feet. Beak, tongue, and intestine modifications associated with diet. Birds use beaks to feed, groom, manipulate objects, social interactions, and thermoregulation. Generalists have beaks that can seize and process animals and plants. probers and gleaners (extract food from small spaces) have pointed beaks to use like forecepts. Carnivorous birds use heavy beaks as bludgeons to kill prey. Hawks and owls kill prey with talons and tear pieces with beak. Falcons stun prey with dive impact and bite neck. Fish-eating birds can filter prey from water. Seed-eating birds can slice into seeds with lower jaw or crack husk with upward pressure of lower jaw and then use tongue to remove contents. Woodpeckers wedge nut into a hole in bark and hammer it with bill. Skull of most birds have 4 bony units that move in relation to each other. Upper jaw flexes upward and lower jaw expands laterally. This kinesis increases birds gape and assists in swallowing large items. Long-billed shore birds probe mud and have distal rhynchokinesis in which flexible zone of upper jaw moved toward beak tip. Tip of jaw lifted without opening mouth. Tongues important to find food. Hyoid bones that support the tongue are elongated and housed in sheath muscles that passes outside skull and rests in nasal cavity when they contract, hyoid bones pushed around back of skull and tongue projects. Nectar eaters have hair-thin projections on tongue for nectar to adhere to.

Saurischian

saurischian in 2 lineages: herbivorous saurpods and carniverous theropods. Derived sauropods were quadropedal, but had bipedal ancestors. Basal sauropodmorphs were most divers late triassic- early jurassic. prosauropods had long necks, small heads, suggesting eating of plant material off of ground (reach tall plants.) Derived sauropods (neosauropods) were enormous. Gigantism evolved independently in several lineages (ability to grow big is ancestral). Largest terrestrial vertebrates. Length of neck from lengthening of cervical vertebrae and increasing their number. Neosauropods had small heads in proportion to body, large head could have been too much leverage. Macronarians had deep snouts, big nasal openings, spaculate teeth (which replaced often). Diplodocoids had long flat snouts, nasal openings at front of snout, peg like teeth at jaw front, teeth replaced ever 35 days, forelimbs shorter than hind. Simple teeth in neosauropods as bulk feeders. enormous quantities digested slowly. Teeth striped branches, but little oral processing. Large intestinal tract allowed for slow passage and time to ferment food. Sauropods were heavy and forces favored strength with light weight. Axial skeleton, vertebrae, and ribs are pneumatized. Moving progressively back until hips and tail vertebrae. Neural spines held massive elastic ligament thet supported head/neck/tail. Trunk deep like elephant. Legs held under body only 1 foot apart as shown by fossil trackways. Limbs held straight and moved fore/aft parallel to midline. Elephant like gait. Sauropods lacked frills and sexually dimorphic displays. Evidence of sociality is sparse. less extensive that ornithischians. Analysis of 2 isotope ratios in camarasaurus bones suggests they made seasonal migrations. Don't know if individual or as groups. Series of tracks found is evidence of possible herd behaviors. Other evidence of multiple individuals in the same age range: juveniles stay together. Often seen in grazing mammals (several sites like this found). Concentrations of nests and eggs found suggests they had nesting grounds every year. Eggs found with fossilized vegetation, each female deposited about 50 eggs. Eggs had large volume. Some nesting sites had large egg quantities. No evidence of parental care. One nest has embryos that probably needed an adults help. Sauropods had very long necks, possibly useful to reach trees, but unlikely through mathematical analysis: issues to keep blood pressure high enough to keep head up for so long. Possibly for horizontal sweeping arch on ground. Theropod lineage of saurischians were carnivorous. Basal ones were small with long arms and legs. 3 fingers on hands, palms inward. Hands used to catch and hold prey. Derived lineages are large and attack with jaws, fast moving and catch with forelimbs, or fast moving. All theropods were fleet footed. (tyrannosaroides, ornithomimisauria, maniraptora, deinonychosaurs) tyrannosaroides: early ones were small derived ones were very big. Distinctive features appeared in early s mall ones. 3 stages of life history (1. skull was strengthenedm anterior teeth serrated, jaw muscles more powerful; 2. large skull, tiny forelimbs, long hndlimbs (raptorex kiegsteini); 3. tyrannosaurs increased size). Tiny arms and robust caws had function, but it's unknown. Teeth large with powerful jaw muscles, fossils found with deep tooth marks and fossilized feces (coprolites) of tyrannosaurus has bone fragments, teeth distribution allowed for enormous bite force in localized areas. Feathers may have been ancestral character, protofeathers found in many theropods. Occurred in only some tyrannosauroides. Ornithomimisauria: lightly built, cursorial coelurosaurs of cretaceous. Not closely related to birds, but had bird like forms (ostrich like), long legs with 3 toes, femur 2X tibia length. small skull on long neck, toothless jaw and horny bill, long forelimbs with 3 digits, flexible wrist for capturing prey. Probably omnivorous. Possibly lived in group in open regions (long legs) maniraptora: active predators, long legs and arms, grasping fingers, covered in feathers. Oviraptosaurids group of small maniraptorans late cretaceous. Omnivorous/herbivorous with horny beaks, boxlike skulls, and sexually dimorphic head crests. Derived meniraptorans had claw on second digit of hindfoot, consummate predators with large eyes and brains. Claw was held off ground in locomotion. deinonychosaurs had a sickle shaped claw not used to slash, but perhaps to hunt in groups. Claw may have been used to pin prey while tearing apart if solitary hunters. Large theropods may have been individual hunters, smaller species may have been more social. Multiple juvenile fossils found together. Parental care seen through fossils of theropods that dies while caring for a nest. Embryo in egg was for theropods. Fossils of adults sitting on eggs. Male parental care ancestral for coelurosaurs and retained in most primitive extant birds. Likely that male maniraptorans were caregivers.

Semiaquatic mammals

semiaquatic mammals have more paddle like limbs and denser coats. Lineages of semiaquatic mammals evolved several times. Monotremes (platypus), marsupials (water opossum), placental order Eulipotyphla (water shrews) and atrosoricida (odder shrew) and rodentia (beavers), and carnivora (otters) and artiodactyla (hippopotamus). Fully aquatic mammals only evolved 3 times: sirenia (dugong and manatees), cetacea (whales and dolphins), cernivor (pinnipeds and seals). Pinnipeds are only group that come on land (mate and give birth. All fully aquatic mammals use blubber instead of hair for insulation.

birg song and endotherym

song in the cold in "hot": memory of and preference for sexual signals perceived under thermal challenge. Lincoln sparrows: breed in cold regions at high latitudes in summer. Temp drops 6 degrees in night. At this time, males sing the most (when it's coldest around dawn). Female birds in labs and played different males songs. Day 1,2,3- animals in temp (chamber could control temp). Day 4 , bird moved to a different chamber with 2 speakers, choose between 1 of 2 songs. Song 1 played at dawn 30 minutes on day 2 (female 1: 15 degrees, female 2: 1 degree). Song 2 played at dawn 30 min on day 3 (female 1: 1 degree, female 2: 15 degrees). Then put in second chamber with song 1 and 2 and allowed to choose at dawn. Repeated for 7 pairs of females. Female spent more time near speaker when song was playing in cold. When in the second chamber (warm temp), spent more time near speaker of song that they heard while it was cold. Memory for song and cold preference. Moles possibly advertise cold hardiness.

bird body size

substantial reduction in body size characterized the evolution of birds. Body size of proavians shrank from 25 Kg to 6.5 kg. Not a general feature of coelurosaurs because some lineages grew larger (tyrannosaurus, oviraptosaur)

Wing feathers

symmetrical pennaceous wing feathers adequate for balancing, gliding, and leading, but power flight requires asymmetrcal primaries to provide thrust. Symmetrical feathers wide spread among coelurosaurs, but asymmetrical only from archaepteryx and more derived farms. Avialae had asymmetrical wing feathers, but shoulder joint prevented wings from being lifted above the back in all forms earlier than onithorales. Two conflicting ideas about when powered flight evolved.

ornithischians (mesozoic)

1500-2000 species of dinosaurs estimated during mesozoic. Dinosauria considered to be monophyletic lineage containing 2 sister lineages (ornithischia and saurischia). All ornithischians were herbivores (hadrosaurs (duck billed), stegosaurs, ceraptopsians (horned)) greatest diversity in late cretaceous. Saurischian had sauropoda (long-necked and tailed herbivores, max diversity in jurassic) and theropoda (carnivores with diversity in late cretaceous.) Some ornithischians had elaborate crests and decorations, probably lived in groups. All were herbivores feeding on low vegetation. All had horny beaks and processed food orally. (chewing). 3 major lineages: thyreophora (armored), marginocephalia (horned), and ornithopoda (duck billed) thyreophora: armored dinosaurs with rows of osteoderms from neck to tail. 2 major lineages (stegosauria and ankylosauria) were quadropedal. Stegosauria: most abundant late jurassic, small heads and short/sturdy forelegs and long hindlegs. Kept head close to ground. Horny beak at jaw end used stone gastroliths in a muscular gizzard to pulverize plant material. Ate a lo without chewing. Had double row of spines along spine. (hypertrophied keels of ostoderms). Plates initially thought to be for protection, but issues is that they still left large areas unprotected. Possible role as heat exchanger, grooves on surface for blood vessels and large surface area, but reanalysis showed that the channels carried nutrients to the sheath and had no role in thermal regulation. The vessels were too small in the plates to be involved in thermoregulation. Combination of plates and spines were species specific and dimorphic. May have increased size and deterred predators. Tails with large spines at tips for defense (tail whip) ankylosauria: heavily armored in jurassic and cretaceous. quadropedal arnithischians. Shorth legs and broad bodies with osteoderms fused on neck, back, hips, tail to produce shields. Bony plates covered skull, jaws, eyelids. Some had bone on tail end like a club. Marhinocephalians: name from bony shelf at rear or skull, 2 lineages. ceratopsia: The horned dinosaurs, most diverse margincephalians, appeared late jurassic/early cretaceous. Frill over neck by enlargement of parietal and squamosal bones, parrot like beak, teeth arranged in batteries with knfe like edges, probably sheared vegetation. Derived from a bipedal ancestor, early ones (protoceratops) were small with frill and lacked nasal horns. Triceratops: short frilled extended over neck. Titanoceratops: long frill extended 1/2 trunk length. pachycephaosauria: small/medium bipedal dinosaurs in cretaceous. Have pronounced thickening of the skull roof and array of bony projections on skull in some species. Ornithopoda: middle jurasic- cretaceous. Large quadropedal, small bipedal. hadrosauridae: last group of ornithopods to evolve (midcretaceous) and most speciose lineage. Very large, anterior jaw toothless in horny beak, battery of teeth in rear with 4 tooth rows containing 40 teeth, several sets of replacement teeth behind. Most advanced vertebrae chewing apparatus.

cetaceans

Believed that cetaceans evolved from terrestrial mammals. Could be from aritodactyls (even toed ungulates) based on obscure nantomical details, but this is found unlikely. However- molecular data showed a very close relationship between the 2, they should even be in the same order (form sister group with hippopotamuses) Cetaceans have large brain for body size, lack hair and ears, nasal opening on top of head. Some retain vestigial pelvis, but lost other hindlimb elements. Swallow food without chewing. Toothed whales have single set of teeth, lack incisors and canines and have multiple simple cheek teeth. 2 groups of modern cetaceans. small-medium sized toothed whales (sperm whale and dolphins) and large whales. Toothed whales eat large prey items and evolved echolocation to locate prey. Baleen whales lost teeth and evolved baleen (keratinous sheets hanging from upper jaw to strain water for food). Mysticetes have ability to hear low frequencies, also used for communication. Hearing evolved before baleen and large body in mysticetes. Idohyus closely related to ancestral lineage of cetaceans (small artiodactyl). Ear region like cetacean (thickened auditory bulla (involucrum) for underwater hearing), heavy bones indicate semiaquatic. Eocene fossil cetaceans belong to archaeocetic (largely extinct by end of epoch). Odontoceti and mysticeti formed neoceti group and srose from archaeocetes. earliest archaeocetes were pakicetidae (early eocene), primarily terrestrial with amphibious features. ankle joints like artiodactyls which confirms relationship of cetaceans an dungulates. Pakicetids had teeth like fish eaters, orbits on top of head to observe while floating. Postcranial remains show heavy bones for ballast and tail like otters. O2 isotope ratios in teeth showed they drank freshwater, amphibious life in rivers. Middle ears slightly modified for underwater hearing (diagnostic cetacean features of ear region) Abulocetidae (early-middles eocene). Hindlimbs with enormous feet possibly for dosoflexion locomotion with paddling while hindfeet point back. Fingers not embedded/webbed into flipper. Fingers and toes had little hooves. Fossils in coastal environments. Still drank fresh water. Robust skulls and teeth suggest crocodile like ambush predators. Ambulocetids specialized branch, not involved in cetacean history. Rmeintonocetidae (more derived group, also specialized side branch). Hindlimbs connected to vertebral column, capable of bearing weight on land. Delicate skull with narrow snout and small eyes, indicating fish diet. Ear anatomy suggest improved underwater hearing (enlarged lower jaw canal that housed sound-conducting fat pad, reduction in size of semicircular conals associated with underwater navigation). Tooth isotopes show they did not drink fresh water, obtained water from food like modern cetaceans. protocidae more like cetaceans. More reduced hindlimbs, retained connection to vertebral column. retained pelvic girdle, but lost connection between ilium and pelvis and sacrum in vertebral column. Evidence shows for land birth, embryo born head first. Early ones probably relied on hindlimb paddling and went to axial locomotion of lumbar later. Lifestyle like modern seals, fully aquatic but not obligatory. Inner ears show intermediate function between terrestrial and cetaceans (air and underwater). Specialized underwater hearing evolved in 2 different groups. Basilosauridae (late eocene) obligating aquatic. Lost hindlimb connection to vetebra and greatly reduced hindlimbs, may have been used for copulation. Pelvis remains for genitalia muscles. Short necks and flipper like forelimbs with immobile elbow. Tail vertebrae suggest tail fluke like cetaceans. Ears like cetaceans (bony ear isolated from skull by air-filled sinuses), but retained external auditory meatus, in north They had elongated trunk and small heads, originally mistaken as sea serpents. Initial neoceti radiation coincided with extinction of archaeocetes at eocene-oligocene boundary, happened at craetion of Antarctic cirumpolar current. Modern cetaceans have "telescoped" skull, nostrils moved to top of head and jaws were elongated. mode of this different in mysticetes and odontocetes, indicating independent evolution. Earliest baleen whales were small and retained teeth. May have lost teeth in association with suction feeding before acquiring baleen. Evidence of echolocation in earliest toothed whales adapted for catching large prey. Skull have convergence with crocodiles. Modern cetacean evolution probably related to changes in oceanic circulation that increased productivity, resulting in novel feeding strategies like echolocation. Cetacean radiation also happened late miocene with lowering of high latitude temp and changes in oceanic circulation (many families went extinct). Giant baleen whales appeared inpliocene withs easonal ocean upwelling. NA baleen whales were 20X more abundant before human commercial explotation.

Endotherms in desert

In a hot desert, endotherms are in a temp gradient where they are cooler than environment. They continuously absorb heat and metabolic heat needs to be dissipated. Temp stress and H2O scarcity challenge endotherms in deserts. Evaporative cooling is effective when water is unlimited. Most mammals die after losing 10-20% of water. Disposing of waste in desert is another problem because it makes them lose a lot of water (50-70% of content). Birds can at least reabsorb water. Thick medullary kidneys in mammals allows for highly concentrated urine. Methods to cope with desert: avoidance- avoid conditions with behavior rarely exposed to desert relaxation of homeostasis- survive by tolerating hypothermia, hyperthermia, dehydration. Avoidance: deserts are hot in the day and cold at night, shelters constructed by animals allow them to escape the extremes, One animals burrow can provide shelter for many others species. Heat can also be escaped by moving higher off the ground. Relative humidity is higher in burrows and bids can easily find oasis. Rodents: normally nocturnal and live in burrows, allowing for life in desert. Have kidneys that produce concentrated urine (2X that of human). Kangaroo rats most specialized: spend day in burrows and emerge at night to forage. birds: flight provides more mobility and can fly many km to find water. Normally high body temp of birds gives another advantage. Problem with temps being too high is experienced for a shorter period of time, birds can also tolerate moderate hypothermia, (same in all birds). Desert birds have to supply flightless young with water. Some fledglings receive H2O from food. reproduction usually occurs when succulent food is available. In australia, sight of rain stimulates courtship in some birds. Columbiform birds (pigeons) feed babies a liquid substance similar to mammalian milk (primarily H2O and protein and fat)- places water stress on adult. Seed-eating bird babies find seed within hours of hatching, but need H2O. Adult males will transport water in breast feathers. Relaxation of homeostasis by hypothermia: temporarily allowing body temp to rise above normal set point to conserve water. Small mammals: squirrels are active in midmorning and early evening. Squirrels use variability of body temp during day to store heat during activity. high temp limit to short bouts of activity, because small animals heat quickly sprint between patches of shade and cool rapidly, so run across open area then seek shade. Large mammals: absorb heat slowly from environment and have longer strides to go further in a given amount of time, but are too big to burrow . Also, high fat content/insulation allows absorption of large amounts of heat energy before body temp gets too high. Distribution of hair on camels aid in reducing heat load (shorter hair on belly, so lay down on night cooled surfaces in morning). Also squish side by side to reduce environmental heat contact. Hair protects top of body. Watered camels temp goes form 36-39 degrees, dehydrated camels temp goes from 34.5-44.5 degrees. Camels conserve water by tolerating hyperthermia during day. Hypothermia also reduces energy flow from air to camels body, allowing for les heat exchange and saved more water by eliminating temp gradient. Squirrel heats and cools many times in a day. Camel heats in a day, cools at night. Camels maintain lower head temp to protect brain through countercurrent heat exchange to cool blood before t reaches brain. Blood in cavernous sinus before it reaches brain. Blood returning from cooled nasal passage, which cools arterial blood before it reaches brain. Many ungulates have a carotid petia mirabile with cavernous sinus, but horses cool blood in the internal carotid arteries by passing it through guttural pouches (outgrows from auditory tubes that envelop internal carotid arteries and filled with air cooler than blood.) Many desert rodents can reduce body temp in response to food shortage. Duration of this hypothermia is proportional to food deprivation severity, as food is reduced it spends more time in hypothermia. General phenomenon among seed-eating rodents, assess rate at which they accumulate food supplies. If a species that stores food has food on hand, but couldn't find ne food, it will enter hypothermia. Probably a result of chronic food shortage that desert rodents face. (variations of rainfall patterns and low primary productivity in deserts). Camels will press against each other when they are too hot. Reduces effect of surface area, minimizes rate heat radiates into them.

mammal reproduction

In marsupials, vas deferentia of males don't loop around ureters and oviducts in females don't fuse in middle line because of location of ureters. Lateral vaginas for passage of sperm. Young born through midline structure, pseudovaginal canal which develops the first time a female gives birth. Monotreme male testes retained within abdomen. Testes of therian descend into a scrotum outside body. Hypothesis for this is that it provides a cooler environment for sperm production, or avoids intra abdominal pressure that would be exerted during bounding gait. Scrotum anterior to penis in marsupials and behind penis in most placentals. Scrotum evolved independently in the 2 groups of therians due to difference in location and physiological control of testicular descent. Monotremes and marsupials have bifid (forked) glans penis, placentals have a single glans. Some male placentals have a bone in the penis (os penis/baculum). Extend penis from sheath during urination and copulation. Citoris of female homologue to penis. Females may have bone here (os clitoridis/ baubellum). Ovaries of monotremes are larger than therians, and provide embryo with yolk. In all mammals, eggs fertilized in anterior portion of oviduct (fallopian tube) and enter uterus. eggshell is parchment like. Receives nutrition from uterus before secreted. Monotremes lay 1-2 eggs and young hatch soon after. Platypus lay eggs in burrow, echidnas keep eggs in ventral pouch. Young hatch altricial and brood off mother. Viviparity is used in therians. Variation in types of placentation, Choriovitteline placenta: from apposition of yolk to chorion, first placental structure to appear after implantation. Chorioallatoic placenta from fusion of allantois to chorion typical of placentals. Allantois never reaches chorion in marsupials. Choriovitteline placenta in placentals is usually transitory. Chorioallantoic placenta variations. Hemochorial placentals (ancestral), maternal blood in direct contact with fetal tissue. Endotheriochorial placentals, chorionic tissue of fetus penetrate endometrium of uterus until maternal blood vessels. epitheliochorial placentals, chorion in contact with surface of endometrium. Growth of chorioallantoic membrane in marsupials is slow. Thought that out growth of this placental membrane is suppressed in marsupials. Have ranscient shell membrane and placentation doesn't occur until shell degenerates. Marsupial neonates are guided by shell and use front claws as holdfasts for crawling. Neonates retain interclavicle and complete coracoid bones of monotremes. This limits subsequent development of adult shoulder girdle. Kangaroos lick a path for neonates from urogenital sinus to anterior pouch. Content of milk from the 2 nipples depend on how long baby has been suckling. females can have 3 young at different developmental stages when food is plentiful. Presence of suckling stimulates protracting, which inhibits corpus lateum, holding fertilized egg in oviducts in embryonic dipause (arrested development), embryo starts to develop when neonate reduces suckling rate. Embryonic dipause also occurs in some placentals, enables mom to space successive births and separates time of fertilization from start of gestation. basal therian condition probably had birth of altricial young. Possible that viviparity evolved independently in marsupials and placentals. Early therians probably had short gestation with several litters in rapid succession and short life spans. Increased expression of cyclin (immunosuppression) may have aided in evolution of fusion of fetal and maternal cells in placental formation and maternal tolerance of fetus. May be responsible for long term gestation. May be implicated in initial evolution of viviparity. Features of therians related to viviparity: X/Y sex determination, genetic imprinting, X-chromosome inactivation. Marsupials thought inferior to placentals because of low diversity, and only being in australia. Marsupials actually have less diversity because they had less land area to inhabit and radiate on. Marsupials and placentals evolved different, but equivalent reproductive strategies. Marsupial reproduction system may have placed some limitation on marsupial diversity. Fully aquatic marsupial couldn't carry altricial young in pouch or give birth under water. Only semiaquatic marsupials exist. Nor marsupial group equivalent to bats. Flight evolved only once in synapsids. No hoofed ungulates among marsupials, probably because marsupials can't reduce fore feet to nongrasping limbs. Need to climb to pouch. Marsupial skulls show less variability than placentals, probably related to early ossification of bones around mouth for nipple fastening, constraining skull.

Primate social systems

Most research done on complex social systems of primates. Over 200 species in very diverse habitats. Many are generalist. Social systems classified by male and female movement: Female transfer system: most females move from group they were born in. Females in a group are not closely related, but males are. These tend to be small groups that males defend. Male transfer system: females stay in birth group and males don't. Social relationships between females based on kinship. Group size usually larger than female transfer system. monogamous species: single male and female form pair, show little sexual dimorphism, share parental care and territory defense. Offspring expelled. Solitary species: live single or with offspring, males sometimes have territories. 3 ecological factors shape primate social systems: food distribution: defensibility of food determines if individual will defend a territory. group size: distribution of food may determine group size (larger groups become smaller when food is scarce) predation: predation risk determines if individuals travel alone or with group. Life in primate group balances competition and cooperation. Competition manifested by aggression (food defense, mates, sleeping site). Can establish dominance hierarchy.) 4 types of relationships among individuals: Adult-juveniles associations: juveniles depend on adults for a long period. Some mothers are protective, some are permissive (wean off earlier). Offspring of permissive mother have higher mortality. Older siblings may help or assault infant. Allomaternal females will provide care to unrelated offspring. (prefer younger infants, sibling may participate more, more care for infant of high ranking mother). New world males participate in extensive care, new world males just have more friendly contact. female kinship bonds: females of some species live in groups. Females form a hierarchy. Related females in a group called matrilineages. Support female relatives against those unrelated. high ranking females maintain position. Social rank of matrilineage not fixed. Female kinship important in male transfer systems, fitness of this unknown. male-male alliances: male rank in male transfer systems depends on individual attributes and are less stable. New young males have greatest fighting ability and higher rank. Alliances may allow older male to win. Cooperative male relationship more common in female transfer system, males have kinship. Males cooperate within a group. Male-female friendships: a female could have 1 or 2 friends, which spend more time together and stay together for years. Friendship will protect a female and offspring, perhaps gives male a chance to mate later on. Proportion of infant survival higher for females engaged in social behavior. Women with extensive social networks give birth to bigger babies with lower disease incidents. Feeling lonely correlated with higher death rates. Support systems provide endorphins. with familiar individuals around, lower heart rate and cortisol levels, which lengthens life span. Social interactions may provide protection from harassments and access to resources. Observation suggests primates recognize different kinds of individual relationships. Babies give different screams based on rank of attacker and mothers act accordingly. Mother may respond more to screams of own baby. Others respond by looking at mother. Observations of redirected aggression suggest primates classify other members of a group.by matrilineage an friendships. Victim will attack friend of individual that attacked them. Suggest that primates can recognize detailed social relationships.

Bird senses

Vision of birds provide info. on rapidly renewed basis about position and presence of obstacles in path. System active even while sleeping. Large optic lobes and cerebellum. cerebrum less developed than mammals, dominated by corpus striatum. Eyes are very large, brain displaced dorsally. Same basic structure, but varied shape. result of putting large eyes in small skulls. Visual acuity of birds of prey is similar to humans, but can see fast. Have a high flicker-fusion frequency. May be impotrtant to capture flying insects or while flying. Pecten structure in avian eye formed by blood capillaries surrounded by pigmented tissue and covered by a membrane. Arises from retina where nerve fibers join at optic nerve. Function of it is unknown, can be large or small. Could reduce glare, reflect objects above bird, produce stroboscopic effect, visual reference point, but none are plausible. Large blood supply suggests that it could provide nutrition to retinal cells and remove waste. Birds have 4 photosensitive pigments (wavelengths: red, green, blue, deep blue/UV). UV reflectance distinguishes from females, indicates physiological status of prospective mates, demonstrates health. Could help parents distinguish own eggs or enhance effectiveness of warning colors. Oil droplets found in cone cells. range in color and act as filters. Function unclear. Birds that see through water have mostly red. Aerial hawks have yellow. Columellal transmit vibrations of tympanum to oval window of inner ear. Cochlea specialized for fine distinctions of frequency and temporal pattern. Has cox more hair cells per unit length than mammals. Folded glandular tissue above busilar membrane may dampen sound allowing rapid response to sound change. Sound sensitivity similar to humans. Have large tympanum relative to brain. Owls have highest ratio of tympanum area to oval window (meaning higher sensitivity). Owls have large cochlea and developed audio centers in brain. facial fluff acts as a sound reflector to focus specific frequencies and amplify asymmetrical skulls assist with localization of sounds in different axes. Integrate time and intensity to form a map. Olfaction important for homing in pigeons. Tubnosed sea birds use it during migration to locate food areas. Although, it can lead sea birds to eat plastic (bacteria on plastic release scent). Vultures locate carcasses with smell. Odors also influence social behavior- role in species/sex recognition, choice of partners and care of eggs. Odors originate in uropygial gland secretions. Waxy fluid spread on wing during preening. Olfactory bulbs in birds vary in size (25% brain-5%) species in aquatic habitats have larger bulbs. Small bulbs don't correspond to sensitivity. Olfactory receptor genes code for proteins that detect odors. can be grouped in gene families. OR genes in a family responds to similar chemicals. In birds, expansions of certain OR genes are associated with ecological characteristics. Aquatic bird have families that respond to to hydrophilic compounds. Owl skull adapted for excellent sound location. Separation of left and right ears on that plane. asymmetric ears: one ear is higher than the other; allowing localization in up and down plane. One ear is set back further than the other to allow determination of distance.

testosterone in egg yolks

huber schwbl found that testosterone is in egg yolks. Testosterone in ovary goes into brood and ends up in yolk. Occurs before sex determination. Testosterone concentration highest in yolks of last laid eggs: possibly gives them an advantage.

Endotherms in winter

in winter its a challenge, more food needed to keep warm, but less food is available. Animals < 100g are more vulnerable because of large SA:V ratios (high loss of heat), large food requirement because mass-specific metabolic rates are higher than those of larger species, thinner layers of insulation. Sheltered microclimates decrease heat gradient between animal and environment. Facultative hypothermia (intentionally lowering body temp.) also decreases heat gradient. Daily cycles of body temp. are universal and bogy temp. varies with physiological status (pregnancy). Seasonal reductions in temp. (seasonal hypothermia) show species with lower body temps in winter. They allow body temp to drop and become inactive (hibernation: high drop in temp for weeks to months) seasonal hypothermia: dropping body temp in winter wile maintaining normal activity. Rest-phase hypothermia: decrease in body temp that coincides with an animals normal period of inactivity (like at night). Insulation and thermogenesis balance heat loss at this level and saves energy due to lower heat gradient. Increase in metabolic rate at end of period increases body temp. Metabolic rate rises briefly over resting for initial warming. Energy used for that is small compared to energy saved. Chickadees use rest-phase hypothermia, in north during winter. 30% reduction of energy used when cooling at night. Rely primarily on fat stored from day feeding to supply needed energy at night. Usually 0.8 g when increasing activity in evening and fat stores decrease to 0.24 g. Fat metabolized overnight corresponds to metabolic rate expected for bird with body temp 30 degrees. If bird maintained a 40 degree temp at night, it would require 0.92 g of fat, so they would starve before morning without rest-phase hypothermia. rest-phase hypothermia allows to speed the rebuilding of energy stores during migratory stopovers. Can save more that 30% with lower body temp. hibernation: deep hypothermia, nearly confined to mammals. Motor response reduced, but some sensory perception of auditory, tactile, and environmental temp retained. (can arouse using heat production by brown fat). Deep hypothermia not as advantageous for large animals. Energy cost for maintaining high temp is lower in large animals, so small ones gain more from hypothermia. Large animals also cool slowly, so metabolic rate doesn't decrease rapidly. Large animals also have more tissue to rewarm on arousal with a higher cost. During hibernation: body temp drops within 1 degree of surroundings, active metabolic suppression starts before body temp falls and reduces oxidative metabolism to 1/2 O, regulation of body to new hypothermic temp, respiration is slow, heart rate is reduced, blood flow to peripheral tissues shut down along with blood flow posterior to diaphragm, blood retained in body core. Arousal: heat production in brown fat and shoulder distributed with circulatory system. (first: head, heart, anterior body). Periodic arousals in hibernation are normal: large portion of energy used in hibernation. Male ground squirrels leave hibernation early to get territories and reenter early june (juveniles are active till september to build fat storages.). Cost of arousal: warming, sustaining warm temp, metabolism as body temp decreases to hibernation again. (these 3 = 85% of total energy). Unknown why ground squirrels undergo these arousals, don't store food in burrow to eat, but do urinate during arousal. May also allow squirrel to determine suitable environment for energy. Communal hibernation: many ground squirrels hibernate in groups. Heap together to reduce SA:V ratio and reduce heat loss. Bouts of arousal in communal hibernation marmots are synchronized and saves energy because heat is shared by all individuals. Weight loss in highly synchronized groups is 20-25%, but is 40-45% in poorly synchronized.

mesozoic birds

2 independent bird radiations enantiornithes: articulation between scapula and coracoid is reverse of that in extants, dominant in cretaceous. Most small/medium and probably lived in trees. Some had long legs (wading birds) others had powerful claws like extant hawks. Ornitharae: later cretaceous and became variety of ecological types. Early ones were small, but in late cretaceous it had waders, perchers, and secondary flightless swimmers and divers. Neornithes probably originated from ornitharines late cretaceous. Most common ancestor may have been seen eater (neornithes) Molecular evidence place second radiation within cretacoeus. Vegastaai is a member that includes extant ducks and geese. Diversification of modern birds began before cenzoic. Fossils of gallipaceaus (fowl) and palaognathaths (flightless) are found in cretaceous deposits showing some modern bird radiation during mesozoic. Fossil record too sparse to say if bang of neornithine radiation occurred before or after end of cretaceous.

syrinx of song birds

2 parts, left and right independently controlled. Key element to produce song. Song is of learned vocalization in a specific group of song birds. Learns species specific song from others while young. Only 6 groups of vocal learners (6 taxa)- no auditory learning. Song birds don't produce song when raised in isolation. Although, other vocalizations are not learned. Other taxa with vocal learning: humming birds, parrots, bats, sedations, humans. Suggested that it evolved 6 times.

radiations that preceded dinosaurs

2 radiations preceded them. middle permian- middle triassic: synapsids most abundant on land. Cynodonts carnivores. dicynodonts and traversodontids herbivores. Most lineages extinct by late triassic. rhynchosaurs were small herbivores in early traissic. Basal pseudosuchians became predators ad herbivores in middle triassic. Herbivore lineages diversified late triassic. Herbivorous sauropodomorph dinosaurs expanded replacing earlier herbivores. Carnivorous lineage didn't diversify until after end triassic mas extinction of phytosaurs, ornithosuchids, and rauisuchians. Basal ornithodires radiated in triassic (almost dinosaurs)

factors in determining food availability

3 factors important in determining food availability: diet, dispersal of food, how food is gathered. Herbivore home ranges are smaller than carnivores. This reflects abundance of different kinds of foods. Grasses and leaves more ubiquitous, small home range provides all food needed. Plant materials of omnivores less abundant than leaves and grasses, and are mire fragmented in space because of different fruit seasons. Vertebrate prey for carnivores less abundant, so a larger home range is needed for adequate food supply. Home ranges are smaller if patches of food are more abundant and less widely dispersed. Home range of foxes dependent on shore line. Foxes on shoreline that has the current and are more productive in producing food will have a smaller home range. Individuals of a species probably encounter each other more frequently when home ranges are smaller, thus resource distribution can limit the degree to which social groupings occur. Sociality may influence resource distribution if groups can exploit resources not available to the individual. Influence of sociality on resource distribution seen in predatory animals that can hunt in groups. Hyenas in packs can hunt adult wildebeest when an individual can't. Some prey species have defenses more effective against an individual predator. Largely social predators attack larger prey than weakly social predators. Major disadvantage to group hunting is having more individuals to feed, so food requirement is sum of each individual. For group hunting advantage, per capita amount of food obtained must exceed amount caught by solitary hunter. Study of female lions show that the group hunters must hunt large prey due to being in a group. The advantage of being in a group provides better territorial defense. Their group hunting doesn't increase food capita compared too individual. Group hunting was a by product.

distribution of resources

distribution of resources is major factor in social structure, sociality won't happen inn resources in an area are too limited for more than one animals. home range in which an animal spends most of their time to find food and shelter. Not defended. Territories are defended. Having a home range gives value of familiarity. Many species employ traplining foraging in which they go over a regular route and visit certain places to find food. This demonstrates home range familiarity, with the resources likely available in certain places. Resource dispersion hypothesis: predicts that size of home range and individual animal depends on the animal's resource needs and distribution of resources. Species that need large food quantities need a larger home range. Home ranges should also be smaller in a resource rich environment. This hypothesis applies to any kind of animal and resource (food, shelter, mate access).

Cenzoic monotreme radiation

Canzoic radiation of mammals occurred during separation of continental masses. Vicariance is separation of stocks by earth's physical processes and not it's movements. Isolation of monotremes in Australia resulted from this. Dispersal reflects movement of actual animals, usually by spread of populations rather than long-distance movements of an individual. Best to explain distribution of most modern mammals. Duplication of mammals specialized for certain lifestyles resulted by separated evolution of different groups.

hominins and extinctions

Current status of primates is a microcosm of the plight of all vertebrates. 4 of 7 species of great apes are critically endangered. Illegal hunting is greatest threat to many primates, lead to significant losses in all populations. Weapons allow humans to kill largest and fittest adult, unlike most predators that kill young or elderly. Kill adults 14X more frequently. Humans influence vertebrates by modifying the environment with fire and other methods. Agriculture accompanied with settled populations increased the pace and scoped of environmental change. Urbanization and accelerating climate change are most recent impacts. Presence of humans can affect predators. Rapid diversity increase from past 100 ma interrupted by periods of extinction. Pattern of long lived species changed around the time of human dominance. We are in midst of "6th extinction", progressing at an extremely fast rate. Extinctions begin soon after humans arrive. There were many megafaunal animals in Australia when humans first arrived. Humans reached northern australia 65 ka, occupied dry center 49 ka, moved tasmania 39 ka. Australian megafauna disappeared 9 ka after human arrival. Similar correspondences on other continents. Dates of human arrival and extinctions a lot closer together, Coincidence between human arrival and extinctions provide circumstantial evidence of human evolvement in megafaunals extinctions, but not proof of sole responsibility. Other factors could be climate change, vegetation change, rival of other alien species, new pathogens and parasites. Fossil sites provide evidence that humans killed huge numbers of large animals. Sites dated 40-15 ka contain remains of 166 mammoths per site. Moa populations in New zealand had been large for many years, but extinct within 100 years of human arrival, butchering sites have remains of many along with piles of uncooked portions. Eggshells of 200 kg flightless bird Genyornic newtoni were cooked in fires. Only thing in common of megafauna driven to extinction is large body size. Life history include late maturation, late first reproduction, single offspring in year long intervals, low population densities. Ultimately can't rebuild population quickly. Proposal that we are in epoch of quarternary. The anthropocene. Resulted from overwhelming human global impacts. Increasing CO2 levels from burning fossil fuels have initiated climate change, risen sea levels, acidified oceans. Extreme weather conditions more frequent and severe, extremes of drought and rainfall. Human worldwide impacts traced by thousands of years. Include megafaunal extinctions, phenotypic changes in species, effects of agriculture on current plant communities, reduction in genetic diversity of animal populations. People who study stratigraphic markers in geological deposit are not convinced we are in new epoch. Cement, plastic have both been proposed as stratigraphic markers of anthropocene (microplastics are present in sedimentary deposits). Anthropocene working group (geologists, archeologists, climate change and atmospheric scientists) are working on a proposal for international commission of stratigraphy and international union of geological sciences. with evolution of humans, many other vertebrates are being driven to extinction. Main cause: climate change and habitat destruction.

evolution of humans, a timeline

Earliest homo species in H. habilis (east africa). Some think it didn't have enough derived features to be included in homo, others say it's distinguished by large cranial volume. Also had smaller face, smaller jaw, and dentition with smaller cheek teeth and larger front teeth. Had small body and some specializations for climbing, associated with marks suggesting tool use. Many split h. habilis into 2 speceis: H. rudolfensis (larger brain) and H. habilis. Some say H. ruolfensis was actually a member of K. platyops due to large brain. Homo erectus appeared around 1.9 ma, large body, small teeth and jaws, no climbing specialization.. H. erectus originated in east africa and lived with Robus A. and H. habilis. First intercontinentally distributes hominin spread to asia. This movement once seen as a landmark, but many other animals went between africa and asia. H. ergaster (older/african form, erectus reserved for asian form), thought to be more closely related to hominins. Several unique characteristics of erectus and egaster. Substantially larger than early hominins with major increase in female size to reduce dimorphism, implying change to monogamous pair bonding. Body proportions like that of humans (short arms, long lower legs, narrow palavis, barrel shaped chest). Larger brains than homo species implying greater nutrition needed tahn earliest homnins (metabolically demanding). avid tool makers. First homnins with human like nose (broad and flat, downward facing nostrils), jaw projected beyond plane of upper face, large teeth, no chin, flat forehead, bony eyebrow ridges. Fist hominins to have delayed tooth eruption and small teeth for body, suggesting cooked food. Delayed tooth eruption suggests human like childhood and extended lifespan and passage of learned info. Dmanisi dated at 1.8 ma, earliest date for a homini in eurasis. Not clear if offshoot from H. erectus of H. habilis. Had small brain case and large jaw. Smaller stature and brain and prognathus face make many think they came from a less derived hominin than h. erectus. also supported by elbow and shoulder joints. Lower limbs long for running and distance travel. "island rule" when animals are isolated on an island, small become large and large become small. H. floresiensis is a small human inhabiting flores island. Believed to be derived from H. erectus (most widely accepted), some think from a more basal hominin. found with tools, contemporary of modern humans during middle late pleistocene. Had primitive canines and premolars and advanced molars. Human remains appear shortly after disappearance of H. floresiensis. Most recently described in the genus is H. hatedi. Analysis suggest they are grouped with others of homo clade. Human like foot with curved proximal phlanges. Hand with robust thumb and wrist morphology similar to humans. Longer fingers than australopithecus. Cranial volume similar to dmanisis. Diet of hard food, higher rates of dental chipping. Homo sapiens includes modern humans and neanderthals. H. sapiens now reserved to modern humans. Species closely related to humans referred to as archaic homo sapiens. Homoheidelbergensis oldest archaid H. sapien. Many primitive characteristics of H. erectus, large cranial volume like modern humans. H. antecessor show a mix of modern humans and neanderthals. Cannibalistic. initially suggested as side branch of early pleistocene radiations that gave rise to neanderthals and H. sapiens. DNA of homo neanderthalensis suggest not directly ancestral to H. sapiens, but diverged as 2 lineages of H. heidelbergensis. Features represent derived condition for hominins. Short and stocky, interpreted a adaptation for cold conditions of ice age. More affected by ice age than humans. (differences in resource exploitation). Larger brainstem than h. sapiens, larger occipital area, h. sapiens have larger temporal lobe. Result from birth, H. sapien brain starts globular, neanderthal starts elongated. Neanderthals stronger than H. sapiens. Heavy wear on teeth. Stone tool makers with organized society and sophisticated tools. Evidence of circular constructions of stalagmites (oldest human constructions). First humans to bury dead with ritual. Neanderthal diet consist of pine cones, poplar, moss, rhinos. Probably hunted with weapons requiring close contact. Many skeletons show evidence of serious injury. Could live until 50 years (humans reached that in middle ages) Neanderthals and H. erectus in asia disappeared around arrival of H. sapiens and H. sapien populations greatly increased. Source exploitation of modern humans gave them advantage over neanderthals, Humans changed food-gathering methods to keep diets stable unlike neanderthals. Another study suggests that differences in levels of material culture could drive neanderthals to extinction. Humans better adapted to new environment (long range tools) Denisovans: hominin remains found in denisova cave. Large molars and lack traits of neanderthals or humans. genetic analyses show that denisovans split from neanderthals 430 ka. Main evidence for being and independent lineage is molecular. Genetically distinct from neanderthals.

Australopithecus

Earliet hominins are australopiths from east africa inpliocene. No miocene taxon a true hominin, possible early hominins found in forests, debate over hominin status of orrorion tugenesis and scahelanthropus tchadensis. Orrorion combine intermediate femur between miocene apes and hominins with large canines and finger bones for climbing. Sahercanthropus known only from skull, ventral position of foramen magnum suggests balanced head. Had small human like canines and molars., massive brow ridges are apelike cranial features. More derived ardipithecus probably upright biped with a foramen magnum with downward opening. Small canines with less sexual dimorphism like modern humans, has pair-bonding mating system. skeleton has features of hominins and great apes, pelvis indicates bipedal capacity, long toes and divergent big toe suggest arboreal. Long arms and hands , no evidence of knuckle walking, wrist and finger joints suggest hands used to support while bipedally walking. Suggest bipedalism evolved in trees. Had smaller brain than australopiths, face sloped less than chimp and more than derived hominins, shows human and chimp common ancestor not like simple chimp. 2 generalzed types of australopiths: gracile (slender) and robust (heavy chewers) gracile Autralopiths though as bipedal apes with modified dentition, males usually larger, grew and mature rapidly. First gracile australopiths frugivorous shown by microwear tooth analysis, may have eaten some meat. Tracks of bipedal autralopithecus aforensis found (most known autralopith). Lucy is most complete pre-homo hominin fossil. Teeth and jaw very human like (cranial volume of A aforensi similar to chimps) Australopiths retained apelike features of limbs and semicircular canals of inner ear, retention of ape like orientation in arboreal environment. Long and curved toes and fingers also suggest arborealism. Hands more human like than gibbons. walked human like. Earliest autralopith is A. anamensis, intermediate between ardipithecus and australopithecus afarensis. Fossils associated with forest. Autralopithecus africanas had heavy arm bones suggesting more time in trees. May not be in the direct evolutionary line to homo. Autralopithecus sebida is closest of autralopiths to homo genus in both cranial and postcranial features. may have limited ability to eat hard food, setting stage for emergence of homo that lacks jaw structures associated with tough food. A. deyirimedia shows jaw and tooth features associated with austraopiths may have appeared earlier in fossil record. Also shows that 2 hominin species lived in the same region simultaneously. kenyanthropus platyops combines derived face with less derived cranium. Robust autralopiths appeared later than gracaile ones, specialized for eating plant material usually placed in own paranthropus genus. All robust australopiths were sympathic with early homo. Extinction mid-pleistocene related to climatic and vegetational changes. Used to be though that development of savanna habitats coincided with split of human lineage. Development of rift valley isolated humans. Then humans would have adapted to grasslands with bipedal gait. Now known that human bipedalism occurred before broad savanna expanses. Seems that it took place in forested environment. Gracile A. primarily pliocene radiation before savannas. Hominin lineage split in 2 at start of plesitocene and coincided with major climatic changes. One lineage was Homo and other was robust A. Climatic cooling resulted in reduced Robust A.

Bird flight

Flapping flight is automatic and unlearned in most birds. Don't practice. Birds in open nests may flap wings prior to first flight, but it's to develop muscle. Beating wing in flexible and porous yields to air pressure. Shape, camber, angle, and feather position all change. Aerodynamics of flapping not fully understood. Wings function as airfoils and propellers. Bird can't continue to fly straight unless it develops thrust to balance against drag. (from down ward stroke). Primary feathers at outer edge are site of generated thrust, secondaries generate lift. (on inner wing). Wings move downward and forward, each feather acts as a propeller and generates thrust. IN downstroke, thrust is greater than drag and bird accelerates. In small birds, return stroke (upward and backward) provides no thrust and is passive recovery stroke. Vortices (eddies of swirling air) play a major role in flight. Those formed at wing leading edge contribute to lift, but also increase drag. tail reduces drag by keeping air flow close to body. Wing vortices are left in birds wake and provide lift to following birds. Leaders work harder and often switch positions. Bird can change wing aerodynamics by extending them or sweeping back. (morphing). This modulates speed, turning rate, and glide angle. In landing, it spreads tail and extends feet to create drag. Raises underwing coverts (feathers) which maintain lift at low speed by increasing wing camber. alula (feathers on second digit) also extend to create a vortex to maintain lift. Contraction of pectoralis major produces forceful down stroke. Upstroke from contraction of supracolacoideus. Supracolacoideus inserts on dorsal head of humerus. In most species it is small with low myoglobin (easily fatigued). This muscle is larger for ones that rely on powered upstroke for fast take off, hovering, or fast aerial pursuit. Ration of the two muscles is an indication of reliance on upstroke. Wings differentiated by aspect ration (length of wing/area- higher in long narrow wings) and wing loading (bird weight/ wing area). High aspect ratio wings provide high lift to drag ratios in birds relying on dynamic soaring. Aerial forages have high aspect ratios and employ wing morphing to adjust speed and sinking rate for sharp turns (have flight profile- little camber and often lack slots). Many forest birds have elliptical wings (low aspect ratio) with many slots. They can't soar, but have rapid take off and maneuverability, generally have high wing loading with small wings and rapid flapping flight. Static soarers (eagles) have high-lift wings intermediate between elliptical and high aspect ratia. Have deep camber and slotting. Broad wings with low wing loading. Remain in air by gliding on air masses. Rarely flap wings. Slot enhances maneuverability, are individual feathers. In regions with rising air currents, static soaring is energetically cheap.

Warming and cooling

Greater latitudinal distribution of continents and changes in ocean currents resulted in cooling trends of north and south latitudes. Ice in south pole formed about 45 Ma, declining CO2 also contributed to cooling. Trend reversed by warming in late oligocene- early miocene. but further colling followed mid-miocene climatic optimum resulted in ice at north pole. Late cenzoic cooling resulted in a series of ice ages and interglacials. Cooler and drier ecosystems replaced tropical-like forests with woodland and grassland around 45 Ma. Early cenzoic still reflected "hot-house" of mesozozic, tropics hotter than present day. Increase in CO2 at starte of Eocene. (thermal maximum) probably caused by release of methane from shallowly buried sediments on ocean continental shelf. (aleocene-eocene boundary). Mammals responded to this by dwarfing (becoming smaller), later temp increase (eocene optimum) also resulted in dwarfing. Early eocene O2 rise to present day amounts could have favored larger placental mammals and modern orders of mammals appeared at this time. BY middle eocene, temps began to fall with CO2, causing "reverse green house cooling effect". Became as cold in high latitudes as today. Eocene temp an erin related to antartic ice sheets. Cold H2O massed over poles when greenland left norway, Australia left antartica, and antartica and SA breakup initiated formation of drake passage that separates them today. Transitory arctic ice present late middle eocene- early oligocene. Extensive antartic glaciation in oligocene, CO2 near prsent day. Drake passage deepened, antartic circumpolar current formed. Warm period late oligocene from isolation of cold polar water around ACC. (CO2 levels rose to neogene max). Further deepening of Drake passage expanded ice caps. CO2 declined again toward pleistocene low and cooling till present day. Miocene generally drier than paleogene (spread grass lands) Closing of isthmus of panama late cenzoic connected Na and SA. Warm H2O could not circle equator and gulf stream formed carrying warm water from subtropical america to western europe. Extensive glaciers in pleistocene. Ice ages and formation of arctic ice cap almost all of today's species originated here, along with humans. 4 major episodes of glaciation interpersed with 20 mini ones. Episodes caused by milankovitch cycles. Different cycles of variation in Earth's orbit around the sun, the tilt of Earth's axis, and amount of solar radiation reaching earth. When these 3 align, they have major effect. Dispersal routes for animals to g towards equator blocked by mountain ranges and narrow passages. Alaska, Siberia, and beringia were free of ice and housed mammoth steppe (steppe tundra) biome. Supported highly disperse fauna of large mammals. Drying of ice free portions due to volume of water in glaciers important for terrestrial ecosystems.

horns and antlers

Horns play roles in social recognition, sexual display, defense, and male territoriality. All horned ungulates are ruminant artiodactyls. Horns and antlers out growth from skull frontal bone, bony core with sheath of keratin, growth from base. Giraffids have ossicones, bony core not outgrowth of frontal bone, but fuses with frontal bone and covered with skin instead of keratin. Caribou have antlers, branched, consist of bone and shed annually. Covered with vascularized skin while growing, skin sloughs when mature. Mode of growth of these appendages different in artiodactyls, showing independent evolution. Rhino horns formed of only keratin, and single at midline unlike other ungulates. Some artiodactyl fossils show rhino like horns. Evolution of ruminant horns tied to social behavior. Ancestors first in oligocene, hornless, small, fruit diet, lived in eursian woodlands by early miocene. Changes in vegetation change food resources. Ruminants became larger and evolved teeth for more fibrous vegetation. New diet with more abundant leaves had smaller home range and became territorial. Territorial ruminants went from monogamous to polygamous. Intense male competition promoted horn evolution for social display. 3 lines of evidence consistent with hypothesis: timing of horn evolution, sexual dimorphism in horn occurrence, absence of horn in NA. Horns appeared in different ungulate families around same time, correlated with habitat change and increased body size. Today smaller ungulates still hornless. Horns evolved initially in males. Fossils show that early ungulate species had horned and hornless individuals. Presumed to be males and females. Suggest horns initially used in male-male interactions (not defense) NA ungulates are hornless. Grasslands replaced forests in NA without a persistent forest stage. In grasslands, ungulates unlikely to go through stage of territorial defense, leading to no sexual dimorphism. NA ungulates also hindgut fermenters (less efficient, needing larger home range). Horses and camelids have harem social system, here males defend females and no territory. In harems the basis is bond between females, which allow one male to join.

aquatic birds

some use a flying motion in water. Stage A: wings used for aerial flying only (gulls) Stage B: wings used for both submarine and aerial flying (diving petrels) Stage C: wings used for submarine flight only (penguins)

primate distribution

No first person, transition between species are not all of a sudden. Evolution is a very slow process. Origin of anatomical humans in Africa about 100000 years ago. For only about 1% of vertebrate history has included hominins. Only 5% of human history has included modern humans. First humans 5 ma, first modern humans 200 ka, first vertebrates 525 ma. Primate distribution changes since eocene. Across europe, asia, and NA. Now distributed over southern latitudes. Changes in skulls compared between apes and hominids, differences are tiny compared to differences in other skulls. Can still be visually seen.

selective feeding

Selective feeding depends on: vegetation type, species and group of plants, parts of plants eaten. Type of vegetation depends largely on habitat. Type I diet found more in forests where plant diversity and growth is high throughout year. Type II diet found in woodland/grassland, Type II found in savanna/grassland. Type II and II may move from place to place following rain. Type IV found in almost any habitat. Habitat and diet of antelopes put constraints on possible social groups. Type I feeder changes food distribution and eats everything quickly, making group feeding impossible, second individual can't feed right behind first, also lose track of each other in dense vegetation. Type I are solitary and places a premium on home range familiarity. Type II and II leave food for others to feed nearby, allow for herds of grazers together. These species move nomadically with rains, group size changes with resource distribution. Type IV also unselective that they readily form groups. Antelope mating system closely related to group size and food distribution (determines female distribution and potential males) Type I females are dispersed, males can defend food resources, but individuals must disperse through territory to feed. Not feasible to maintain a territory to attract females. Males tend to pair with one female and defends one territory . Offspring driven out. Type II groups contain males and females, only some males are territorial. Will claim a group. Type III males only establish territory when herd is stationary, then males have access to females. Unmated males for bachelor herds and fight for top. Type IV have male dominant hierarchy, hierarchy based on body size, individuals at top court receptive females, but no territoriality or harem. Female herd membership is fixed, resulting in degree of genetic relationship among herd members. Prey species can avoid detection, flee before attack, flee after attack, threaten predator. Body size, habitat, group size, mating system all determine risk of predation a species will face and predator avoidance methods. Small species tend to have more predators, small antelope can't run as fast, but can use cryptic coloring in forest habitat and use familiarity to flee. Groups more conspicuous to predators, but have more eyes to watch, avoid by fleeing (II). Type III are large with few predators and big enough groups to scare off predator. Wildebeests have synchronous birth, and can interrupt delivery to join mass parturition. reflects advantage of presenting homogenous groups of calves. Type IV are formidable, escape most predation because of size.

body size and sociality of antelopes

Species that are small and eat not as dispersed tend to live solitarily and hide from predators. Large animals that feed on food in abundance tend to form groups and migrate. This is both referring to herbivores. Diest closely related to body size and habitats. In turn, those relationships are important in setting group size, size of group determines female distribution, major factor in mating system. Body size is primary factor determining anatomical characteristics of gut of ungulates volume of rumen proportional to body mass of species with different body sizes. Metabolic rate proportional to body mass to the 0.75 power. Large ruminant has more capacity to process food than a small one. Metabolic requirements become very high in small animals. For mall animals, metabolic requirements become very high in small animal. For small animals, metabolic requirement become high in relation to volume of rumen to ferment plant material. Small ruminants must be more selective feeders. Must eat much more quality food than quantity and rely on obtaining more energy per unit volume from smaller food volume they can fit in rumen. Species over 40 kg can be unselective grazers. Type I species: selective browsers, feed on certain plant species on certain parts for highest quality diet and fruit (dik-diks and duikers), show little sexual dimorphism. Type II species: moderately selective grazers. Eat more plants than Type I, more seasonal changes in diet, exploit fresh fruit availability (impalas). Have substantial sexual dimorphism. Type II species: primarily grazers not selective for a specific type of grass, but selective for specific plant parts. Avoid grass that is too short (limits food intake) or too long (low quality), show little sexual dimorphism (wildebeest). Type IV species: very large and unselective garzers. Males larger than females (buffalo)

Placental diversification

Suggested that placental diversification occurred rapidly. Stem placentals thought to be contained to mesozoic. Early cenzoic order taeniodonta shown to fall on placental stem. Molecular data support division of placental mammals into atlantogeneta and Boreoeutherian. Southern lineages isolated from northern ones much of the cenzoic, molecular evidence suggests northern placental origin. Afrotheria are endemic african mammals. Paenagulata (hyraxes, sirenians (manatees), proboscideans (elephants)), molecular data also includes aardvark, elephant shrews, tenrecs, and gopher moles. This group came from long isolated evolution of mammals in Africa. Other african mammals came when africa joined eurasia, primates only extant long term african resident that aren't afrotheres , Sirenians, proboscideans and desmotylians grouping is tethytheria. Sirenians and desmotylians are aquatic, proboscideans have features to suggest semi aquatic existence (supported by teeth and myoglobin biology of extant elephants). Later proboscideans may show secondary return to terrestrial existence. Early proboscideans lacked trunks, so speculation that trunk was like early snorkel is incorrect. Xenerthra has 2 endemic SA orders. Pilose has sloths and anteaters, cingulata has armadillos. Xenarthrans known as edentated (no teeth), all have simplified dentition. Occurred NA since late miocene. Pangolins originally thought to be rlated to xenarthrans (morphological features), but just have convergent features from similar lifestyle, palidota sister txa to carnivora placed by molecular data. Boreoeutheria divided into euarchontoglires and laurasiatheria. Euarchantoglires divided into glires (rodents) and Eurchanta (primates, tree shrews, dermopterans). Molecular data place bats withing laurasiatheria. Laurasaitheria insectivores often considered basal stock for other placentals, but they aren't closely related to ancestral placentals. Tenrecs and golden moles belong in afrotheres. Remaining insectivores placed i order eulipotyphla. Largest grouping in laurasiatheria is fereungulata, comprised of carnicvores and ungulates. Ungulates (hoofed) include artiodactyls (even toed) and parissodactyls (odd toed), probably sister taxa. Don't know where to place with carnivora and pholidotata. Some archaic ones were omnivores/carnivores (mesonychids). Severa; hoofed orders extinct in SA (litopterna and notoungulata placed with perissodactyls) cetaceans found to be ungulates, related to artiodactyls, often put in single order together in cetartiodactyla. Carnivore distinguished by specialized shearing teeth (carnassials) from last upper premolar and first lower molar. Includes myrmecophagous aardwolf, aecondarily herbivorous forms (panda) and pinnipeds (seals) Pholiodota comprises 8 species of pangolins (scale covered myrmecophagous mammals from Africa and South Asia). Terrestrial and arboreal species that feed on ants and termites. Tear open nests with large claws on forefoot and gather with sticky tongue by muscle that extends back to pelvis.

Therapsids

Therapsids flourished middle permian- early cretaceous. Dentition had incisors, canines and postcanine teeth. choanae (internal nostrils) enlarged and trough in roof of mouth (possible covering of secondary palate) indicates dedicated airway passage separation from oral cavity, which started reflecting tension of caudofemoralis muscle. Seen in reptiles. Therapsids reduced those processes, but had more expanded ilium and greater trochanter on femur. Showing switch to predominant gluteal muscles. With changes in posture and musculature came short tail and intratarsal articulation between astragulus and carcaneum in ankle (more upright gait) Therapsid feet were shorter, showing use as levers in limb-based locomotion. All tetrapods have 2 phalanges on first digit, primitive amniote had 3-5 phalanges on other digits, 4 being longest. mammals have only 3 other digits, which was seen in early therapsids. Pectoral and pelvic girdles less massive than pelycosaurs. Slender limbs, shoulder joint allowed more movement, allowing larger stride. First appearance in middle permian, may have evolved in drier tropical regions an terrestrial plant diet. Pelycosaurs were in aquatic ecosystem in equitorial regions with rainfall/ Extinct as sea levels rose. Therapsids were in temperate zones in ate permian. Generalized terrestrial forms radiates into carnivores and herbivores. Cynodont lineage gave rise to mammals. Therapsids dominant large land mammals later permian. (herbivorous anomodonts and carnivorous theriodonts). anomodont had long fingers and toes- arboreal or elongated teeth for display. Saberlike canines seen in gorgonoprid (theriodont) related to diet. One lineage had a grooved canine with a pocket shown to be for venome. Dicynodonts (anamodant) most abundant large terrestrials late permian. Only lineage with cynodonts to survive end permian extinction. Might be due to high bone growth rates and reduced vulnerable juvenile period. Diversified into many ecological types. Skulls for herbivory had loss of marginal teeth with turtle like horny beak to cut vegetation. Disappeared end of triassic. Eutheriodonts (therocephalians and cynodonts) major predators late permian to earluy triassic. Coronoid process of dentary in jaw for larger insertion of jaw closing muscles and lever arm for action. temporal fossa enlarged. Evidence of maxilloturbinate bones, respiratory turbinates, used to warm and humidify incoming air and reduce H2O and heat loss (also evolved independently in dicynodonts) Discynodonts and cynodonts diversified early triassic. Diapsid reptiles gave rise to dinosaurs. Therapsids minor component of terrestrial fauna in triassic. Most non-mammalian cynodonts extinct by end triassic, trithylodont and tritheredonts persisted. Basal cynodonts flourished early triassic, more derived eucynodont late triassic split into cynognathians and robainognathia. Cynognathians predominant middle triassic with high rate of diversification. Carniverous cynognathas and herbivorous gomphodonts. Probainognathians were smaller and less diverse. Prominent late triassic and eventually gave rise to mammals. Cynodont had mammal like derived features. Enlarged dentary and reduced postdentary. Masseteric fossa indicates mammal like masseter. Bones from lower border of synapsid temporal opening bowed out into zygomatic arch, accommodates masseter. All cynodonts had multicusped cheek teeth with evidence of some occlusion (contact when biting), suggesting more powerful and precise bite. Enhanced for manipulation and resistance to fracture. Complete bony secondary plate. More derived cynodonts had enlarged infraorbital foramen implying highly innervated face, mobile muscle with lips and whiskers. Vertebral column differentiated into thoracic and lumbar regions. Hindlimbs almost fully mammal like with expansion of iliac blade, reduction of pubis and ischium, development of colluneal heel for achilles tendon, and development of curotarsal ankle between proximal tarsals and lower limb. Cynodont evolution characterized by body size reduction.

human tool use

Tool use estimated in less than 1% of non-human animals (passergine birder and primates) Many primate lineages use tool, like rocks to open nuts, sticks to reach food. Tools for food acquisition seen in chimps, orangutans, gorillas. Captive bonobos use tools. Manipulation and preparation of tools limited to hominins. Earliest simple tools predate species of homo (lomekwian tools 3.3 ma). oldowan tools were circular (2.7 ma). Oldowan tools standard for many years, replaced by acheulean tools 1.76 ma. Have long axis and chipped on both sides. Made by h. erectus. Lack of advances in tool manufacture. Surprising with spread of tools. Assumed that evolution of tool use and culture was in context of hunting. Archaeological evidence for hunting in early hominins suggest early humans were scavengers, occasionally cannibalistic. studies of a few hunter-gatherer societies show that hunting and gathering shared by both sexes.

anthropoids

anthropoids are larger than promisians, with larger brains and small olfactory lobes. Mainly frugivorous or folivorous. All are diurnal with complex social systems. Large ones employ suspensory locomotion (body hanging below branches). Specialized form is branchiation (swing from one branch to next using hands) Modern ones distinguished from promisians by skull features like larger brain case, fusion of many paired bones, shorter snout. Bony postorbital septum prevents mechanical disturbance of eye when temporalis muscle contracts during chewing. Lack grooming claw on second toe that promisians have. Origin related to shift from night foraging for diurnal, accompanied with reduction in body size. Eosimiids established as stem anthropoids. (earliest anthropoids early eocene) Platyrrhine and catarrhine are modern anthropoids. Old world (narrow nosed are monkeys and apes (catarrhini). New world (broad nosed) are monkeys (platyrrhini). All catarrhines have trichromatic color vision. Produced by duplication of red-green opsin gene. Seen only in a few platyrrhines Platyrrhine have retained good sense of smell with most olfaction genes functional. catarrhines still lost vomeronasal and have 50% functional olfactory genes. Enlargement of brain occurred independently in platyrrhines and catarrhines. Platyrrhines retained 3 premolars on both sides of jaw, catarrhines only have 2. Platyrrhines first appeared in SA and are exclusively new world radiation. Presumed to raft from Africa across narrower south atlantic. 3 lineages: pitheliids, cebids, and altelids. pithelids include sukis and titis. Sukis have features for eating hard foods. Titis have complex vocalizations. Some think that titis are most primitive new world monkeys, but molecular analysis put them closer to ptheliines. Cebids include marmosets and owl monkeys. Active arboreal quadropeds that eat fruit and insects. Capuchins are only ones that retain prehensile tail as adult. Marmosets have secondary claws on all digits except big toe, simplified molars. Owl monkeys are only nocturnal anthropoids. Atelids include spider monkeys and howler monkeys. Distinguished by prehensile tail and use of branchiation aided by tail. Male howler make loud calls due to enlarged hyoid bone that houses a resonating chamber. Atelid and cebids only non-human primates north of panama. Spider monkeys and gibbons both ar especialized brachiators with exceptionary long arms and evolved convergence in wrist joint modification to allow rotation. Spider monkeys just use their tail as a fifth limb. Catarrhines include apes and humans. Stem catarrhines include propliopithecids a nd priopitheids split. between apes and old world monkeys estimated around 28 MA. Have nostris that open forward and downward. Smaller bony nasal opening from skull than platyrrhines. Great apes and humans are largest extant primates. Evolved 2 clads: old world monkeys (cercopithcoidea) and apes and humans (hominidea) Old world monkeys include colobines and cercopithecines. Colobines include langurs and colobus monkeys. More folivorous than cercopithicines, have higher cusped molars and complex forestomach for plant fiber. Primarily arboreal with long tail and hindlegs longer than forelegs. Cercopithecines primarily african (baboons and macaques). More fruigivorous reflected in broad incisors and flat bunodont molars. More terrestrial, often with shorter tail, fore and hind limbs of equal length. Have cheek pouches to carry food, long thumb and short fingers. First old world monkeys appeared around apes in oligocene. Radiation in late miocene and pliocene coincided with reduction in diversity of earlier ape radiation. Apes originally more generalized forms. Extant radiation of cercopithecoids is more derived than apes. Humans are apes.

apes

apes and humans placed in hominoidea. Distinguished by widening and dorsoventral flattening of trunk. Shoulders, thorax, and hips proportionally broader. primates included in monophyletic hominoidea date from late oligocene. Modern apes are highly specialized radiation of large tropical animals. Apes in miocene radiated into temperate parts as well, Monkeys have lower molars with 4 cusps, apes have 5. Ape teeth have lower cusps and grooves between posterior cusps. Pes include gibbons, siamang, orangutans, and chimpanzees and gorillas. Distinct cultures and tool use seen in chimpanzees. Chimps are endangered. Gibbons move through tress by brachiation and become bipedal on ground, outstretching arms for balance. Smallest apes, differ in monogamous social system. Male and females produce combined calls to strengthen bond and act as territorial calls. Usually live in separate populations, but different species occasionally hybridize. 3 species of orangutans. Extremely sexually dimorphic (males weigh twice as much). Arboreal, but rarely swing by arms, prefer slow climbing in branches. Move all four limbs to grasp branches, sometimes walk bipedally on a branch. Move quadropedally on ground, close hands into fists for support. Generally solitary, a group will only contain a female and offspring, individuals call for social contact. Use tools for tasks such as umbrellas, leaves as cups, sticks for scratching and getting seeds. Gorillas and chimps live in tropical forests, more terrestrial then gibbons. Both move quadropedally with knuckle walking on ground. Gorillas support themselves on dorsal surface of digits 3 and 4 rather then fists like orangutans. Hand and wrist aligned in gorilla knuckle walk and chimps have a flexed wrist. Gorillas are largest and most terrestrial extant ape. Highly social and live in groups. Sexually dimorphic in size and most folivorous ape. Use tools for food acquisition and social displays, but do not have population specific culture. Gorillas leave their groups when they reach adulthood. Chimps are more arboreal than gorillas with suspensory locomotion. Only moderately sexually dimorphic and live in groups, small groups coalesce into a larger group and they split into smaller groups related to abundance and distribution of food (fission-fusion pattern) 2 species of chimps: common chimp (gambe) and bonobo (live in forested habitats) Common chimps use tools and bonobos don't. Meat significant component of chimp diet, but not bonobos. Adult males will engage in cooperative hunts for red colobus monkey. Males in tree with females on ground. Chimps are very territorial with rigid male dominance structure and frequent aggression. Bonobos are female centered groups and don't engage in aggression, less sexually dimorphic. Genital swelling signals estrus in female chimps, but female bonobos have concealed ovulation and continuous sexual receptivity. Bonobos use sex as a conciliatory behavior for bonding and conflict solving. Also have same se sexual repertoire. Chimp populations show different combinations of behaviors.

earliest hominids

earliest hominid fossil from late oligocene, belonging to rukwapithecus. Early hominids primarily arboreal. Bundont molars for frugivorous diet, more derived that propliopithecid stem anthropids. Late miocene included proconsulines, afropithecines,a nd myanzapithecines. Early hominids lacked tail. procosulines ranged in size, generalized arboreal quadrpeds, hands and feet more capable of gripping with longer thumbs and stable elbow. Moropithecus first hominid to show features of skeletal anatomy for suspensory locomotion. (highly mobile shoulder, stiff back that resisted flexion in lumbar, moderately mobile hip) Middle miocene: aropithecus, kenyapithecus, equatories remaine din africa. Probably basal homnids, placed withing aropithecidae. Ceropithecine and colobine monkeys in eurasia late miocene. Following warming and connect of african and eurasia. Late cenzoic eurasia apes: sivapithcins and dryopitheches. Both more derived than hylobatids and in homnidae. Last ancestor of hominoids may have been more gibbon like as suggested by pilobatel fossil. dryopithecines diversified in europe, considered sister to extant hominids. Sivapithecins mainly asian and stem stock for pangines (orangutans). Primarily in forests with suspensory locomotion. Flourished in cooler climate of miocene. Both groups included several genera. Eurasian drypithocine include drypithecus, hispanopithecus, ouranopithecus, anoiapithecus, rudapithecus, graecopithecus, oleopithecus, rufengpithecus, pierolapithecus. Plethora of eurasian apes cited as arguments for hominae eurasia origin. However, miocene apes appear to be stem hominae (absence of hominoids in africa 13.5-10 ma) Conditions in forests not good for fossils of chimps and gorillas. Humans retained numerous dentala nd cranial featured of clade. All extant hominids are derived compared to miocene- pliocene are radiation. Gibbon and orangutan basal positions on phylogeny just shows that both are arboreal specialists.

human brain

human brain increased in size with prefrontal cortex (small olfactory bulbs). speculated increased social interactions. Conceptual complexity, tool use, and language Selective pressures for larger brains only satisfied in environment that provides energy, especially to pregnant/lactating females. Required to increase foraging efficiency (achieved through larger females) and high quantity of quality foods (use of tools and fire) Large brains required change in life history with slow rate of development, lowering energy demands and reducing female reproductive output. When did brain get big both in absolute and relative size? Human brains larger than any other groups. Study suggests that H. erectus did not have big brain. H. erectus infant skull allowed looking at brain size at early age. Could explore growth trajectory of brain. Growth trajectory of H. erectus fit in with growth trajectory of chimps. Reach adult brain volume at earlier age than humans. Concluded that H. erectus brain growth trajectory closer to that of apes, human large brain size is very recent and must have evolved after diverged from h. erectus. Large human brain energetically expensive. Diet change required before formation of big brain. Hypothesis that cooking evolved before large brains. Human brain is still constantly evolving.

sociality

state of living in structured groups, and some group living is found among all kinds of vertebrates, greatest development of this is found in mammals. Mammals may be social due to the interaction of many different characteristics (relatively large brain to facilitate complex behavior, prolong association of young and parents, high metabolic rates and endothermy) More species of solitary in mammals than social ones. Sociality interacts with other kinds of behaviors, morphological and physical characteristics, distribution of resources.

human bipedalism

humans distinguished by bipedal stance and locomotion, enlarged brain, capacity, for speech/language. Only hominins display erect bipedal mode of striding locomotion involving specialized pelvis and hindlimbs. Fee forelimbs from functions of support, balance, and locomotion. S-shaped curve of vertebral column, modification of pelvis and acetabulum position, lengthening of leg bones, shift knee angulation toward midline. Hue longer trunk region with barrel shaped rib cage and distinct waist. Waits may allow for independent pelvis rotation. Secondary curve of spine us consequence of bipedalism. Form when infant learners walk. Have not perfected spines for stress of bipedalism. Stand in knock-kneed position, allowing walk with feet at midline, reduces hip rolling. This can aid in determining if something is fully bipedal. Leaves some signatures at the articulation of femur with hip and at the knee joint. Makes humans prone to dislocate knee. Women with wider hips have femur inclined at more acute angle towards knee. Feet become more arched with changes inn shape and position of tarsals and with close parallel alignment of all 5 metatarsals and digits. Big toe no longer opposable and much larger to bear weight of stride. Basal apes walk with upright trunk adapted for arboreal locomotion makes them like this. Wild orangutans walk bipedally in trees, supporting by grasping branches overhead. Shows bipedal walking could have evolved in trees. Consistent with ardipithecus mixture of features suggesting bipedalism and arborealism. When did bipedalism evolve? First in australopithecus with footprints found. Bipedalism needed for altricial babies to carry them. Altricial growth required for large brain, so they can have longer brain growth. Bipedalism evolved in forested environment. Can't say that it's for an altricial baby, because that implies that evolution has foresight. Movement to African savannas happened by climate change forming isthmus of panama, but humans evolved bipedalism before that. Could be bipedalism be for thermoregulatory reasons? To see predators? but that all might be more useful for a savanna, but we don't even know when Africa savanna spread.

human loss of body hair and pigmentation

humans lost body hair and pigmented skin heavily. These are related features, pigment protects skin from sun, originally done by fur. Have same # of hair follicles as other apes, but hairs are miniscule. Speculation for hair loss include increased use of sweat glands, increased problems with skin pericytes. (maybe in association with sedentary lifestyle among groups of people) Genetics for skin pigmentation date to 1/2 ma suggesting hairiness in lineage leading to H. sapiens, maybe even H. erectus. Corresponds with adoption of home base in hominins, making more prone to parasites. Maybe shared hairiness with neanderthals. Genetics of skin parasite shows start of clothes wearing. Human body louse clings to clothes instead of hair. Body lice evolved from head lice around 70 - 40 ka. Coincidence with emergence of H. sapiens in europe. Humans with different ancestries harbor distinct lineages of parasites. Humans from close to equator have darker skin, which is a balanced between protection from UV light and need for vitamin D. Folic acid essential for development, and gets broken down by UV rays. melanin blocks penetration and protects folic acid. Compromise of enough melanin to protect folic acid while still permitting enough UV to synthesize vitamin D.

mammal studies on food

mammal studies concentrated on food as paramount importance. Vertebrae energy consumption in creased with body mass. Can predict that home range size increase in proportion to body mass. Home range size is proportional to body mass to the first or second power. Relationship between energy requirements and home range suggest that energy needs are more important to determining home range size, but additional factors involved (efficiency with which animal finds resources may decrease as home range increases). Home range would be expected to increase with body size more rapidly than energy requirements. Assumption that resources are evenly distributed overlooks most habitat complexity.

Therians musculature and bones

main difference between therians and non therians is being viviparous instead of egg laying. Therians lost sclerotic bony rings around eyes common in other amniotes. Monotremes retain sclerotic cartilages, but do not ossify to form bony rings. Detrahens is jaw opening muscle in monotremes, digastric is in therians. Different histories of turning articular bone into malleus. Therians have tibosphenic molars that can crush and shear food. Therians have reduced and fused cervical ribs with cervical vertebrae. Therian elbow joint modified from generalized amniote joint that allows some rotation. More pronounced olecranon process forms triceps lever arm to push fore foot off ground. analogous to calcaneal heel. Decreased flexibility of elbow, but can protonate to allow more erect stance. Monotreme shoulder girdle like reptilian condition. Ventra midline interclavicle anterior to sternum, large corcoid linking interclavicle and sternum to scapula. Therians lost interclavicle and reduced coracoid to a process fused with scapula. Reduction allows glenoid fossa to orient downward rather than more laterally, more adducted posture of therian forelimbs. Shoulder joint of therians have greater motion and les sstability tahn monotremes. Humerus held in place by muscular action. Scapular spine divides blade into portions, base of spine extends out from body into acromion process. (clavicle articulation). Clavicle retained in most therians and lost in many running placentals. Scapula moves independent of limb, adding to stride length. Muscle that rotate and come from cervical vertebra. Tetrapod humerus protractor and suprcorcoideus modified into suprasinatus (stabilizes humerus) Monotremes have derived mammalian pelvis with reduced pubis, epipubic bone, and rod shaped ilium (inverted U). Therians have U- shaped articulation with femoral head in acetabulum reflects increased hind limb importance in forward propulsion. More adducted femur position. Astragalus of therians superimposed farther on calcaneum that generalized mammal condition. Ankle joint more lever like. Therians have pronounce heel that increases lever arm. Further extent of astragalus superposition evolved convergently in placentals and marsupials. Therians adopted new rapid gait: smooth, continuous bounding. Push off from hind limbs; dorsoventral flexion of lumbar spine and scapula rotation with extended forelimbs increase bound length. Rotation of scapula with tucked elbows also extends stride length. Scapular sling muscles cushion impact on landing, flexion of lumbar spine brings back legs forward for next bound. Highly dependent on flexed spine and limbs that pivot from top of scapula/hip joints and bend at shoulder/knee/ankle/elbow joints in small mammals. Independent scapular movement is critical. larger mammals move with stiffer back and straighter legs in galloping. Multituberculates convergently evolved a type of bounding gait (reduction of coracoid) retained monotreme like abducted limb posture, probably has ungainly frog like jumping. Mau have a limit on body size.

mammalian teeth and jaw

mammalian teeth show extensive variations for differences in feeding and diet. canines often lost in herbivores, but can be used in defense (tusks). Upper canines generally larger in males. Molars of carnivores usually have 3 pointed cusps., omnivores have reduced cusps for grinding. Added 4th cusp to upper molars and increased size of tulonoid basin in lower molars (bunodont). In herbivores, simple cusps of bunodont tooth run together in lophs. Work best when loph exposes dentine. Loph consists of sharp enamel ridges when teeth occlude and jaw moves laterally, food is grated between shearing blades, lophed teeth evolved convergently many times. Selenodontmolars (crescenic lophs anterior-posterior) seen in ruminants and leocerus. lophodont (loph run cheek to tongue) seen in perissodactyls. elephants and wombats have multilophed or lamellar molars. Herbivorous mammals face a problem with diphyodonty because they have highly abrasive diets. Grazing mammals have high-crowned (hypsodont) cheek teeth. Have very deep dentary bones and maxillae and crowns of teeth extend deep into bones. Cementum covers entire tooth and base of crown. Hyposodont teeth erupt from base to provide continuously renewing occlusal surface. Some small mammals have hypserodont molars (roots don't close and tooth is ever growing) as dentine wears, it is renews a sharp blade of enamel at tip. Elephants have a novel feature of molar progression. Each molar is hypsodont and enlarged. When molar is worn it's stub falls out front of jaw and molar behind erupts from back to replace it. In carnivores, incisors seize food, canines stab prey, carnassials slice through flesh, molars break food into pieces. herbivores have lost incisors, post canine teeth are for mastication and premolars are like molars. Herbivores have long snouts and gap between incisors and cheek teeth called diastema. Function of this is uncertain. Large temporalis muscle is typical of carnivores for use of incisors and canines (large gape) Occipital region high in carnivores, strong muscles for retraining prey run to cervical vertebrae. Herbivorous mammal skulls have a masseter to exert crushing force at back of tooth row and moves jaw from side to side to help complex molars rupture cell walls. Posterior part of lower jaw for masseter is large, coronoid process and temporal fossa are small. Fairly low occipital region and lack powerful muscles. In many herbivorous placentals, cartilaginous partition of bark of orbit ossified and forms bony postorbital bar, probably important for absorbing jaw stress and protecting braincase. In carnivores, the jaw joint is on the same level as tooth row and teeth come in contact sequentially. Well suited for cutting and searing. Post glenoid process prevents temporalis from dislocating lower jaw. In herbivores, jaw joint is high on skull, brings teeth together simultaneously and grind. Rodents upper and lower tooth rows are same distance apart, unlike most animals where lower teeth are closer together. Rodent dentition combined with rounded jaw condyle to allow forward movement. Insertion of masseter is further forward so that lower jaw can be puled in occlusion. Allows rodents to chew on both sides at once.

Other benefits of sociality

mammals derive other sociality benefits like reproduction, care of young, avoiding predation, and facilitating feeding. Reduced predation risk when individual is in a group, 3 forms of this: group of animals can detect a predator more quickly due to more eyes, ears, and noses to keep watch. Can devote more time to feeding and less time watching for predators. Group mammals tend to live in open habitats, and solitary live in forests. Presence of a large # of potential prey may exceed predatory capacity if prey only present for a limited amount of time. Confusion for predator when trying to single out individual in a group may also increase likeliness of escape. Selfish herd hypothesis: individuals in center of a group are more protected that those on periphery. Large social mammals can form a defensive wall when predator approaches. Protecting those in center. Group living gives opportunity for alloparental behavior (care provided to young by individual that is not a parent) Non breeding individuals will join and help protect young as well. This behavior also extends to care of sick adults. Nonbreeding helpers may increase own fitness by assisting rearing of offspring of kin.

mammal scrotum

mammals have a scrotum to descend testes: may be better due to better sperm development at lower temp? Could be that sperm development is better at a lower pressure? Perhaps advertises fertility to females as a sexual selection?

Kemp's Ridley Sea Turtle

only one natural nesting site for these turtles, were in decline an don brink of extinction. Researchers established new nesting site for turtles, but in new nesting site, almost all hatchlings were males. Used info. about temp dependent sex determination to help more females be born. Factors that effect species extinction risk: body size, diet, habitat tolerance, geographic range size, hunted, legal protection, cross international boundaries, tolerant to humans, gestation and reproduction rate, litter size, place in food chain.

hominin coexistence

past 27 ka has only one species of hominin. Although, several species coexisted in history. H. erectus disappeared 150 ka- 40 ka years ago. H. sapiens lived with neanderthals, denisovans, and h. floresiensis at one point. Interbreeding in last 100 ka from multiple homo species in an area. Denisovans even bred with and unknown population of hominins to be discovered. Potential offshoot of asian H. erectus. 1-3% of genetic material in populations outside of africa are neanderthal. One person from romania had 6-9% (neanderthal ancestor 4-6 generations back). Neanderthal archaic genes boost immune response, define cranial morphology, linked to diseases like depression, skin lesions, blood clots, and urinary tract disorders.

evolutionary trends of hominins

several evolutionary trends in hominins. Points of vertebra and skull articulation and foramen magnum shifted to under the braincase from rear. (appearance of upright posture), braincase and forebrain enlarged, prominent verticle forehead developed by middle pleistocene, brow ridges and crest for muscle origin on skull became smaller with reduction in muscle size, nose prominent feature of face with bridged tip, jaw is soorter, canines smaller, gap between incidsors and canines disappeared.

H. sapien origin

single african origin of H. sapiens now supported by fossil record and genetic studies (specifically evolution of mitochondrial DNA and Y chromosome) Mitochondria DNA inherited from mother (cytoplasm of egg). allows tracing of maternal lineage. all living humans trace mitochondria to a woman who lived in Africa (african eve). Y chromosome can trace paternal lineage, but more difficult to study, indicates all human males descend from a single male 59 ka (african adam). Both studies indicate common ancestor from africa more variation of human genome in africa than anywhere else. Humans have 1/10 variation of chimps, indicating possible bottleneck of small population. earliest H. sapiens estimated 300 ka and widespread across africa. Humans spread from africa: crossed into levant region of asia (middle east), single major dispersal of non-africans across eurasai, australasia in 73 ka, reach australia by 65 ka, humans arrive in siberia 48-44 ka, greater asia 40 ka, eastern asia 39-36 ka, northeast asia 20 ka. Modern humans arrived in europe 45 ka, went through bottleneck during last glacial max about 25 ka with evidence of major population influx. Genetic, archeological, and environmental evidence place humans in americas 15 ka. Ice free corridor connecting beringia with NA closed 23-13.4 ka, implying humans had to take coast. Recent studies propose older arrivals in yukon of southern california (mainly based on scratch arks possibly from tools) older data suggests "replacement hyothesis" in which H. sapiens and evolutions replaced other homo species they encountered. Genetic studies reveal low levels of interbreeding between homo species as spread from africa. Asia populations have a higher percentage of neanderthal DNA. Humans probably interbred with neanderthals in middle east. Later they bred with denisovans in asia. This interbreedingdoesn't discredit replacement hypothesis (>90% of genome represent african origins), but calls for modification. "replacement with hybridization" or "leaky replacement" hypothesis.

human language

use of symbolic language is unique to humans. first evidence of writing 3000 years ago. Controlled speech may not be possible until late stage of H. erectus. Spinal chord of H. erectus much smaller, suggesting lack capacity for neural control of intercostal muscles that allow breath and talk control. Hypoglossal canal (exit for CN XII of tongue) is smaller than in humans and neanderthals. FOXP2 (involved in language production) has same differences as chimps. More derived H. Sapiens wouldn't be able to produce a range of vowel sounds until change in pharynx and vocal tract. Larynx originally high at base of tongue. Lower larynx provides larger resonating chamber. This is associated with change in skull base. Change in larynx position assumed by skull anatomy. Fully modern condition of vocal tract not a feature until H. sapiens. Speech needs neural change in order to process rapid frequency of sounds and decode. Leads to increase in volume around temporal area and isn't seen in neanderthals. Descent of larynx means original mammalian seal between palate and epiglottis lost, making humans especially vulnerable to choking. Also associated with sudden infant death syndrome. Perhaps other reason for larynx descent besides vowel sounds. On advantage is ability to voluntarily breath through mouth or nose. Distinct ability of humans to do spoken language and make vowel radiating sounds. Humans can do this because of ventral shift of larynx to provide resonating chamber. This makes choking more likely and shift occurs around time when sudden infant death syndrome is more likely. Ventral shift also allow choosing to breath through, mouth or nose, could be that larynx shift is driven by cold virus evolution. Language could be a biproduct.