BIO 370 exam 3

Ornithomimosaurs

"Bird-mimicking lizards" • Relatively small size • Long neck • Clawed forearms, three digits • Beaks and feathers appear in some lineages

T-rex might have been the opposite!

"Many paleontologists now think that the females of this species were significantly larger than the males. What this implies, in evolutionary terms, is that females competed for the right to mate with available males, and may have done most of the hunting as well."

Flight adaptations

(a) Lightened • hollow bone, feathers, no bladder, 1 ovary • except diving ducks (need to sink) (b) Large flight muscles: • can account for 30-60% of all body muscle! • leg muscles enlarged in predatory raptors (c) Superior respiratory performance • large heart, air sacs 1. Streamlined body 2. Myoglobin (oxygen-binding protein) enrichment in aerobic muscles • Red Muscle • White muscle • Bird pectoralis muscles 3. Wings are airfoils and propellers (can change angle of attack)

Interbone/Intrabone Isotopic Variation

1) Determine the mean temperature difference (difference between warmest core temperature and extremity temperature) between each skeletal element 2) Determine if the mean temperature difference increases towards the extremities 3) Determine if trends in temperatures are colder toward the extremities 1) Bradymetabolic mass homeothermy - intrabone variability increasing distance from the core becoming more positive 2) Ectothermy - heterogeneity of the ribs and dorsal vertebrate also exceed 1-2‰ 3) Endothermy - Intrabone isotopic variability of limb and tail is similar to that of bones from the body core and the interbone isotopic variability is small (~1‰) T-rex Data: suggestive of bradymetabolic

Were dinosaurs social creatures?

1) Display structures: - hadrosaur crests, ceratosaur frills, etc. 2) Sexual dimorphism: - hip size larger in female, crests and horns larger in males indicates male-male competition for females; i.e. horns on triceratops, bone heads - medullary bone onlyfound in female birds 3) Juvenile development goes through several changes in morphology indicating the ability to distinguish between juveniles and adults in a social group 4) Multiple dinosaur fossils found together in mass death assemblages provides evidence they were living in groups 5) Parental care and nesting behavior 6) Trackways indicate herding behavior

Mammalian Synapomorphies

1) Lactation by females with mammary glands • mammary hairs in monotremes • nipples in therians with the number of nipples in placentals being correlated with the number of offspring per brood • male mammary glands are absent in marsupials, but present in monotremes and placentals 2) Long bone epiphyses fuse at the end of development establishing determinate growth • epiphysis is separated from the rest of the bone by a growth plate where the elongation takes place. • epiphysis disappears at maturity and the bone cannot grow any longer 3) Suite of skull features • dentary squamosal joint • heterodonty (multiple tooth types) • diphyodont (2 sets of teeth) • milk teeth replaced with permanent teeth • only mammals masticate their food 4) Postcranial Skeleton • seven cervical vertebrate • atlas and axis shaped to allow the head to move up and down and laterally • no lumbar ribs (only thoracic) • spine can be twisted laterally and dorsoventrally (why?) Hypotheses 1) Allows for mammals to lie down on their sides, something not seen in other groups of vertebrates 2) Co-evolution with suckling on nipples that are located ventrally 5) Hair, glands, and skin a) Skin divided in 3 layers • Epidermis • Dermis • Hypodermis b) Skin contains nerves • Pain • Touch (Pacinian corpuscle) • Pressure (Meissner's corpuscle) • Temperature (cold and heat receptors) c) Several types of glands Eccrine glands - watery secretion • used for thermoregulation (perspiration) Sebaceous glands - oily secretion • used for lubrication and waterproofing (sebum) Apocrine glands - secrete volatile chemicals • humans - armpits and pubic regions • used for chemical communication (pheremones) Scent glands - secrete various chemicals • modified sebaceous/apocrine glands • used for territory marking or defense d) Hair • used for insulation, camouflage, tactile sensation • some mammals shed annually e) Other skin related integuments • keratinized digits or forehead appendages • claws, nails, hooves, antlers 6) Adipose Tissue • source of energy • mechanical cushion • endocrine function Two types • White fat • Brown fat • present in high amounts in infants and hibernating mammals • some in adults • lot of mitochondria • high energy production rate 7) Red blood cells lack nuclei • carry more hemoglobin • smaller so capillaries can be smaller (why?) • but cannot divide, so need to be constantly replaced by being produced by bone marrow 8) Muscular diaphragm • separates thoracic and abdominal cavities • essential for respiration

Main factors influencing mammalian diversification and distribution during the Cenozoic

1. Dinosaur extinction (Cretaceous) 2. Continental mass fragmentation and movement Mesozoic: • Pangaea breaks down into separate land masses • Land masses moving away from the equator and toward the poles Late Cretaceous/early Cenozoic: • Continents approach current positions • Land bridges exist between N. America and Asia and between N. America, Greenland, and Europe • India is moving toward Eurasia, collides to form Himalaya Mountains • Australia separates from Antarctica, drifts northward • New Guinea remains close to Australia - modern faunas still share many features 3. Climatic changes Cretaceous and early Cenozoic • Very warm, Paleocene Eocene Thermal Maximum (PETM) one of the warmest geologic times • 30 degrees Celsius average global temperature Middle to late Cenozoic • Gradual cooling of earth climates to an Ice House World • Cooling culminates with ice ages during the Pleistocene

Synapomorphies of Extant Birds

1. Elongate, mobile, S-shaped neck 2. Tridactyl foot (three toes forward, one backward) 3. Digitigrade posture (toes support weight of body) 4. Intertarsal ankle joints (rather than between tarsi and leg bones) 5. Pneumatic bones (air-filled) 6. Furcula (fused clavicles) 7. Fused sternum 8. Feathers and flight Conserved features a) feathers b) oviparous c) endothermic d) flight (may be secondarily lost) e) bipedal (with wings) f) beak g) small size (no more than 150 kg) Variable attributes a) feather morphology b) nesting habits c) environment selection d) locomotor speed/lift e) foraging mode f) body size (2 g - 150 g)

Dispersal: Marsupials

1. Metatheria (Marsupials + ancestors) originate in Asia during the Cretaceous 2. Late Cretaceous (70 mya): migrate from Asia to North America 3. Then spread to South America which is connected to North America (no competition with placental mammals, but there are large birds and crocodiles) 4. 65 mya: All N. American species go extinct and N. and S. America become separated 5. Then spread to Antarctica (Hot House World; still ice-free) and Australia about 50 mya 6. Pleistocene (2 mya): closing of Isthmus of Panama forming a land bridge between N. and S. America again

Mesozoic = "Age of Dinosaurs"

1. Permian/Triassic: Extinction leaves a vacuum ...which can be filled with new vertebrate forms allowing for evolutionary novelties to arise. 2. Triassic: Decrease in atmospheric O2 concentration creates hypoxic conditions ...which favors higher efficiency of respiratory system. And....crocodiles and birds have unidirectional flow of air through lungs which is more efficient than bidirectional mechanism. So, parsimonious that this was possible in extinct Archosaurs. 3. Triassic/Jurassic: Gradual drying of climate and temperature variations ...which favor animals that are good at water conservation. And archosaurs produce eggs with a hard shell which provides better protection against desiccation...plus bird and crocodiles produce uric acid. So, early archosaurs were better equipped to survive climatic variation. 4. Jurassic: Further decrease in O2 + increase in CO2 ...which favors plant productivity which leads to extensive food resource availability and possibly favors evolution of huge herbivores. So, allows for evolution of giant Sauropods, Stegosaurus, etc

Synapomorphies of Archosaurs:

1. Socketed teeth allow them to chew harder materials 2. Antorbital and mandibular fenestrae openings in front of the eyes and in the jaw respectively 3. Fourth trochanter: • a prominent ridge on the femur for muscle attachment • makes it easier to have an erect posture

Transition from Pelycosaurs to Therapsids

1. TEETH Pelycosaurs: teeth have largely identical shape - Homodonty Therapsids: multiple types (incisors, canines, molars) - Heterodonty Importance: • differentiated teeth associated with mastication (chewing) • facilitates digestion and increase rate of nutrient absorption • plays role in development of endothermy - why? 2. JAW Pelycosaurs: lower jaw fairly simple, acts as a lever Therapsids: flange for muscle attachment, shorter heads, and larger hole in lower jaw - all associated with increased chewing behavior • Lower jaw has reflected lamina, evolves into the malleus • Reptiles: middle ear has 1 bone = stapes • Mammals have 3 middle ear bones: incus (derived from skull bone), malleus (derived from jaw bone), stapes which allow for better sense of hearing 3. SKIN and HAIR: Pelycosaurs: • No evidence of hair • Potential use of large dorsal sail to regulate body heat instead Therapsids: • No sail • Evidence of hair based on infraorbital pits on the face and ridges in some lower Triassic cynodonts - initial purpose? Hypothesis: associated with the presence of a sensory function and only later a hairy, insulative covering over much of the rest of the body. • Suggests higher metabolism relying on production of internal heat = endothermy 4. BONY SECONDARY PALATE Pelycosaurs: No bony secondary palate Therapsids: some derived cynodonts have a complete seconday palate between mouth and nose that allows for the separation of the nasal and oral cavity Importance: • Allows the ability to breath and eat at once • Reinforces the skull • Can develop nasal turbinates • Reminder - warms air before gets into lungs and thought to be required for the development of endothermy 5. Lumbar ribs Early Pelycosaurs: Retain lumbar ribs Therapsids: Trend of reduced lumbar ribs and eventually complete loss Importance: • Suggests presence of muscular diaphragm • Associated with higher respiration rate and more active metabolism

The Origin of Flight

1. Top-down (= arboreal theory): • small, tree-climbing ancestor jumped branch to branch • wings were used in gliding (e.g., gliding lizards/squirrels) • weak flapping transitionally gives rise to full flapping 2. Bottom-up (= terrestrial theory): • bipedal, terrestrial, running predators flapping wings aid lift/balance (for leaping) and lighten load • similar to chickens flapping wings Variations on the terrestrial theory theme: a. Wings evolved as insect-snaring traps: • Archaeopteryx forelimb digits have well-developed claws b. Wing-assisted Incline Running Theory: • Extant birds use wings to climb up steep slopes • Wings initially used to increase climbing ability?

Exctinction events that give rise to mammals:

1. Triassic-Jurassic Extinction (T/J) • Extinction of many of the archosaurs and non-cynodont therapsids • Non-avian dinosaurs, crocodilians, and cynodont therapsids make it through 2. Cretaceous-Tertiary Extinction (K/T) • All remaining archosaurs go extinct except birds and crocodilians • Mammals make it through fairly unscathed The K-T extinction Problem # 1: Survival largely related to body size (exception: some large crocodiles and turtles survived): • > 10 kg = you die • < 10 kg = you live Problem # 2: Many amphibians (highly sensitive to environmental changes) did survive

So, why do we think birds evolved from dinosaurs?

20 synapomorphies that link Dinosaurs and Birds 1) Pubis (one of the three bones making up the vertebrate pelvis) shifted from an anterior to a more posterior orientation and bearing a small distal "boot". 2) Elongated arms and forelimbs and clawed manus (hands). 3) Large orbits (eye openings in the skull). 4) Flexible wrist with a semi-lunate carpal (wrist bone). - leads to the evolution of wing stroke 5) Hollow, thin-walled bones. 6) 3-fingered opposable grasping manus (hand), 4-toed pes (foot); but supported by 3 main toes. 7) Reduced, posteriorly stiffened tail. 8) Elongated metatarsals (bones of the feet between the ankle and toes). 9) S-shaped curved neck. - Unique to both 10) Erect, digitgrade (ankle held well off the ground) stance with feet postitioned directly below the body. 11) Similar eggshell microstructure. 12) Teeth with a constriction between the root and the crown. 13) Functional basis for wing power stroke present in arms and pectoral girdle (during motion, the arms were swung down and forward, then up and backwards, describing a "figure-eight" when viewed laterally). 14) Expanded pneumatic sinuses in the skull. 15) Five or more vertebrae incorporated into the sacrum (hip). 16) Straplike scapula (shoulder blade). 17) Clavicles (collarbone) fused to form a furcula (wishbone). - unique to both 18) Hingelike ankle joint, with movement mostly restricted to the fore-aft plane. 19) Secondary bony palate (nostrils open posteriorly in throat). 20) Feathers - unique to both

Dinosauria Synapomorphies

All bone features: • Ectopterygoid overlaps the pterygoid • Quadrate head exposed laterally • Posttemporal fenestra reduced to foramen • Epipophyses on anterior neck vertebrae • Deltopectoral crest >34% of humerus length • Antitrochanter on ilium prominent • Brevis fossa on the ilium • Perforate acetabulum • Obturator process short, restricted to proximal third of ischium • Femoral head rectangular/greater trochanter angular • Acending process of astraglus inserts beneath tibia • Calcaneum with flat surface for articulation of fibula • Distal tarsal 4 depressed and triangular

Marsupial Families

Ameridelphia • One North American species • ~80 South American species Australidelphia • Found in Australia and New Guinea • Great variety of sizes, shapes habitats, feeding styles

More locomotor adaptations

Anisodactyl foot (songbirds) hopping on ground Zygodactyly (woodpeckers, parrots) climbing vertically Syndactyl (kingfishers, hornbills) Didactyl (ostrich) two toes for running

Late Triassic

Appearance of • First mammals (small, insectivorous) • Turtles • Crocodiles • Marine reptiles • Flying reptiles • Dinosaurs (small, carnivorous)

What problems does large size create?

As animals get big, their weight increases dramatically. Stress, the pressure on the legs, increases with volume Strength, the stress required to break an object (e.g., a leg). Strength depends on cross-sectional area of the objects resisting stress. Varies to the square of length Strength = Combined Cross sectional area of 4 legs Stress (cubic) increases much faster than Strength (squared) if shape is constant. If size increases without a change in shape, stress on legs will quickly outpace strength due to the 2/3 power relationship.

Compare and contrast the types of flight from the Birds in Flight series of videos.

As you may have noticed from the videos, there are very distinct methods of flights depending on the morphology and behavior of the birds. The gull is able to raise itself out of the water and begins to run as it flaps its wings to generate lift off the ground and propel it into the air. The dove essentially takes off the ground vertically by using flapping flight and has a step angle of ascent. The mute swan is one of the heaviest birds and you can see how awkward it is for it to take off and how much power it has to generate to be able to actually fly. In the flight videos, you can see how graceful some of the birds are. The eagle is able to quickly maneuver and dive in the air to compete with other conspecifics. The albatross on the other hand is a classic example of a glider and floats on the air currents to move up and down only flapping occasionally. The tern on the other hand flaps constantly to fly very quickly and dart around the water's edge. The hummingbird has to flap extremely quickly to maintain hovering flight and is the only bird that is able to fly backward. You can see the unique wing motion it utilizes to remain in place.

The Cenozoic Era

Cenozoic Era: • biogeography and mammal diversification Cenozoic mammalian lineages: • Allotheria = multituberculates (rodent-like) • Prototheria = monotremes • Theria = marsupials + placentals

Eutheria/Placentals: Includes all the remaining mammals ~ 3500 extant species

Characteristics • Absence of epipubic bones that project forward from the pubic bones 1) support the pouch in marsupials 2) in both marsupials and monotremes they stiffen the torso during locomotion and limit hind limb movement during running • Presence of true patella • Changes in skull features • Changes in dentition • Corpus callosum linking two cerebral hemispheres

Metatheria/Marsupials

Characteristics • Defined by pouch in which female carries young • Development of young very unique 1) born at an early developmental stage 2) crawls into pouch 3) attaches to nipple 4) continues to develop for several months • Wide distribution • Australia, New Guinea, South America and one species in North America

Mammalian Variation in Reproduction

Common features of Mammals: 1) Lactation Common features of Therians: 1) Vivipary 2) Pregnancy

Reproduction in Therian Mammals

Common features: 1) Lactation 2) Vivipary 3) Pregnancy 3 Major components • endometrium = glandular lining of uterus, secretes materials that nourish the developing embryo • trophoblast = embryonic tissue that forms part of the placenta - external layer of early embryo (blastocyst) - develops into the placenta - forms tight association with endometrium • corpus luteum = ovarian tissue that secretes hormones (progesterone, estrogens) that are critical to maintenance of pregnancy Endometrium of the placenta: • internal lining of the uterus • site of embryo implantation • site of exchange with developing embryo

Bird migration: Why did it evolve?

Costs: • Energetically expensive: Must fatten up beforehand • Risky: • Can get lost • Can starve/run out of fuel • Critical timing • Predation (migrate at night) • Catastrophic weather events • Potentially high mortality Outweighed by benefits: • Avoid low winter temperatures at high latitudes • Take advantages of new resources on wintering grounds

Middle Triassic

Decline of Therapsids Diversification of Archosaurs • Mostly herbivores relatively small • goat to rhinoceros sized • Browsed close to the ground

End of Pleistocene extinctions

End of Pleistocene: • ~30% of mammalian genera become extinct • Includes for the most part large mammals • Also includes large birds: Moa (New Zealand), Elephant Bird (Madagascar End of Pleistocene extinctions: WHY? 1. Related to expansion & hunting by humans and/or.... 2. Related to climate changes - alternating period of glacial/interglacials

Allotheria

Evolutionary History • Appeared during the Jurassic • Most common Mesozoic mammals (200+ species) • Extinct during mid-Cenozoic Characteristics • Multicusped lower molars - multituberculates • Used for grinding, not shearing food • Narrow pelvis: potentially indicates they gave birth to poorly developed young, similar to modern marsupials Two lifestyles • Arboreal lifestyle - squirrel-like with a prehensile tail • Terrestrial - groundhog like with associated burrowing

Tyrannosaurs

Evolutionary trends • Increased body size • Increased size of head, but lighter skull • Shorter forelimbs • Reduction of forelimb digit number • Coprolites provide evidence they chewed food Similarities between T. rex and modern birds? • Sequence amino acids of T. rex collagen fragments (68 mya!!) • Compare sequence with that of extant animals • Highest similarity with chicken sequence.

Maniraptora

Evolutionary trends • Relatively small size • All advanced forms have feathers • Arm structure similar to that seen in modern birds • Hands have three digits • Include ancestral forms and.... modern birds!

Origin of Mammals

First appear during Paleozoic (Carboniferous) • Primitive synapsids = Pelycosaurs, e.g., Archeothyris Late Paleozoic (Carboniferous and early Permian): • Early synapsids become main terrestrial vertebrates • Most Pelycosaurs go extinct during Permian • Therapsids appear (Permian) Mesozoic: Archosaurs dominate terrestrial ecosystems • But most eventually become extinct at the K-T boundary • Therapsids present, but most small and definitely overshadowed Cenozoic: Modern mammals evolve and then become dominant Two successful periods for synapsids: - Permian (pelycosaurs, early therapsids) - Cenozoic: All modern mammals 5,400+ known species including humans

Transition from cynodonts to mammals

Four main differences between cynodonts and mammals: a) Body covered completely in fur b) Enlarged brain structure c) Tooth structure and function d) Lactation • Fur: Sensation, related to endothermy • Brain Size Increase: Associated with all the nerves running from the fur and increased olfactory capabilities • Tooth Structure: Increased heterodont dentition associated with endothermy; leads to a diphyodont condition - two sets of teeth (milk and adult) • Suckling and lactation: Requires dissociation of breathing from swallowing and presence of secondary palate

Breakup of the Pangaea: Jurassic and Cretaceous

Jurassic and Cretaceous: • Formation of Laurasia - modern N. America and Gondwana modern S. hemisphere land masses • Formation of Atlantic Ocean • Separation of Australia/New Zealand/New Guinea • India still close to Africa

Digestive adaptations vary with food type

Lack teeth, so food stored in crop (enlarged part of esophagus) • easy means of regurgitating to offspring Stomach enzymatically and physically digests • proventriculus (chemical) and gizzard (grinds, with stones = gastroliths) Birds with varying seasonal diets change in gut morphology • starlings enlarge intestines in fall when they shift to plant diet

How fast did dinosaurs grow?

Lines of arrested growth - just like trees every year there is seasonal growth

Reproduction in Monotremes

Main characteristics: • lay eggs • young hatch at embryonic stage • long period of parental care • platypus: 16 weeks

How do we weigh dinosaurs?

Method #1 There is a regular relationship between the weight of an animal and the cross-sectional area of its legs. This relationship has been developed for modern animals, using animals that range in size from shrews to elephants. In general: Mass is proportional to Leg area^2.75 Weights derived in metric tons (=1000 kilograms): • Big Theropods (e.g., Allosaurus, Tyrannosaurus): 2 - 7 tons • Sauropods (e.g., Diplodocus, Apatosaurus, etc.): 6 - 50 tons, biggest ~180 tons • Ornithopods (e.g., Iguanodon): ~5 tons • Stegosaurs: 2 - 3 tons • Big Ceratopsians (e.g., Triceratops): 4 - 6 tons Method #2: Scale models Paleontologists make a reduced scale model of a dinosaur with known ratio to the actual size, estimating muscle mass, skin morphology, etc. They then use Archimede's principle to estimate the volume of the model They scale this up based on the ratio (e.g. 1:40) and multiply by the average density of living archosaurs ~.9kg/liter Method #3: Same concept, but uses modern lasers to estimate skeletal volume instead and then uses 3-D digital analysis to recreated dinosaur body plan

Cenozoic: New types of mammals

New ecosystems lead to new opportunities for diversification of mammals • Appearance of horses, antelopes, elephants + predators: large cats and dogs Pangaea is broken up and the land masses are then separated • Accelerates evolution of different faunas, e.g., in N. and S. America, Europe, and Australia all have very different mammals today Separation of Old World (South America, Africa, Australia) and New World (North America, Europe, Asia)

Avian hearing: Owls

Owls can find prey in complete darkness based on sound Face and skull asymmetric • sounds reach at slightly different times • makes it easier to pinpoint exact source of sound Sound Localization • Azimuth (horizontal plane) - Coincident detectors - Sound delay between ears codes for horizontal placement (summation) Asymmetry in directional sensitivity: Right ear points up Left ear points down Compares intensity in the two ears to determine location of prey without needing to see

Pleistocene: Ice Ages

Pleistocene: 2.5 mya - 12,000 years ago. Characteristics: • First required formation of ice caps • Four main ice age episodes • Last ice age ~10,000 years ago: currently in an interglacial episode • Up to 30 % of land masses covered with ice Associated with special ecosystems: • Mammoth Steppe - mammals including mammoth, lions, woolly rhinoceros

Sauropods

Quadrupedal giants • even compared to other dinosaurs • Body form similar to hippos and elephants - deep rib cages, columnar limbs, long metacarpals, short toes • Elongated necks with small heads, adapted for cropping leaves • Gastroliths found associated with skeletons • Some evidence they moved in herds • Phylogeny still poorly understood Diplodocids • fed on low vegetation, but could use tripodal stance to defend themselves Brachiosaurs • could reach necks up to feed and browse on higher vegetation • Amphicoelias - 122 tons, 60 m long (largest vertebrate to walk the planet) • One vertebrae is 8 ft long and 7 ft wide and there are 17 in the neck!

Detection of Infrasounds

Some birds can detect sounds of lower frequencies than humans Why could this be useful? Low frequency sounds (infrasounds) produced by surf along ocean shores, thunderstorms, waterfalls, volcanoes, etc... Infrasound propagates over long distances with little attenuation Birds can detect approaching thunderstorms etc.... from long distance? Hypothesis: Use this information for orientation during migration?

Ornithischia species

Stegosaurs - paired rows of plates and spikes on the tail Ankylosaurs - "tanks" that possessed body armor Ornithopods - duck billed and bipedal Pachycephalosaurs - "bone- heads" with solid bone domes on skulls Ceratopsians - frill of bone on the skull and a prominent beak

What made it through the P/T extinction?

THERAPSIDS • Mammal-like reptile synapsids • Herbivorous dicynodonts • e.g. Lystrosaurus - dominant form • Carnivorous cynodonts • Ancestral to mammals ARCHOSAURS • Diapsid reptiles that are ancestral to dinosaurs and crocodylians • Herbivorous and carnivorous forms

Explain this statement. The K/T and Pleistocene extinctions have driven the evolution of modern mammalian diversity.

The Cretaceous-Tertiary extinction wiped out the non-avian dinosaurs. This allowed the mammals who had been the less dominant group to diversify in thrive in the post extinction ecological rebound. This is why the Cenozoic Era has classically been called the 'Age of Mammals'. The lack of apex predators allowed mammals to fill several new ecological niches. The Pleistocene extinctions that were associated with alternating glacial and interglacial cycles placed a selective pressure on the mammals living at those times. This pushed mammals to larger body sizes and increased fur investment to be able to survive these climates in the northern latitudes. This had an effect on hominid populations as well. Together the K/T and Pleistocene extinctions have established the current mammalian fauna that exists today.

Avian Olfaction

The case of the tangerine-scented Crested Auklet: Crested Auklet "ruff sniff" during courtship Feathers smell like tangerine = social signaling function Seabirds: Birds are attracted by krill-scented slick on water, not by control slick Turkey Vulture: • Scavenger • Food located by smell from the air • Ethanethiol = the "smelliest substance" in existence (Guinness record book)

Compare and contrast ornithischian and saurischian dinosaurs.

The main morphological difference between Ornithischian and Saurischian dinosaurs is the orientation of the hip with the Ornithischia being "bird hipped" and the Saurischia being "lizard-hipped". Other features that are unique to the Ornithischians are their leaf shaped cheek teeth, the presence of cheeks, a lowered jaw joint for occlusion and a predentary bone that supports a beak. All of these traits are due to the fact that Ornithischians are herbivorous. The Saurischians on the other hand had elongate hands, increased neck articulation surfaces, and new adaptations in their hand structures. There are two main clades - the giant herbivorous sauropods and the carnivorous theropods that give rise to birds.

Compare and contrast the Pelycosaur clade to the Therapsid clade.

The transition from pelycosaurs to therapsids is one of the first steps in mammalian evolutions and was accompanied by a series of morphological changes. Pelycosaurs were homodonts meaning they had identical tooth shapes, while the therapids were heterdont meaning they can process different types of food more efficiently. Pelycosaurs had fairly simple lever style jaws, while the therapsids had more area for muscle attachment to allow for chewing their food to increase nutrient intake. Pelycosaurs were most likely endotherms and had no hair, while therapsids begin to display characteristics of endothermy including the presence of hair. Pelycosaurs have no bony secondary palate, while therapsids have a secondary palate between the mouth and nose which allows for the animal to breathe and eat as the same time. Lastly, pelycosaurs retain lumbar ribs, while therapsids have lost them suggesting that therapsids may have had a diaphragm for increased respiration. All of the evolutionary changes point to therapsids having increased metabolic rates, being more active, and moving towards a truly endothermic lifestyle as compared to pelycosaurs.

Why do we think birds evolved from dinosaurs?

Theropoda: Coelurosaurauria • Bipedal • Most carnivorous • Most lineages include species with feathers • Three groups - which shares the most recent common ancestor with birds? • Tyrannosaurs • Ornithomimosaurs • Maniraptors

Mammalian Lineages

Three Clades: • Allotheria - multituberculates (extinct) • Prototheria - monotremes • Theria • Metatheria - marsupials • Eutheria - placentals

Bird Flight: Types of Flight

Three main types: A. Gliding flight: simplest form of flight • Relies primarily on balance of lift and gravity (weight) • Birds often relies on thermals to climb up, then glide down, etc B. Flapping flight • Energetically expensive as it requires large breast muscles C. Hovering Flight • i.e Hummingbirds

The Great American Biotic Interchange

To N. America: • Extant porcupines (rodent), armadillos (edentate) & opossums (marsupials) • Extinct ground sloths and glyptodonts (both edentates) did colonize as far north as the USA To S. America: • 17 families in all: rabbits, mice, foxes, bears, raccoons, weasels, cats, peccaries & deer still have close living relatives in N. America • Extant tapirs & camels are still alive in S. America but they went extinct in N. America • Mastodons & horses went extinct on both continents (horses were re-introduced from the Old World in historical times) Hypothesis: • Northwardly migrating animals often were not able to compete for resources as well as the North American species already occupying the same ecological niches; those that succeeded in becoming established were not able to diversify much. • Southwardly migrating Nearctic species established themselves in larger numbers and diversified considerably more, and are thought to have caused the extinction of a large proportion of the South American fauna. • In fact, about half of all species of today's South American mammal fauna derives from this influx of northerners.

Evolution of Early Birds and Extant birds

Two independent radiations during Mesozoic: A. Enantiornithines: • Generally retained teeth and clawed fingers (same as Archeopteryx) • Dominant birds of the Cretaceous • All extinct at the end of Cretaceous • Radiated into various forms, e.g., Enantiornis, Sinornis, Gobipteryx B. Ornithurines: All extinct; various aquatic & terrestrial forms • E.g. Hesperornis, Ichthyornis Leads to the evolution of AVES = NEORNITHES • All modern birds broke into Paleognathae and Neognathae • Evolved during late Cretaceous/early Cenozoic

Bird Flight: Wing Loading

Wing loading = body mass/wing area • Greatly varies among species • Low wing loading = less power needed to take off and stay in the air

Sensory perception

a) Vision - large eyes, optic lobes, and midbrain - locate prey + avoid being eaten - see UV light (feather color + food) b) Olfaction - some with very small olfactory bulbs (poor smell) - water, ground, and hunting birds have larger bulbs (find food or escape predation) - may play a role in navigation (homing) - tangerine scent of crested auklets is used in mating c) Hearing - roughly equal to human range - large tympanic membrane to enhance sensitivity - esp. sensitive in owls (nocturnal hunters) - facial ruff is parabolic sound reflector - songbirds tuned to high frequency (song) as well - some tuned to low freq. too (approaching thunder) d) Other - air pressure (flight, weather patterns) - magnetic fields (orientation; magnetite found in heads of pigeons)

Which of the following statements is correct? a. Dinosauria is a monophyleic group that contains Aves. b. Aves is a monophyletic group that contains Dinosauria. c. Archosauria is a paraphyletic group that contains Crocodylia. d. Archosauria is more closely related to Synapsida than it is to Lepidosauria. e. 1 and 3 f. 2 and 3 g. 1 and 4 h. 2 and 4

a. Dinosauria is a monophyleic group that contains Aves

Which of these is not a feature of herbivorous non-avian dinosaurs? a. Enlarged pelvic muscles and a symmetrical foot to support their bulk b. Leaf shaped teeth to provide a continuous cutting surface c. Cheeks that allow for processing food in the mouth d. Occlusion of the jaw joint that allows teeth to engage food at the same time e. Predentary bone for attachment of a beak

a. Enlarged pelvic muscles and a symmetrical foot to support their bulk

There are seven vertebrae in a human's neck, how many vertebrae do you think are in a giraffe's neck? a. 1 b. 7 c. 14 d. 21 e. 28

b. 7

True or False: The Triassic was warmer and more humid than the Permian. a. True b. False

b. False

Which of the following is correct in regards to Archaeopteryx? a. It had all of the characteristics of modern birds. b. It had different types of feathers indicating it could have flown. c. It had no teeth and a beak like structure for feeding. d. It had a bony operculum and a feather covered flap. e. It evolved in the Permian.

b. It had different types of feathers indicating it could have flown.

One of the major innovation in Archosaur morphology and a defining synapomorphy is the possession of: a. feathers. b. a furcula. c. a fourth trochanter. d. a unique bird hip structure. e. a unique jaw joint occlusion.

c. a fourth trochanter.

The Wing Assisted Incline Running (WAIR) theory of flight evolution hypothesizes that: a. birds became arboreal and used their wings to glide down to the ground. b. birds used their wings to assist them in locomotion on the ground for leaping. c. birds used their wings for increased agility while climbing up trees. d. birds used their wings for catching fish while flying. e. flight originated in Tyrannosaurid dinosaurs.

c. birds used their wings for increased agility while climbing up trees.

Based on our current understanding of dinosaur/bird phylogeny, if you could compare modern bird DNA to the DNA of Mesozoic animals, you would find the greatest similarity with: a. Pterosaurs b. Ornithischia c. Sauropods d. Theropods e. Crurotarsi

d. Theropods

Which of these is not seen in birds? a. Nesting behavior b. Vocalization c. Social Feather Displays d. Viviparous reproduction e. Keratinous scales

d. Viviparous reproduction

Which of the following have been hypothesized to be used by birds for long distance migration? a. The sun b. Magnetic fields c. Sense of smell d. Infrasounds e. All of the above have been hypothesized

e. All of the above have been hypothesized

Which of these mammal synapomorphies do blue whales not have? a. Hair b. Lactation c. Diaphragm d. Adipose Tissue e. They have all of the above

e. They have all of the above

Permian-Triassic extinction

• 57 % marine invertebrate families • 95 % all marine species • 49 % tetrapods • 70% of all terrestrial species Most life on Earth is eliminated!

How do we know about cardiovascular systems of dinosaurs?

• 600 mmHg • Only can be done with a four chambered heart - seen in birds and crocs • Thick walled arteries and capillaries • Without these dinosaurs would not have been able to live

Dinosaurs were Airheads

• Allowed for easier support of skull on a long neck • Increased musculature for prey capture • Overall lightening of load is advantageous

Derived Synapsids: The Therapsids

• Appear during Permian • Become dominant form during second half of Permian and an important component of fauna until early Cretaceous • Include herbivorous forms and carnivorous forms • Most disappear during Mesozoic except Cynodonts that transition into modern mammals, and then become dominant terrestrial vertebrates during Cenozoic • More derived than Pelycosaurs • Mainly S. hemisphere (Gondwana)

Avian vision

• Birds are highly visual animals • Brain has large optic lobes and midbrain • Large eyes to locate prey and avoid being eaten • Eyes set on the sides of the head What is the implication of eyes on the side of the head? •In many species, only monocular vision (duck) •But... • Some have good binocular vision (owls) • some species are intermediary (bittern heron) What wavelengths do animals see? Some birds can see in ultraviolet light • Better prey detection • Used for orientation during migration

Early Synapsids:The Pelycosaurs

• Carnivorous or herbivorous • Some have a sail (Pelycosaurs = "sailbacks"): • contains blood vessels; not sexually dimorphic • possibly used to regulate body temperature • Ectotherms • No hair • Include ancestors of mammals • Most primitive Synapsids • Mainly N. Hemisphere (Laurasia)

Ornithischia were Herbivores

• Complicated to be a strict herbivore • No multicellular animal can produce enzymes capable of digesting cellulose that forms the cell walls of plants • Special feeding apparatus - heavy muscles and suitable jaws and teeth that can mechanically breakdown plants • But there is still a lot of energy stored in cellulose so most herbivores develop a symbiotic relationship with Archaea or Bacteria that are able to produce cellulose-digesting enzymes • They maintain these symbiotes in special pockets in their digestive tract (over 40% of your digestive tract is filled with bacteria!) • No ornithisican ever reverted back to a carnivorous diet because modifications involved in dedication to plant processing precluded such a shift in diet So, their traits all focus on this lifestyle • Leaf shaped teeth to provide a continuous cutting surface • Cheeks allow for containing the bolus inside the mouth to continue processing • Occlusion of the jaw joint allows teeth to engage food simultaneously for chewing, instead of slicing • Predentary bone for beak attachment allows for cropping of leaves off of trees

What caused these climate changes?

• Decrease in atmospheric CO2 = "reverse greenhouse effect" • Continental drifts: continental masses reach high latitudes • Leads to the formation of ice caps: • Antarctica: End of Eocene • Arctic: ~30 million years later = end of Miocene Importance: • Water locked in ice • Decrease in seawater levels • Closes the Isthmus of Panama • Interrupts water circulation • Water circulation around the Earth interrupted • Related to formation of Gulf Stream • Brings warm water from tropics to Western Europe

What makes it through the Triassic/Jurassic extinction?

• Dinosaurs start to dominate the large vertebrate fauna • Marine and aerial diapsids have a massive radiation • Mammals are small insectivores/omnivores at this time Archosaurs • Include dinosaurs, crocodilians, birds, pterosaurs • All extinct by the end of Mesozoic except crocodilians and birds (and maybe turtles)

How does a meteor impact in one part of the world lead to a global extinction?

• Dust cloud that blocks photosynthesis for a year or less • Sulfuric aerosols decreasing global temperature and reduced sunlight by 10-20% • Intense pulse of infrared radiation • Large tsunamis associated with an oceanic impact • Small animals that don't rely on large food sources can survive, while large animals die Alternative Hypotheses • Deccan Traps - flood basalt over an 800,000 year period • Sea Level Regression - the drop at the end of the Cretaceous affected continental shelf area • Widespread fungal or viral disease • Evidence of a long term decline before the mass extinction

Reproduction in Placentals

• Highly developed placenta • connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply • The young develop in uterus for relatively long time before birth • A whopping 22 months in elephants! At birth: 1. Altricial: pattern of growth and development in organisms which are incapable of moving around on their own when born i.e. rat, human; presumed to be primitive condition 2. Precocial: young are relatively mature and mobile from the moment of birth or hatching i.e. many herbivores

Wings in Palaeognathae (Ratites) "flightless birds"

• Hold their wings out to help them balance when they run, especially if they suddenly change direction. • Used for displays and courtship, along with the tail feathers.

Thermoregulatory Strategies

• Homeothermic • Endothermy (Tachymetabolic) • Mass Homeothermy (Bradymetabolic) • Heterothermy • Ectothermy • Intermediate

Prototheria

• Includes Platypus (Australia) and Echidnas (Australia and New Guinea) • Early divergence from other mammalian lines (~200 mya in the Jurassic) Monotremes - means single opening Why is that an appropriate name? • Reproductive, excretory, and defecatroy ducts all open into a single duct • Similar to in reptiles, but different from female placental mammals (vagina, urethra, anus) Characteristics • Lay eggs • Lactate to produce milk, but no nipples • milk fields that are excreted from an opening in the skin • Adults lack teeth • Reptile-like gait • legs on the side of the body, not underneath • Hind legs in platypus have a spur that contains venom • extremely rare in mammals

How to get large without breaking?

• Keep your legs straight. Most breaks occur during bending, not vertical loading. • Sauropods have knees that lock in place • Big living animals like elephants don't bend their legs much when walking.

Cenozoic: New ecosystems

• Later during Cenozoic (Oligocene to Miocene) • Formation of ice caps, Earth temperatures cool down, climates dry out • New ecosystems • tundra, boreal conifer forest, grasslands, and deserts

Changes in ecosystems during Cenozoic

• Mesozoic: large herbivorous dinosaurs (Sauropods) browse vegetation • Prevents the formation of large expanses of forest, similar to modern elephants maintaining savannas • Early Cenozoic: large tropical forests even at high latitudes • Modern Canadian Arctic regions had turtles and crocodiles

Two major clades: Ornithischia and Saurischia

• Ornithischia ("bird-hipped") • Leaf shaped cheek teeth, cheeks, lowered jaw joint for occlusion, predentary bone that supports a beak • Saurischia ("lizard-hipped") • Elongate hand, expansion of the neck and neck articulations, adaptations in hand structure

Early Triassic

• Pangaea begins to break up • Transition from a relatively moist & mild worldwide climate to a more stratified arid climate worldwide • Warm moist regions at the poles and more arid climates at the equator • No polar ice caps and forests extended to the polar regions

Theropods

• Raptorial hands with large sharp claws and kinetic jaws for swallowing large prey • Enlarged pelvic muscles and a symmetrical foot allow for a bipedal, cursorial lifestyle Ceratosaurs - dominant late Triassic/early Jurassic carnivores Tetanurans - stiff tailed with unique teeth and horizontal wrist motion Coelurosaurs - first feathered dinosaurs Maniraptors - flight stroke, hand changes

Archaeopteryx

• Raven size • Not quite a bird yet! • Late Jurassic, no descendant • Mosaic of modern bird + dinosaur characters (bony tail, teeth, front legs w. claws) • Different types of feathers • Able to fly

Saurischians

• Sauropods - the second great radiation of plant eating dinosaurs • the true giants among the dinosaurs (large size) • small head, tall coarsely serrated teeth, long neck, thick limbs with tibia > femur, thumb with heavy claw • Theropods • carnivores with 3 fingered hands • jaw kinesis, enlarge pelvic muscles and symmetrical feet

Early Eocene landscape (~50 MYA)

• Still "Hot House World" • No ice caps at poles • Variety of mammals & birds • Early primates • Luxuriant vegetation: palm trees, tree ferns, cycads, magnolias, etc. • Forests found even at high latitudes, above Arctic Circle

Bird Migration: Orientation and Navigation

• Sun's position in the sky (use with internal clock to determine direction and time of day) • Polarized and ultraviolet pattern of sky light • Earth magnetic field (use to determine latitude) • Infrasounds • Star patterns (nocturnal migrants) • Short distances - olfactory cues • Multiple mechanisms can be used with a lot of redundancy

What are issues with the evolution of large size?

• Support • Food availability • Cardiovascular/Respiratory System • Thermoregulation • Locomotion • Others

Amniote differentiation Two lineages separated very early (mid-Carboniferous, ~320 MYA)

• Synapsids include: Pelycosaurs Therapsids Mammals • Sauropsids include: Non-avian dinosaurs Turtles Lepidosaurs Crocodylians Birds

What was the selective pressure for the evolution of feathers?

• Thermoregulation? But...bird ancestors lacked turbinate bones in nose, so maybe not endothermic And why feathers and not hair (much more simple, widespread, easier to replace)? • Social display? • Keep eggs warm at night? • Assist with flight? But...what about bats, pterosaurs? And flightless bird ancestors had feathers

Endothermy vs. Ectothermy

• This argument has been going on for a hundred years, and will continue for another hundred • Most likely endothermy evolved sometime along the dinosaur lineage, but it is unclear exactly when • What can birds tell us?

Adaptations of feathers

• Tracts of dead keratinized tissue • homologous with lepidosaur scales • All have calamus, rachis, and vane containing barbs and barbules • Different types • flight and tail feathers long and asymmetric for optimizing air displacement • downy feathers for insulation

Early Triassic: Vegetation

• Vegetation dominated by gymnosperms: • Conifers • Ginkgo • Cycads • Tree ferns • Horsetails • No Angiosperms (= flowering, seed-producing plants): appear during Cretaceous • No grasses: appear during the Cretaceous ' Oxygen levels at roughly ~14%... the lowest concentration in 500 million years, thus leading to novel adaptations.

Reproduction in Marsupials

• Viviparous • Corpus luteum not maintained during pregnancy • poorly developed placenta • young born at early stage of development • At birth, young ejected directly into pouch (some species) or... crawls into pouch (well developed forelimbs) • Then, spends considerable amount of time attached to nipple in pouch

Advantages of Altricial Birth?

• Young altricial mammals are essentially ectothermal • Depend on parents for food and warmth • don't have to spend own energy producing heat • can allocate more energy on growth • Parental care ensures successful development