Geo 100 Dinosaurs Final
Know the ages of Archaeopteryx and where it was found and its significance to evolution (shortly after the evolution was proposed).
-Origination of features: Most of the characteristics we think of as being diagnostic of birds were inherited from dinosaurian ancestors. These include: wings, feathers, air-filled bones connected to lungs, wishbone (furcula), and three functional toes. Confuciusornis (another related bird) The earliest bird (Early Cretaceous ~ 125 Ma) with a beak (no teeth) Retains large claws on hands (like Archaeopteryx) Pigment cells on feathers = grey/red-brown/black Fish found in throat of one specimen Epidexipteryx hui, Jurassic of China; phylogeny: not a bird, but a theropod close to dinosaurs. There were no flight-related (contour) feathers. Age: Middle or Late Jurassic. Size: ~pigeon. Significance: Its old age and specialized feathers
Dinosaurs that dominated each epochs of the Mesozoic
-Triassic: Some small dinosaurs but mainly dominated by reptiles and amphibians (crocidilamorphs) -Jurassic: Dinosaurs dominated this epoch. Most notably the very large herbivorous Sauropods, large Stegosaurids, Hypsilophodontids, and Allosaurids -Cretaceous: Dominated mostly by hadrosaurs, certopsians, anklyosaurs, coelurosaurs, and turannosaurids
Most of the features that are thought of as avian originated in theropod dinosaurs before flight and birds. Know what these features are and how they set the stage for flight.
-What makes a bird a bird: Feathers, Furcula (wish-bone), unidirectional lung, pneumatic bones, wings, fused vertebrate, fused hand bones, short tail-fused caudals, no teeth, warm-blooded, reversed first toe
Know the meaning of altricial and precocial and how dinosaurs are assigned to one or the other groups.
Altricial = requiring nourishment Mammals, some birds (hawks, passerines, etc.) Require food and care Essentially immobile at birth Ends of bones made of soft cartilage - cannot bear weight Precocial = Gets it's own nourishment Able to defend themselves at hatching and require less food and help (most reptiles, ducks, turkeys, etc.) Relatively mobile at birth. Ends of bones ossified (hardened bone) - can bear weight *Some evidence of theropods that show altricial (taking care of babies at nest) and some sauropods are precocial.
Know what major groups were affected - or was dinosaurian the only clade to suffer?
Ammonoid, clams and snails, rudists, inoceramids, mosasaurs , plesiosaurs, foraminifera, pterosaurs, dinosaurs, mammals, some plants
Changes in the dinosaurian faunas at around the same time angiosperms appeared
Angiosperms began to make their appearance at the end of the early Cretaceous. The dinosaurian fauna at this time consisted of ankylosaurs and large ornithopods that dominated while sauropods and stegosaurs dwindled.
What are the major evidences that an impact occurred and are they found world-wide or only locally?
"The magic clay layer" Researched at Gubbio, Italy Found a whole lot of iridium in the clay - iridium comes from outer space Hypothesized that a big meteor impact would have left behind this concentrated iridium and the impact is what led to the extinction
What evidences led to the discovery of the impact site and where is it located? In terms of ecology, understand what changes may have caused or contributed to the end of Cretaceous extinction.
-In N. Italy, the clay layer that marks the end of the Cretaceous contains an unusually high abundance of iridium.
What was the nature of the feathers and where were they located in feathered theropods? Archaeopteryx has long been considered the oldest known bird, so why is that status now being questioned?
Archaeopteryx serves as a classic example of a missing link between "reptiles" and "birds". Identified as a bird, only because it had feathers. Otherwise it would be classified as a theropod dinosaur. Contraction of Tail -Archaeopteryx is more angular -Modern bird is rounded Four Wings Hind leg wings have been reported in Archaeopteryx and one Early Cretaceous bird...but having trouble knowing the norm. Problem: Search model (noone looked for feathers on hind legs for Archaeopteryx); Problems with preservation New study: reveals issue of hind wings and reports discovery on 11 early (basal) birds.
Understand the basic function of avian lungs and the evidences for similar lungs in certain groups of dinosaurs.
Birds have unidirectional lungs. ***
How do we know the ontogenetic age of dinosaurs?
Definition of ontogenetic age: the origination and development of an organism, usually from the time of fertilization of the egg to the organism's mature form - although the term can be used to refer to the study of the entirety of an organism's lifespan. Prof Britt said in class that this is kind of up for debate (think of that video about lizards in California that we saw) because it is hard to pinpoint exactly when a group has differentiated enough to be considered a new species
What is used to determine whether specific dinosaurs were nocturnal or diurnal?
The size of the eye ring in the skull or the eye itself Comparison of scleral rings of dinosaurs with those of modern animals provide first evidence of nocturnal dinosaurs Velociraptor & Microraptor - possibly nocturnal Psittacosaurus & Diplodocus - possible dawn/dusk Most taxa diurnal
New discoveries: How is it that paleontologists can determine that mononykids (Mononykus, Albertonykus, and other Alvarezsaurids) were probably ant-eaters?
The small and needle like skull helped eat ants like modern anteaters Claws was most likely to rip off bark on trees and dig They have long and slender legs, stumpy arms with huge claws and tweezer-like jaws Proportionately, the forelimbs are shorter than in a Tyrannosaurus but they are powerfully-built, so they seem to have served a purpose," Longrich said. "They are built for digging but too short to burrow, so we think they may have been used to rip open log in search of insects
New discoveries: Be able to explain the significance of the little Italian theropod Scipionyx in terms of preservation and ontogenetic age
The specimen was preserved in the marine Pietraroja limestone formation or Plattenkalk, well known for unusually well-conserved fossils There is only one fossil known of Scipionyx, discovered in 1981 by an amateur paleontologist and brought to the attention of science in 1993 The find generated much publicity because of the unique preservation of large areas of petrified soft tissue and internal organs such as muscles and intestines. The fossil shows many details of these, even the internal structure of some muscle and bone cells. Also it was the first dinosaur found in Italy. Because of the importance of the specimen it has been intensely studied. In the guts of the fossil some half-digested meals are still present, showing Scipionyx ate lizards and fish. Perhaps these had been fed to the young animal by its parents.
Dicotyledons and Monocotyledons
The two groups of which all flowering plants (angiosperms) were divided into. Dicotyledons have an embryo that bears two cotyledons (seed leaves). Monocotyledons have a single cotyledon. Parrellel veined and petals in groups of 3 rather than 5.
Know which groups were likely the most active and had high metabolic rates.
Theropods and ornithopods
Some claim that dinosaurs did not go extinct at the end of the Cretaceous, but lived on into the Paleocene. What evidences do they cite and what leads most paleontologists to reject such claims?
They are looking at reworked rock which makes it seem like the bones come from after the extinction
Understand the limitations of reproduction by spores.
They lack seeds or flowers, and require water for reproduction, efficiency of pollination
When did dinosaurs become the dominant terrestrial vertebrates
They were established as the dominant terrestrial vertebrates by the end of the Middle Jurassic.
Social behavior/herding
brooding is a trait of endotherms, some dinosaurs brood. Herding as well.
Be able to explain the relationship between body temperature strategies in extant animals and heart structure
chambered hearts are required to maintain high blood pressure. Since relatives of dinosaurs have 4 chambered hearts it stands to reason that dinos were endotherms. Four-chambered heart of birds & mammals allow adequate oxygen supply for endothermy. In mammals and birds oxygenated and deoxygenated blood is fully separated in the heart. In crocodilians also have a form of 4-chambered heart. In lower vertebrates there is a mixing (inefficient). **Mammals, birds, crocodiles (kind of) all had 4 chambers so dinosaurs probably had 4.
Be able to explain the relationship between body temperature strategies in extant animals and other behavior
dinosaurs lived in moderate temperatures but some lived far north where there were periods of prolonged darkness. This means temperatures dropped so Dinosaurs would need to maintain body temperature for metabolism to happen.
Be able to explain the relationship between body temperature strategies in extant animals and predator-prey ratios
endothermic predators need more prey to support fast metabolism. So the predator to prey ratio for endotherms is more prey required per endotherm than ectotherm. It seems that the predator to prey ratio of dinosaurs is more consistent with endotherms but this is hard to tell because not all fossils are found, so it may be an incomplete record.
Be able to explain the relationship between body temperature strategies in extant animals and blood pressure
endotherms have high blood pressure and ectotherms do not. Larger sauropods have a harder ability to give off heat and so possibly have different blood vessels.
Be able to explain the relationship between body temperature strategies in extant animals and bone mircrostructure
endotherms have many canals in the bones where blood vessels are housed in order to aid the rapid exchange of valuable materials needed throughout the body, ectotherms do not have the same network of blood vessels. Dino bones look more like the bones of the endotherms as it relates to blood vessel networks. Haversian bone, a type of bone riddled with blood vessels and sites of active remodeling were once cited as evidence of warm-bloodedness. That type of bone, however, is found in many classes of vertebrates - including modern cold-blooded forms.
The google doc has pictures and diagrams for
faunas and times for dinosaurs and clades, timeline for dinosaurs, underprint and overprint picture, and cladograms
New discoveries: Death pits:
highly localized areas of liquefaction caused by large-dinosaur (possibly sauropod) trampling of saturated sediments. High quality skeletal preservation suggests that most individuals were buried within days to months after their deaths. Carcasses were buried successively, coming to rest above previously buried individuals.
Be able to explain the relationship between body temperature strategies in extant animals and weight (mass)
large endotherms have problems with overheating, so large sauropods and other immense dinosaurs would have the same problem. Endothermy in large dinosaurs seems improbable.
Be able to explain the relationship between body temperature strategies in extant animals and metabolism
Endothermic have higher/faster metabolism than Exothermic. The rate of metabolism is indicative of their temperature.
Know and understand the following terms: endothermic, exothermic, poikiolothermic, homeothermic
Endothermic: "warm blooded" High metabolic rate essentially constant body temperature (homothermic) Internal heat source (term hot-blooded is an exaggerated phrase, use for dramatic impact) Temp fluctuation small (couple of degrees C) In general: birds, mammals Exothermic/Ectothermic: Low metabolic rate dramatic fluctuations in body temperature (heterothermic) external sources of heat (the sun, or objects heated by the sun) In general: invertebrates, fishes, amphibians, reptiles, professors Poikiolothermic: Fluctuating body temperature without severe symptoms (Ex. Large sea turtle) Homeothermic: Tightly regulated body temperature
What is the origin of the "human" footprints found primarily in Early Cretaceous rocks in Texas?
Erosional features that somewhat resembled human footprints, eroded bipedal dinosaur footprints, and some were just carved by modern day people trying to scam others.
How does plate tectonics impact evolution and extinction?
Evolution: creation of new environments, splitting up gene pool Extinction: volcanic activity can cause extinction *Can change the sea level which affects climate. Climate can cause extinction
Understand the function of gastroliths and be able to explain which dinosaurs have been found with these stones.
Gastroliths are stones that some animals will swallow to aid in digestion. When such stones are found in the abdominal region of a skeleton, they can be classified as gastroliths. Psittacosaurus, Caudipteryx have been found with gastroliths. So far all found with gastroliths are herbivores.
Periodically, non-bird dinosaurs younger than the end of the Cretaceous are reported - why then do nearly all paleontologists insist that non-avian dinosaurs went extinct at the end of the Cretaceous?
Geological events cause either for the fossils leaving the rock bed and ending up washed up with younger fossils, or uplifting geological events cause it to be lifted in the geological layer
Be able to explain the "ground up" and "tree down" hypotheses for the origin of flight in birds/dinosaurs and which theory is best supported by new feathered dinosaur findings.
Gliding (Travel from the tops of the trees back to the ground) Running (used to lift off of the ground Best theory:
How do paleontologists know the ontogenetic ages of dinosaurs and how we know that this method is reliable?
Growth rings in bones and the separtation between them Count the growth rings (L.A.G.s = lines of arrested growth) Dinosaurs seemed to have determinate growth Like mammals & birds, they have a maximum size (determinate growth) Based on LAGs closely spaced in large/old individuals Thus growth slowed with age
Be able to explain the primary differences between the reproductive strategies of gymnosperms and angiosperms.
Gymnosperms Most rely on wind dispersed pollen (very costly and ineffective) Angiosperms They have flowers, broad leaves Utilize insects for pollination Rapid reproduction (weeds)
Know the relationship between metabolism and rates of growth.
High metabolism is quick growth (because need large amount of resources and materials to grow quickly) Low metabolisms grow slowly
New discoveries: Understand the evidences for venomous and nocturnal dinosaurs.
Some believe that some dinosaurs had a venomous sack in the the skull above the teeth Sinornithosaurus, a bird-like dromaeosaur -Grooved teeth connected via groove to glandular pit (fossa) suggest venomous bite -Modern snakes with similar venom-delivery system via posterior teeth delivers venom onto bitten area (does not inject venom). In snakes these bites send victim into shock (does not kill).
What types of nests are made by dinosaurs and what does the arrangement of eggs reveal?
Some dinosaurs laid their eggs in nests. Up to 20 eggs in a clutch. Some eggs were laid in nests that also included hatchlings.
Evidence of keratinous projections from the skin of ornithischian dinosaurs.
Some dinosaurs show thistles or filaments that come out of their tail or back region The discovery of these branched integumentary structures outside theropods suggests that featherlike structures coexisted with scales and were potentially widespread among the entire dinosaur clade; feathers may thus have been present in the earliest dinosaurs
Be able to explain why tracks (footprints) are crucial to our understanding of dinosaur behavior.
Stride length can be determined which can tell us how fast these animals were. Can confirm the way they held themselves, whether they were bipedal or not. Helps us to know how these animals interacted and reacted to things.
What is the history of flight in terms of animals (dinosaurs, pterosaurs, insects) - who was first in the air, when did dinosaurs begin to fly?
THIS IS LONG: -Origin of birds: birds are specialized theropods-dromaeosaurid (descendants of theropods) Insects originated in the Early Devonian Period and were the first animals to have powered flight Oldest winged insects have four wings Dipterans (category of bees, wasps, flies, and mosquitos) reduced to one pair of wings Pterosaurs are archosaurs (same as crocodiles and dinosaurs). They are a diapsid reptile. Pterosaur means "winged reptile" and are first powered flight vertebrates Originated in Late Triassic (ruled skies for 140 million years); extinct 65 Ma Pterosaurs had hair like covering on wing and body. Pterosaurs wing is membrane supported primarily by the fourth finger. Like birds, the bones are pneumatic and very light. -Also like birds, they had a sternum that was keeled (bent) but not as developed as birds. This serves as an attachment plate for flight muscles Two groups of Pterasaurs: Rhamphorhynchoids and Pterodactyloids Rhamphorhyncoids have long tails and teeth Pterodactyloids have short tails and most lack teeth - Bats belong to the mamalian order Chiroptera, which means "hand-wing" - Earliest bats are from the Eocene (Ma), and have fully formed wings. - Bat Fossils are rare because of the delicate nature of their bones. - Unlike birds and pterosaurs, they lack pneumatic (air-filled) bones. - 3 fingers and thumb (see google doc for diagrams)
Dinosaur abundance in relation to the balance of terrestrial biota through time
Terrestial biota is organisms occupying a specific place together (populations of other organisms vs. population of dinosaurs)
Be able to explain the depositional environments for the Thaynes and Ankareh Formations and evidences used to indicate these environments. Environments we observed in the geologic record include: Shallow marine, tidal mudflats, Overbank deposits, Stream channels.
Thaynes is a shallow marine environment in the early Triassic Ankareh is the early Triassic and it was the sandstone. Sandstone contained abundant clay.
Know why coprolite preservation is to a large degree related to diet - for example, carnivore poop is more easily fossilized.
The bones found in carnivore droppings helps them to fossilize because they have a higher mineral content than herbivore droppings (which are just plant matter that decays). As Prof Britt says, they're basically fossils by the time they hit the ground.
Understand the significance of Anchiornis in terms of flight and feather coloring.
The dinosaur had four wings (early stages) and suggest older origin of birds
Understand the primary control on sea level.
In the late Cretaceous sea level was at an all-time high.
What are some of the problems faced when working with coprolites?
It can be really difficult to determine which dinosaur they came from as lots of them ate the same things. Hard to identify coprolites. Very few coprolites from herbivores have been found because they do not fossilize as well as the coprolites of carnivores.
Be able to diagram underprints, prints, and overprints and understand why the recognition of such track is important.
It's important to be able to tell what the true footprint is and not to be misguided by an underprint or overprint because you will not be getting truthful information about the animal that left the footprint (see google doc)
Was the K-T extinction gradual or sudden - and how do different paleontologists view the evidence?
K-T extinction gradual has to do with the idea that dinosaurs became extinct over time by a marked decline in diversity which is evident in the Hell Creek Formation. However this may be an effect of sampling and biases in preservation. K-T sudden extinction has to do with the meteor impact. Scientists were both enthusiastic and criticized this view.
Liaoning China's Jehol Fossils
Lagerstatte (phenomenal preservation) All kinds of vertebrates: frogs birds dinos, mammals; pterosaurs, fish Plants: earliest angiosperms Invertebrates: insects, snails, etc.
Preservation of Feathers
Lakes and areas with fine-grained sediment (volcanic ash) Preserves feathers and other softer tissues Earliest is early (mid) Cretaceous ~ 125 Ma BLACK MARKET (farmers find usually)
New discoveries: Understand the new evidence showing that even very large theropods possessed feathers.
Larger theropods have been discovered to have downy feathers (see below) which appeared like hairs Yutyrannus huali- largest dinosaur discovered with feathers in China The feathers of Yutyrannus were simple filaments, They were more like the fuzzy down of a modern baby chick than the stiff plumes of an adult bird." The idea that primitive feathers could have been for insulation rather than flight has been around for a long time
Know the types of weather and environments characterize the Late Triassic, Early and Middle Jurassic, Late Jurassic, Early Cretaceous, and Late Cretaceous.
Late Triassic: the climate was warm to hot yearlong Early and Middle Jurassic: monsoonal Late Jurassic: still monsoonal, but less so than earlier, due to continued breakup of continents. Semi arid climate common, but slightly warmer and wetter than earlier Jurassic. Early Cretaceous: Shift from monsoonal to wetter environment due to a) rising sea level and b) further continent separation Late Cretaceous: North America was warm temperate to subtropical. High sea levels
What were the names and locations of the major tectonic plates in the Mesozoic?
Laurasia is in the Northern hemisphere and Gondwana is in the Southern hemisphere.. They separated into continents and the climates worldwide were hot and wet like a greenhouse.
What is the primary driving force behind plate tectonics - that is, what is thought to cause most plate movements?
Lecture slides: density (thermal) differences, sinking edges of oceanic plates Wikipedia page: Tectonic plates are able to move because of the relative density of oceanic lithosphere and the weakness of the asthenosphere. The original source of energy driving plate tectonics was dispersion of heat from the mantle, but the current view (although still debated) is that the strongest of the principle driving forces is slab pull. Slab pull: plate motion is driven mostly by the weight of cold, dense plates sinking into the mantle at trenches.
Plants through time.
Likely played a major role in dinosaur evolution Gymniosperms until they became almost extinct and Angiosperms became prevalent-changed the dinosaurs diet
Be able to explain the relationship between body temperature strategies in extant animals and posture
Living ectotherms have sprawling posture and gait, living endotherms have upright posture. This correlation may suggest dinosaurs (who have upright posture) were endotherms.
Be able to explain the relationship between body temperature strategies in extant animals and feeding
Living endotherms maintain high body temperature and fast metabolism by consuming large amounts of food. Also, living endotherms process food in the mouth but dinosaurs do not have the same evidence of food processing in the mouth. It is impossible to tell if dinosaurs were endothermic or ectothermic from the structure of their jaws. Differences between hot & cold blooded meat eaters are few. In herbivores, ornithopods with dental batteries suggest they were efficient food processors. Sauropods used gastroliths in food processing.
Cycads are often listed as a primary food for herbivorous dinosaurs. Know why this is probably unlikely, based on our knowledge of extant cycads.
Many are toxic, leaves are hard with little nutritional value, and seeds harbor bacteria that produces toxic compound
What is the general consensus for dinosaurian metabolic strategies?
The general consensus is somewhere between the following ideas: Dinosaurs were a diverse group of animals metabolically; at some point (at least some theropods and ornithopods) were endotherms and others were ectotherms. Large dinos, the sauropods and big ornithischians, were gigantotherms as adults. Juveniles of these large dinosaurs, and the smaller dinosaurs, may have been either endotherms or ectotherms.
Be able to explain the relationship between body temperature strategies in extant animals and determinate vs indeterminate growth
The oldest known Tyrannosaurus was only 28 years old. Age is determined by counting growth rings in unremodeled bones. Based on a study of a number of specimens of varying sizes it is known that they grew rapidly - at about the same rate as elephants - and added about 4.5 lbs per day (which, coincidently, is the same rate of gain experienced by missionaries in the MTC). Ornithopods, such as the duck-billed dinosaurs, also grew rapidly based on histological studies. Sauropods also grew rapidly. If dinosaurs were ectotherms, how could they have grown so rapidly?
New discoveries: What type of dinosaur was Limusaurus and why is it unusual for this taxon to have a beak, and what evidence suggests it may have been herbivorous?
The only known beaked theropod from the Jurassic
What is used to determine the color of feathers on dinosaurs and other feathered animals?
The pigment cells the can determine the color by the shape of the pigmentation either a sphere or pill shape
Be able to explain the significance of Microraptor and Anchiornis as they relates to probable origins of flight among dinosaurs.
Microraptor (dromaesosarid) both winged arms and legs Discovered and described several years ago (latest) Anchiornis:
Be able to explain why most hypotheses for the extinction of the non-avian dinosaurs, with the exception of two, are unlikely and are little considered in the textbook and elsewhere.
Most of them make no sense (aliens) or have no scientific backing (aliens)
Was dinosaur growth more like birds and mammals or reptiles and amphibians?
Mostly like birds and mammals because of the slides they say they grew quickly and lived for about 30 years, having a quick growth and diminishing over time
Feathers are known to occur on an array of coelurosaurian dinosaurs. Since most did not fly, what purposes did feathers serve and what might have been their original function?
Origin of Feathers Insulation Display (hopping around, showing off) Gliding (Travel from the tops of the trees back to the ground) Running (used to lift off of the ground) *****Feather colors How we know them: Structural (shape of pigment bodies) 1. Pill shaped = black; 2. Irregular "spheres" = ruddy red Distribution of trace elements
Understand how paleontologists reconstruct dinosaurs and what is the basis for their reconstructions.
Paleontologists take bone scans and create muscular models of dinosaurs Based on skeleton, muscle attachment points, comparison with living relatives. How much muscle/fat - difficult to determine - make a digital model Color - speculation, except for feathers Skin - known for all major groups of dinosaurs. (skin impressions are known for ornithopod, theropod, and ceratopsian dinosaurs); Saurischians, ornithiscians, theropods, some saurischians are found to find feathers Feathers found on many theropods Hair-like feathers probably primitive dinosaurs and pterosaurs
Major clades that grasses and palms belong to
Palms belong to monocotyledon clade and is an angiosperm Grasses belong to ... PACMAD clade
Understand what determines the colors of sedimentary rocks and how the colors help in understanding depositional environments.
Reds = Iron + oxygen- wet and dry (rainy season causes floodplain) Greens = Iron (wet environment) never really dried out (fluvial/lucustrene) White/Grey = Never wet.
Be able to explain the relationship between body temperature strategies in extant animals and brain size
Relative brain size and complexity of dinosaurs compared to modern ectotherms reveals that dinosaurs only had slightly more complex brains, which in comparison to modern endotherms may be an indication that the dinosaurs were more active and required higher metabolism rates thus providing evidence for endothermy.
Based on recent discoveries of feathered dinosaurs, which groups of dinosaurs were likely feathered?
Saurischian line have been found to have feathers Theropods and descents are found to have at least downy feathers Some ornithischians have been discovered with feather like filaments Heterodontosaurs The discovery of these branched integumentary structures outside theropods suggests that featherlike structures coexisted with scales and were potentially widespread among the entire dinosaur clade; feathers may thus have been present in the earliest dinosaurs
Understand the two primary methods used to determine the mass of dinosaurs and which one is most commonly used.
Scale model and water displacement Multiple of crocodile mass and size Take bone structure and create digital model and calculate the model mass
The ontogenetic ages of tyrannosaurs have been the most studied - about how long did they live?
28 years and fully developed by age 20 years
Know the definition of a mass extinction, when the largest occurred, and when non-avian dinosaurs went extinct
A mass extinction is a relatively sudden, global decrease in the diversity of life forms. Largest mass extinction was the Permian-Triassic extinction about 250 million years ago. Non-avian dinosaurs went extinct 65 million years ago
Know what a form genus is and why such artificial groupings are useful.
A classificatory category used for fossils which are similar in appearance but cannot be reliably assigned to an established animal or plant genus, such as fossil parts of organisms and trace fossils.
In terms of the bolide impact you need to understand the history of the development of the hypothesis as an example of how science works. How did the theory develop, how was it accepted, and how long did it take to be rejected or accepted?
A large meteor that explodes in the atmosphere. It took 10 years to be verified because we needed to know where it landed. Looked for tectites and analyzed the sediment and dust given off from it.
What age are the giant fleas that were recently discovered and what is the evidence, aside from sized, that they victimized dinosaurs?
Fleas 10x larger than modern 22mm long, nearly an inch! Middle Jurassic, Mongolia Preserved in amber Non-jumping Large needle-like, blood-sucking proboscis Specialized hairs on legs indicate adaptation to haired or feathered prey Supports ideas dinos were endothermic (warm-blooded) Mouthparts suggest fleas are related to the clade that contains scorpion flies
Major groups of vertebrates that made an appearance in late Triassic
Turtles, pterosaurs, dinosaurs, and mammals
What is the largest known feathered dinosaur (clade and "family")?
Tyrannosauridae clade has the largest known dinosaur that is feathered Yutyrannus huali
Which were characterized by monsoonal systems and which by vast sand deserts, or by epicontinental seas?
Weather on Pangaea (started to break up at the end of the Triassic) was characterized by monsoonal seasons. Monsoonal: the majority of rain falls at a specific season. Winds bring in moist air causing wet summers, dry winters. Cretaceous is the sand deserts and epicontinental seas because of the change in sea level.