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NATS 1540 - Exam Review.doc

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Natural Science
NATS 1540
Robert Levine

FINAL EXAM REVIEW: DINOSAURS - WARM OR COLD BLOODED? DINOSAURS, A VERY SHORT INTRODUCTION (P. 110-121) Cold-blooded: take on the temp. of surroundings, controlling own body temp. through external factors (ex. sun/heat) Warm-blooded: remain a constant temp., can make their own body heat when ex. cold outside Legs, Head, Hearts, and Lungs (P.110-113): Dinosaurs built to move fast: have endothermic physiology Ectotherms: muscles build up large amount of oxygen, then needs to rest so muscles can recover Endotherms move quickly for longer because they have high-pressure blood systems and efficient lungs to replenish oxygen in their muscles Walking bipedally - does it mean endothermy Many mammals, all birds, many dinosaurs are bipedal Being bipedal requires rapid coordinating system: Brain must have constant supply of oxygen and heat to allow chemistry of brain to work Ectotherms shut down when cold Mammals + birds: because they have upright body posture: their head is above their heart, pumping more blood to their brain Reptiles: brain + head relatively same level Ectotherms spend a lot of time basking in the sun to warm their bodies - absorb the heat Dinosaur ``Sophistication`` and Brain Size (P.113-115) : Overall sophistication of dinosaur body design and function similar to modern endotherms Ectos: smaller brains, temp. vary throughout 24 hour cycle Endos: larger brains, require stable temp. to sustain it Bipedals believed to be smarter than reptile-like dinosaurs Latitudinal Distribution (P.115): Polar regions in Cretaceous Period: supports the idea that dinosaurs are endotherms or else they cannot survive: Today: ectos. Are incapable of living in high latitudes However, fossils show that the weather in high latitude places were sometimes mild, and had vegetation - therefore, dinosaurs may only be migrating, not necessarily residing there Ecological Consideration (P. 116-117): Endo + Ectos require different amounts of food to survive: The amount required is called the `running costs` Endos: mammals + birds - high running costs because what they eat is burned to produce body heat Ectos: need far less food - little is used to generate body heat The balance between predator and prey - use records in museums - problem: dont even know if these dinosaurs lived together Bone History (P.117-118): Bones of dinosaurs are similar to living ENDO. Mammals, rather than modern ECTO. Mammals + birds bones - high level of vascularization, ectos low levels Vascularization - ex. how rapid bone growth occurs Dinosaur Physiology: An Overview (P.118-120): Are dinosaurs simply endo - not necessarily The conditions - temp. back then affected the metabolism of endo+ecto Ectos: ate less than endo - able to survive longer Built like reptiles - cope better in desert-like conditions Endos: mammals - high-temp. Able to lose heat to the env. from bodies and adjust to cold or hot To adapt - require removal of water from body In desert-like conditions - fatal Heat gain + water loss + require large amount of food It was a time that favoured ectos Dinosaur Physiology: was it unique (P.120-121): Advantages of being larger: lose + gain heat slower Internal body changes little over time Larger = more muscles = more energy = more heat = body temp All these factors show that dinosaurs were more endo than ecto FINAL EXAM REVIEW: DINOSAURS AND BIRDS DINOSAURS, A VERY SHORT INTRODUCTION (P.122-132) Dromaeosaurian theropod transformed into an early bird Ex. Compsognathus: bird-like appearance: long legs, long neck, small head, large forward-pointing eyes With dinosaur features as well: claws, teeth in jaw, bulky tail Dromaeosaurian Theropods (P.122-124): Anatomical changes to the basic theropod body plans - some subtle changes, some not so subtle Thinning of the tail: becomes narrow Tail determines the posture: fast moving + more balance now The pubic bone points forward and downwards from each hip socket Shifts the weight of the body backwards, rotated backwards Shortened the chest in front of the hips: Birds have strong chest to help with powerful flight muscles V-shaped collar bones - separates shoulders for flapping wings Joints between bones of arm and hand modified so they can swing outwards and downwards with speed and force to strike prey When not in use - folded against the body - advantage Helps control the weight of the body, helps balance Very similar to when birds close or open wings during or after fight Archaeopteryx (P.124-125): Exhibits many dromaeosaurian theropod features: Long tail, thin set of revetebrae, tail feathers, hips pointing downward and backwards, v-shaped chest, jaws with spikey teeth, long arms - for extending and folding during flight, and clawed hands Considered important fossils: regarding feathers as unique to birds Chinese Wonders (P.125-127): Confuciusornis: fossils of birds from Early Createacous Skeletons included impressions of feather, beak and claws Compsognathus -- became Sinosauropteryx Found out that there were piles of soft tissue - feathers Protochaeopteryx: first to show presence of true bird-like feathers - attached to the tail and side of the body - more similar to dromaeosaurians than sinosauropteryx Velociraptor -- became Sinornithosauras Also had a `pile` of short fragments - feathers Microraptor, found in 2004 - `4-winged` dromaeosaurian Feathers attached to legs Birds, Theropods, and the Question of Dinosaur Physiology (P.127-128): Feathers do not make the bird Makes us wonder whether other dinosaurs (T-Rex) had `coverings` Dinobirds (ex. Microraptor) lived among true birds Endos: Small bodied feathers dinosaurs -- feathers helped generate internal body heat The outer layer of skin made it difficult to bask in sun - only ectos way of gaining heat Birds From Dinosaurs: an Evolutionary Commentary (P.128-129): Birds are potential endos: highly active, small, fast-moving, insulated self, reduce heat loss Modifications of growth patterns of normal skin scales - hair, feathers, etc. Feathers may have evolved based on their way of life (ex. mating) Flight was an `add-on feature` Persistent Problems (P.129-132): The Liaoning discoveries are younger than the discovery of Archaeopteryx Large dinosaurs seemed to be favoured - but dinosaurs suggested that small, insulated theropods were endo, and birds are endo Being a large endo = challenge The only group of dinosaurs that went against the general dinosaurian trend = small- bodied groups of dromaeosaurian theropods FINAL EXAM REVIEW: SUMMARY OF KNOWN EXTINCTION EVENTS Over the 550 million years that fossils of animals exist, six great mass extinctions are identified 1. The End Cretaceous Mass Extinction 65 MYA: Caused by asteroid impact Supported by iridium at the K/T boundary, along with shocked quartz and tektites This extinction eliminated the dinosaurs, 40% of marine life, 16% microfossil groups, some reptiles, 79% of plants, etc.
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