Dinosaurs
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- Ceratopsia novelties
- 1. rostral bone 2. high snout
- what are the groups of ceratopsians?
- Psittacosaurs, \"Protoceratopsids\", ceratopsids
- Psittacosaurs
- small, facultatively bipedal, fast runners?, leaf shaped teeth (gastroliths); tell us about extended parental care
- \"Protoceratopsids\" + Ceratopsids novelties
- 1. frill 2. large size, quadrupedal 3. dental batteries
- ceratopsia parallel ornithopods
- 1. larger 2. dental batteries 3. extensive head ornament 4. bipedal to more quadrupedal
- Protoceratopsids
- paraphyletic, griffin myth, often associated with the 1st discovery of dino eggs (Roy Chapman Andrews and Gobi desert)
- Ceratopsids
- monophyletic, much larger (semi-truck), novelty: horns, 2 groups: Chasmosaurs (small nose horns, large eye horns) and Centrosaurs (large nose horns, small eye horns), horns for defense/ combat, frills for attachment for jaw muscles and display
- Principle of Parsimony
- simplest explanation is the best one
- Sinosauropteryx
- 1st feathered dino found in 1997; primitive coelurosaur; chicken size; small, tubular structures on skull, neck, back, and tail; early branching
- Caudipteryx
- feathered dinosaur; oviraptor; turkey sized; well prserved, modern looking feathers on tip of tail and forelimbs; downy feathers on belly
- Sinornithosaurus = Dromaeosaur
- feathered dino; downy and noram featehrs
- Microraptor = Dromaeosaur
- feathers on arms and legs and tail; asymmetrical feathers for flight in modern birds
- Dilong
- feathered dino; recent discovery of tyrannosaurid with feathers
- What is a featehr?
- structure made from cells in outer skin layer, composed partly of keratin
- typical feather
- 1. main shaft = rachis 2. barbs (branches) 3. barbules (branches coming off barbs) 4. rachis expands at base to form a hollow tube 5. quill inserts into follicle in skin
- what are the three types of feathers
- body feathers, flight feathers, downy feathers
- body feathers
- prominent rachis, barbule interlocked, flat vane
- flight feathers
- body feather with asymmetric vane
- downy feather
- rudimentary rachis, jumbled barbs, long tangled barbules (lightweight, thermal insulation)
- feather evolution
- 1. hollow tube 2. barbs form, no rachis 3. rachis + barbs; barbs + barbules; no rachis 4. body feather 5. aerodynamic featehr
- what did feathers evolve for?
- insulation, courtship/display
- implications about feathers
- 1. birds not defined by feathers 2. non-avian dinos were birdlike 3. feathers didnt evolve for the purpose of flight
- features of living birds
- no teeth, wings, tarsometatarsus (fused metatarsals), perching foot, furcula (wishbone), hollow bones, sternum with big keel, pygostyle, carpometacarpus (fused hand bones)
- Archaeopteryx
- = old wing; earliest bird; had wings and perching foor like birds; unlike birds had a long tail, bladelike serrated recurved teeth, hands with claws, and metatarsals not fused
- are birds dinosaurs?
- yes they are Maniraptorian dinos
- reversed hallux
- 1st toe of birds is: much smaller than digits II-IV, moved to the back side of the leg, reversed
- early evolution of birds
- 1. Archaeopteryx: perching foot, flapping wings 2. Confuciusornis: loses tail = pygostyle 3. Hesperrornis: carpometacarpus, keeled sternum 4. living birds: no teeth
- What might the selective force for flight be?
- 1. Ground up (cursorial): fast runner, arms=gliders 2. arboreal (trees down): climbed up trees, glided down
- who are birds closest relatives?
- Microraptor-small, fast runner, but with feathers on legs
- Dinosaur distribution in space and time: caveats
- 1. Preservation: rock volume and differential probablility 2. collection bias
- bigeography
- the study of how the postion of land influences the distribution and evolution of life
- Hod does biogeography influence evolution of life?
- separation of land masses -> geographic isolation -> cant interbreed -> evolve independently
- species
- a group of organisms that can interbreed with each other
- endemism
- distinct faunas found no where else in the world
- Age of Dinosaurs
- I. Late Triassic : 225-200 Ma II. Jurassic: 200-145 Ma III. Cretaceous: 145-65 Ma
- Late Triassic (225-200 Ma)
- 1. Geography-pangea 2. Biogeography-low endemism = species had wide ranges 3. climate-warm, small latitudinal temp. gradient, strong monsoonal seasonality 4. Vegetation-no flowering plants (angiosperms), seed plants (cycads, conifersm ginkgoes) 5. vertebrates-sharks, plesiosaurs, ichthyosaurs, early synapsids, early archosaurs, tutlrs, [terosaurs, mammals, primitive theropods, primitive ornithischia, prosauropods
- Triassic (200-145 Ma)
- 1. geography-pangea breaking apart 2. biogeography-increased endemism 3. climate-warm, monsoonal 4. vegetation-cycads, conifersm ginkgoes, fewer ferns 5. vertebrates-earlly synapsids and archosaurs extinct, most large mammals extint, large plesiosaurs, most nondino very small, birds, more ceratosaurs small sauropods and small stegosaurs in early-mid, huge sauropods large stegosaurs small-med size ornithopods and carnosaurs in late
- Cretaceous (145-65 Ma)
- 1. geography-continents continue to split & flooded 2. biogeography-lots of endemism 3. climate-greenhouse: warm & wet 4. vegetation-flowering plants in early, diversity at end 5. vertebrates-mammals diverging, birds divergingm mosasaurs top of seafood chain, larger ornithopods (Hadrosaurs), ceratopsians, pachycephalosaurs, smaller sauropods, stegosaurs disappeared, tyrannosaurs
- endothermic
- heat (therm) from within (endo)-body heat of animal is generated internally, from metabolic processes; ex. mammals, birds
- ectothermic
- heat (therm) from outside (ecto)-relied on heat from the outside environment; ex. crocs, lizars, snakes, fish
- homeothermic
- able to maintain a constant body temeprature
- poikilothermic
- having a variable body temp over time
- metabolism
- sum of chemical reactions in the body; source of energy and heat
- extinction of non-avian dinos misconceptions
- 1. dinos are extinct (what about birds?) 2. all non-avian dinos were killed off in the extinction (dinos coming and going throughout Mesozoic; background extinction) 3. K/T mass extinction was the only mass extinction in Earth history (more ex. of extinctions in rock record, 5 big extinctions inlast 550 million yrs) 5. Extinctions dont affect evolution (extinctions do play a role in driving evolutionary change) 5. Dinos were the only ones to go extinct at the end of the Cretaceous (others died inclusiong some mammals, birds, plants, and marine organisms)
- uniformitarianism
- present is the key to the past
- biostratigraphy
- using fossils to tell time