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Ceratopsia novelties
1. rostral bone 2. high snout
what are the groups of ceratopsians?
Psittacosaurs, \"Protoceratopsids\", ceratopsids
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
paraphyletic, griffin myth, often associated with the 1st discovery of dino eggs (Roy Chapman Andrews and Gobi desert)
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
1st feathered dino found in 1997; primitive coelurosaur; chicken size; small, tubular structures on skull, neck, back, and tail; early branching
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
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)
= 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
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
a group of organisms that can interbreed with each other
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
heat (therm) from within (endo)-body heat of animal is generated internally, from metabolic processes; ex. mammals, birds
heat (therm) from outside (ecto)-relied on heat from the outside environment; ex. crocs, lizars, snakes, fish
able to maintain a constant body temeprature
having a variable body temp over time
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)
present is the key to the past
using fossils to tell time

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