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13 Cards in this Set
- Front
- Back
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Solnhofen Limestone |
Limestone created by isolated lagoons that had little oxygen and lots of salt between reefs and land in the late Jurassic |
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Significance of Solnhofen Limestone |
Any organism that fell into the lagoons was rapidly buried and preserved in carbonic mud |
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Archaeopteryx |
Feathers that look remarkably like birds feathers for flight today Visible plumage - intermediate between dinosaurs and birds |
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Similarities between Archaeopteryx and birds |
Feathers, wings, wishbone and s-shaped neck |
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Differences between dinosaurs and birds |
Teeth, no beak, long tails, separated fingers, different hip structure |
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Hoatzin chick significance |
Chick actually begins with two fingers instead of bones fused - could indicate a dinosaur ancestor Look and act remarkably like ancient dinosaurs - locomotion on toes, etc. |
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Purpose of the wishbone |
Acts like a spring to bounce shoulder blades back into place after a strong downward stroke in flight |
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Similarities in dinosaurs and birds |
Pygostyle - nub of tail seen in modern dinosaurs Hollow bones - strength from struts |
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Possibilities of the origin of flight in birds |
Arboreal hypothesis, running raptor hypothesis, prey-corralling hypothesis, display and fighting hypothesis |
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Arboreal Hypothesis |
Transition from parachuting to gliding, flapping and then powered flight Objection: legs of theropods too long and it would be difficult to climb trees |
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Running raptor hypothesis |
Protofeathers provided lift for running dinosaurs Objection: protofeathers would have actually created drag when running |
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Prey-corralling hypothesis |
Feathers used as a method to corral insects to eat them Objection: gust of wind would easily blow food away |
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Display and fighting hypothesis |
Long feathers originally used for display, and the downwards "smashing" motion for flight resembles a cock fight - natural selection selected the highest jumping, best fighting birds for mating and survival |
