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Evolution

Trace the evolution of dinosaurs from Deinonychus to feathered dinosaurs and the development of flight in theropods. Learn about the adaptation of feathers for insulation, coloration, and flight. Explore the role of the enlarged claw in climbing and predation. Discover how smaller lineages eventually gave rise to modern birds.

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Evolution

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  1. Evolution • Dinosaurs

  2. Dinosaur Cladogram

  3. Originally...

  4. Deinonychus • Clearly a warm-blooded predator • Not some oversized, lumbering lizard. • Clade Deinonychosauria (Troodontidae & Dromeosauridae)

  5. The Feathered Dinosaurs • Originally evolved as insulation • Possibly a primitive trait for all dinosaurs! • Fossils from Liaoning show feather impressions. SINOSAUROPTERYX ROUGHLY 140MYA

  6. Feathers (cont.) • Analysis of melanosomes allowed scientists to reconstruct the colour of dinosaur feathers!

  7. Gliding • Feathers adapted to flying. • Development of enlarged second toe - useful for climbing trees. MICRORAPTOR GUI - 120mya

  8. Sinornothosaurus 122MYA • Like Microraptor, had four wings. • Flight feathers. • Venomous bite. • Orange and black feathers. http://www.youtube.com/watch?v=wIroCmC5yTg

  9. The Claw • Small Deinonychosaurids began spending more time on the ground. • The enlarged claw that evolved to climb trees became useful for holding down prey. • Claw could be used to climb larger prey, or attack prey’s jugular. VELOCIRAPTOR & PROTOCERATOPS

  10. Origins of Flapping • The larger dromeosaurids were too heavy to fly, but still had the flight feathers from their gliding ancestors. • Wings could be used for steering. • A flapping motion developed while holding down prey. http://www.youtube.com/watch?v=68BPPVVpN7s

  11. Flapping (cont.) • As smaller lineages emerged from the larger flapping dinosaurs, they were able to use that flapping motion for propelled flight. RAHONAVIS

  12. Extinction • As most dinosaurs were going extinct 65mya, the smallest dinosaurs, the birds, were able to survive. • Modern birds are classified as theropod dinosaurs. • Paedomorphy is the act of resembling an infant form. Near the end of the cretaceous period, selection favoured those raptors which resembled babies, and were light enough to fly. • Birds are paedomorphic dinosaurs.

  13. Then...

  14. Now

  15. Six Dinosaur Clades • Stegosaurids • Ceratopsians • Sauropods • Tyrannosaurids • Hadrosaurids • Therizinosaurids

  16. Stegosaurids

  17. Ceratopsians

  18. Sauropods

  19. Tyrannosaurids

  20. Hadrosaurids

  21. Therizinosaurids

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