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Reptile Derivatives

Reptile Derivatives. Birds and mammals. Archaeopteryx = “first” bird. Reptilian features teeth, tail, pelvis – no sternum skull features Avian (bird) features feathers, longer front limbs. Why feathers ?; insulation. Why fly?: to glide from tree to tree

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Reptile Derivatives

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  1. Reptile Derivatives Birds and mammals

  2. Archaeopteryx = “first” bird

  3. Reptilian features teeth, tail, pelvis – no sternum skull features Avian (bird) features feathers, longer front limbs.

  4. Why feathers ?; insulation

  5. Why fly?: to glide from tree to tree or to chase insects?

  6. Mammal lung = dead end – incomplete exchange of Oxygen Bird lung – one way movement = flow through and current counter current = greater efficiency and lighter weight.

  7. Hespirornis = toothed, flightless, loon like diving bird

  8. Rattites = worldwide, ancient flightless birds.

  9. 7 is Vega island, off of James Ross Island at tip of Antarctic Peninsula.

  10. Vega Island, Antarctic Peninsula

  11. Pleisiosaur front arm (fin)

  12. Vegavis, from Vega Island in Western Antarctica – Cretaceous in age (pre-meteor) A ‘duck’

  13. Origin of Modern birds (Neornithes) before end of Cretaceous

  14. Use of DNA • Gives relationship • Distance in time (if mutation at constant rate) • Does not use whole DNA but rather segments that evolve with time • Different authors use different DNA seqments.

  15. Unexpected relationships Hawks, falcons not related Penguins – albatrosses Flamingos – grebes !!! Ducks and grouse ratites

  16. Origin of Mammals

  17. synapsids, leading to mammals are the first group of reptiles • Based on differences from all reptiles and birds, mostly in features of soft anatomy.

  18. ventral aorta leaves heart, splits into aortic arches to gills • in amphibians , single vessel leaves heart, then splits to left and right sides to form dorsal aorta • in mammals and birds, same system in embryo, but in adults, ventral aorta splits back to the heart so the arches come directly off heart, one to lungs, others to body. In mammals and birds, finally reduced to a single arch • in reptiles, the split involves a twist. In mammals it does not, so the remaining aortic arch in on different sides in reptiles and birds vs mammals.

  19. Synapsids = mammal like reptiles

  20. Pelycosaurs = Dimetrodon

  21. Function of “sail” Camoflage? Swimming? Thermoregulation Note: nasty carnivore

  22. Therapsids

  23. How to make a Mammal • Develop for carnivory = active • Hair – warm bloodedness • Limbs; under body, toes of equal length • Teeth; regionalization, multi roots, cutting • Lower jaw – one bone • Not there – change in reproduction

  24. Hair, tooth regionalization, forward pointed toes of same length, limbs under body,

  25. Reptilian scales with sensory papillae in between. Papillae become hair – for insulation

  26. A definition of mammal = three bones in middle ear, one bone in lower jaw

  27. Mammals; monotremes, platypus and echidna Lay eggs.

  28. Echidna – egg in pouch, Hatches in 9 days – young in pouch for 12 weeks. Gets milk.

  29. Marsupials and Placentals – Parallelism And no shelled eggs

  30. Marsupial and placental reproduction; clevage total and equal - blastula forms with inner cell mass

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