BIO 2135 Lecture Notes - Lecture 5: Flight Feather, Yolk Sac, Pulmonary Circulation
16 May 2016
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Amniote egg, little mini self contained aquatic enviro mature into mature animal. Both mammal and reptile kerotinized skin solution to water proof. So no loose water across surface, end up with new form of ventilation, costal bcz involve ribs, muscle between ribs, allows expantion, suction like ventilation, bring air into lung, to accommodate jaw muscles, modify skull. Originally just surrounded by chorion, outer casing of egg, chorion secrete chem. What we are doing, see happen add extra membranes, surround yolk sac, nutrients. Escape mechanism, some kind of covering, calcified surface, reptiles have leathery surface. Comes out in reptiles organism that needs to survive hunt function asap. Can hatch out and not function, and be taken caer of rents. Some have two, one group has one, diapsids, or synapsids: synapsids we are, so now you don"t compromise space in cranium. Diapsids, most abundant, but vast majority extinct, synapsids take over, mammals diverge.
