GLY-1102 Lecture Notes - Lecture 15: Polyphyly, Mesosaurus, Prokaryote
17 Sep 2018
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Amphibians rule for a brief period of time here. Turtles (cid:272)ould either (cid:271)e a(cid:374)apsids fro(cid:373) a(cid:374)apsid ge(cid:374)eti(cid:272) li(cid:374)e, or a(cid:374) a(cid:374)apsid (cid:862)reversio(cid:374)(cid:863) fro(cid:373) diapsid li(cid:374)e. Sails on the back, possibly to help cool reptiles. Pristerognathus large, almost cat-like organism, could have had hair and possibly been mammals. Polyphyletic group possibly have multiple origins, probably from diapsids. Mid ordivician, end of devonian, end of permian, end of triassic, end of cretaceous all big extinction periods. Permian extinction is most drastic, 60% of all species go extinct. Possibly a singular event that destroyed them, or a gradual grouping of events that led to ecological destruction, takes some time to get to low level of diversity. Ordovician mostly marine life dies off due to glaciation. Devonian peak in diversity at beginning, gradual decrease from there. Might not be a catastrophe, normal rate of extinction happening, peak is almost equal to trough, rate of generation of new species simply dropped.
