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Lecture 8

lecture 8

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Michaelde Braga

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Lecture 8- Lepospondyls and Lissamphibia -When point is emphasized more (like stapes or evolution of the limb look at pdf)->those are the things that need to focus on; dont worry about memorizing all the taxa names or all the character traits (bc theres so many listed) but need to know some of the basic things (like interterygoid vacuity in temnospondyls). If theres 7 or 8 characters, not going to ask to list all of them. As long as you have a sense of what character traits diagnose a particular group (like one good character trait or something prof emphasized) then focus on that. - Lissamphibia- if group is monophyletic, that means frogs, salamanders and caecilians have a common ancestor but there is a lot of controversy because the modern amphibians today have become so highly derived in their general appearance that its very hard to find direct links to any fossil groups-> getting lucky w frogs and salamanders but so far, caecilians are a problem - Lepospondyls- group that includes the microsaurs (recall: initially thought of as a reptile but realized its not- just a specialized amphibian); will spend quite bit of time on lepospondyls 1.) Lepospondyls- appear in the Mississipian united by a few characters (synapomorphy); most significant one is: NO labyrinth infolding in teeth (the teeth are infolded, creating a labyrinth type structure (like a maze) and has little grooves all around it)- no more of this grooving Large cylindrical centra: centra associated w the vertebrate in most other groups tend to be combinations of various elements. In lepospondyls, they look like a spool of thread (very different)- still hollow 2.) Lepospondyl Diversity- fairly diverse; 3 major groups: Aistopoda, Nectridea and Microsauria; Microsaur is probably paraphyletic 3.) Aistopods: wormlike, limbless creatures- not worms, they are proper vertebrates Snake-like in appearance; quite small appear in the Mississipian and continue to Permian; they disappear in the Lower Permian (not sure why bc it wasnt bc of a mass extinction) oldest known group member is Lethiscus 4.) Aistopod synapomorphies:
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