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Re: Eunotosaurus and turtles
More later, except that I'd like to mention that I think I've already posted
Tyler Lyson's SVP meeting abstract which says turtles have their shoulder
girdle inside the carapace, but nonetheless in front of the ribcage. And, yes,
the shoulder girdle is cranial, not medial, to the "8th cervical" rib in
*Proganochelys* according to the text, drawings and photos in Gaffney '90. Just
a quick little reply to this here:
-------- Original-Nachricht --------
> Datum: Sun, 21 Dec 2008 16:47:43 -0600
> Von: David Peters <firstname.lastname@example.org>
> If you seek the ancestry and sisterhood of turtles, the best bet is
> still within the Pareiasauria,
I fear that's not the case.
For example, derived turtles have lost the basipterygoid joint, and so have the
pareiasaurs -- but *Proganochelys* retains it. Fine, said Lee (1997a or b),
that could just be a reversal (even though, I'd say, a very, very strange one).
But *Odontochelys* retains the basipterygoid joint, too...
Then, turtle teeth (now that we finally know what the jaw teeth of turtles look
like!) are utterly unspectacular cones. To get that from the leaf-shaped teeth
of pareiasaurs (somewhere between an ankylosaur tooth and a hemp leaf :o) )
would require a rather strange reversal.
Next, the pareiasaurs are supposed to have lost the cleithrum. Lots of
stem-turtles, stem-pleurodires and stem-cryptodires retain it, all the way to
the dorsal tip of the scapula. I have yet to get Rieppel's (2008) book chapter
where he apparently doubts the existence of a suture between the clavicle
("epiplastron") and the cleithrum ("dorsal process of the epiplastron") in
*Kayentachelys*, but from Joyce & Sterli (2008) I can't imagine how that
interpretation would work.
However, it goes without saying that my phylogenetic analysis won't have any
results anytime soon. I'm still fusing characters, and I'm still in the snout...
> and the best pareiasaur is the one without cheek flanges.
> Unfortunately it has been largely forgotten and hasn't made print since 1925.
And which one is that?
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