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Re: [dinosaur] Chinlechelys (Triassic turtle) morphology and pareiasaur origin of turtles (free pdf)



If you claim Eunotosaurus is the earliest stem turtle, maybe the hand-wave is that stem-turtles didn't develop their trademark gait until the early Triassic...


Thomas Yazbeck


From: Thomas Richard Holtz <tholtz@umd.edu>
Sent: Sunday, April 4, 2021 8:21 AM
To: Yazbeck, Thomas <yazbeckt@msu.edu>
Cc: David Marjanovic <david.marjanovic@gmx.at>; dinosaur-l@usc.edu <dinosaur-l@usc.edu>
Subject: Re: [dinosaur] Chinlechelys (Triassic turtle) morphology and pareiasaur origin of turtles (free pdf)
 
>I'm actually very intrigued about the earlier Triassic turtle tracks.Was not aware of them - mirrors ichnofossils implying a much earlier origin of dinosaurs than body fossils attest. 

Of course, if Eunotosaurus were a stem-turtle, we would expect turtle tracks in the Permian, too...

On Sat, Apr 3, 2021 at 5:21 PM Yazbeck, Thomas <yazbeckt@msu.edu> wrote:
I'm actually very intrigued about the earlier Triassic turtle tracks.Was not aware of them - mirrors ichnofossils implying a much earlier origin of dinosaurs than body fossils attest. 


Thomas Yazbeck


From: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> on behalf of David Marjanovic <david.marjanovic@gmx.at>
Sent: Saturday, April 3, 2021 12:46 PM
To: dinosaur-l@usc.edu <dinosaur-l@usc.edu>
Subject: Re: [dinosaur] Chinlechelys (Triassic turtle) morphology and pareiasaur origin of turtles (free pdf)
 
> And at least superficially, the Casea-Eunotosaurus skull comparison in Fig. 27 is convincing.

Hardly, because – perhaps for reasons of copyright-related laziness – all three reconstructions in that figure date from the mid-20th century or earlier and thus ignore all the more recent research – the paper cites all of the more recent studies of Eunotosaurus and some on caseids.

Also, you can't do phylogenetics with three taxa. There is only one unrooted tree for three terminals. You need at least four terminal taxa. The phylogenetic analyses are much more important in that respect than fig. 27 (...though how they managed to get the two added caseids to come out so far from the Caseidae OTU certainly warrants a closer look).


--

Thomas R. Holtz, Jr.
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