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Re: questions about the Odontochelys study
Mike Keesey wrote:
<Why have no terrestrial testudines lost the plastron? Or even just reduced it?
The only testudines with reduced plastra that I can think of are chelydrids
(snapping turtles), and those are aquatic. Am I missing any other examples?>
Sea turtles, which reduce the expansion of both dorsal and ventral plates to
finger-like strips. See also *Archelon* and kin.
I actually find the bizarre preservation curious, the presence of a nearly
fully formed plastron and unique ribs. All this tell me that dorsal osteoderms
would have been present but were lost. They might simply not fuse to the ribs
in this taxon, especially since neurals are apparently present. This seems if
anything counter to the original presentation of dorsally bare but ventrally
The thesis that ventra armor is good for aquatic armored animals does not
tell us why the dorsal armor of crocodilians are more dorsally than ventrally
evident, why the aetosaurs are terrestrial but have ventral armor, etc.
Jaime A. Headden
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)