Re: questions about the Odontochelys study

[David Peters <davidpeters@att.net>]

D. Marjanovic wrote:

<<    as wondering which species the authors used when they say that  
turtle blood tests link them with 'diapsids'?


Several. Also, not just any diapsids: either as the sister-group of  
Archosauria or as the sister-group of Crocodylia.

And a phylogenetic analysis of sequence data is not a "blood test".>>

Confirming the sequence data, which characters can we look to as  
synapomorphies between crocs (or any other archosaur) and turtles?


<<    Was wondering which species Rieppel used when he linked turtles  
to lepidosaurs or squamates and sauropterygians?


Mostly *Proganochelys*, IIRC.  >>

Which species on the non-turtle side of the equation?


<<(Which, incidentally, is not trivial to interpret. Kordikova 2002  
claims to have discovered postparietals and tabulars in the skull,  
both never seen before and both supposed to be absent.) >>

Is Gaffney's interpretation of the skull gospel? And if so, which  
outgroup did Gaffney use to decide which skull bones were 'as is' and  
which were the product of fusion?

<<    How many millions of years link turtles to their closest known  
sister taxa?


Depends on what those are, obviously. Euryapsids appear sometime  
around the Early-Middle Triassic boundary, lepidosaurs in the Middle  
Triassic, crown-group archosaurs around the Early-Middle Triassic  
boundary (probably earlier), procolophonoids in I think the Late  
Permian, and pareiasaurs in the Middle Permian. >>

Is there enough time for the evolution of the carapace in each of  
these groups? Can we eliminate some possibilities due to lack of time?

David Peters
davidpeters@att.net