TURTLES AS DIAPSIDS

["Matthew Troutman" <m_troutman@hotmail.com>]

     I've been out for a bit so whoever I owe an email to I WILL get 
back...
   
     Anyway, there has been a lot of stuff recently in the litt. about 
turtles being diapsids.  Olivier Rieppel has been arguing this very 
strongly recently with papers by himself (in Analysis of Complex 
Systems- Zoological, JVP, etc. 1994) and with Michael deBraga (in ZJLS 
and Nature).  According to Rieppel, and I agree, turtles are diapsids 
allied with lepidosauromorphs and are probably a sister-group to 
Sauropterygia (Chris Brochu, who works with Rieppel at the FMNH, can 
probably fill in the details if he so wishes).  This contrasts to the 
traditional views that turtles are parareptiles and/or anapsids.  Laurin 
and Reisz (Tree of Life among other places) argue that turtles are 
derived procolophonids while Michael Lee (the author of the now famous 
snake-mosasaur stuff) argues that they are paierasaurs.  I don't really 
buy either one.  As Rieppel points out, diapsids share many of the 
characters outlined by Laurin and Reisz and Lee.  Turtles also share 
some developmental patterns with lepidosauromorph diapsids.  

Matt Troutman 
m_troutman@hotmail.com

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