ARCHOSAURIAN TURTLES?

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

<<The theory of relativity does predict events not available for study,
but so does cladistics.  You said yourself we don't have all the
fossils, and one doesn't always get an "answer" they were looking for.
 Take Olivier Rieppel at the Field Museum whose recent cladistical
analysis suggests turtles may be archosaurs!  Since the common
"accepted" hypothesis was that turtles represented anapsids, the most 
ancient and "primitive" reptiles, Rieppel should have gotten what everyone 
else did if there was no real predictive power or everything was assumptions 
in cladistic methodology.  Instead, many researchers have good reason to go 
back and look at turtles more seriously.  Are they archosaurs?  That's the 
risky prediction, without lots of fossils pointing the way.>>

Sorry in advance for the small font that hotmail sends out on every email.  
It truly isn't my fault.

Rieppel didn't suggest that turtles were archosaurs, that was Hedges and 
Poling (1999).  Rieppel found out in his 1993 analysis trying to determine 
sauropterygian ("euryapsid" in the paper) relations, that turtles fall basal 
to diapsids (above captorhinids) as a whole with the particular data set he 
was using.  Most prominently with Michael DeBraga (1997), Rieppel found that 
turtles are probably lepidosauromorphs, based on several features but most 
prominently the advanced mesotarsal ankle joint (note that Hedges and Poling 
have turtles as closer to crocodilians than birds, but it is the bird group 
that has the AM ankle).  Rieppel (1999) summarized his findings quite 
eloquently in his commentary on Hedges and Poling's molecular analysis.  
Also of interest is that he cites a paper in prep with Riesz that shows (as 
his many earlier analyses did) that sauropterygians are probably the closest 
relatives to turtles.  Rieppel (1998) shows Testudines as a sister-group to 
thallatosaurians+sauropterygians (another new arrangement).

I take this over Lee's turtle origins stuff.

Matt Troutman
m_troutman@hotmail.com


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