Re: definition of "reptile"

[John Alroy <jack@homebrew.uchicago.edu>]

Call me naive, but I was under the impression that the one thing that  
pretty much everybody working on primitive amniotes agrees on is that  
turtles are closer to diapsids than either are to synapsids. Maybe  
the molecular evidence is ambiguous or some of it shows support for  
the other two groupings (synapsid-diapsid or synapsid-turtle), but  
paleontologists have learned the hard way not to take that kind of  
thing very seriously (just look at all the needless to-do about the  
monophyly of rodents). Can someone provide a reference giving serious  
morphological/paleontological support for synapsida-diapsida or  
synapsida-chelonia?

Also, I don't want to be too anal about this, but maybe we should be  
careful about using "anapsida" as a synonym for "turtles and other  
stuff." The problem is that "anapsid" literally means "no holes,"  
i.e., no temporal fenestrae behind the orbits. Because this is the  
primitive amniote condition, when we say "anapsid" we run the risk of  
implying "primitive amniotes plus turtles" (a paraphyletic grouping  
if there ever was one), instead of "turtles plus their primitive  
relatives, whatever they are" (which we might mean instead). Maybe we  
should just say "turtles" and leave it at that, as I did in the above  
paragraph.