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RE: Turtles and Crocodylians are not Reptiles - no? What are they?




Robert Takata wrote:


> What I've said is that extant turtles and extant archosaurs *probably*
> are the closest relatives each other. And yes, there is conflict
> between morphological and molecular data. 


I would say that the molecular data is even more problematic, given that the 
vast phylogenetic diversity of the Sauropsida is so poorly sampled among extant 
taxa.  Aside from turtles, we only have two surviving archosauromorph groups 
(Crocodylia, Aves) and two surviving lepidosauromorph groups (Squamata, 
Sphenodontia); and all four are quite derived within their respective clades.  
When it comes to inferring the affinities of turtles, I tend to put more faith 
in the morpho-based analyses.


> But here morphological data
> is somewhat problematic due to (a) highly morphological derived states
> in Testudines/Chelonia, (b) lack of less derived fossils.


Yes, both true.  Although (b) is true only if turtles are diapsids, rather than 
parareptiles (with Testudinata as sister taxon to pareiasaurs).  


Cheers

Tim


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