Re: justification for excluding lagerpetids and/or pterosaurs from a phylogenetic analysis of the Archosauria

[Tim Williams <tijawi@yahoo.com>]

David Peters <davidpeters@att.net> wrote:


> Two: Sobral and Langer 2008. All prior works have ignored
> the fenestrasaurs. Right? That's why they were a novelty in
> 2000.


Sobral and Langer (2008) was a supertree, and so can be discounted.


> Also, please be my guest and list the three genus-based
> taxa that lead progressively closer to pterosaurs within the
> archosaurs as determined by the best study out there. I note
> that proterochampsids, erythrosuchids and proterosuchids
> keep making these lists, and I hope you can explain how you
> get pterosaurs to emerge from any of these.


You don't.  These archosauriform clades ((proterochampsids, erythrosuchids, 
proterosuchids) are recovered outside the Ornithodira+Crurotarsi clade.  AFAIK 
nobody has claimed that pterosaurs evolved *from* any of these groups.


The most recent phylogenetic analyses recover Pterosauria as the sister taxon 
of Dinosauromorpha, in a clade called Ornithodira (=Avemetatarsalia).  
Consequently, any characters that are shared exclusively between pterosaurs and 
any non-ornithodiran clade are either plesiomorphic (and were therefore lost by 
dinosauromorphs) or arose independently (i.e., they are homoplasies).  This is 
not my interpretation or opinion: this is what the cladogram says.



Cheers

Tim