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David Peters <davidpeters@att.net> wrote:

> While others are scoffing at Ruben
> (and for good reason), there's another very large group of
> "believers"  that claims Pterosaurs Are Dinosaur
> Sisters (PADS) when no series of taxa anywhere within the
> Archosauromorpha shows any indication of a gradual increase
> in pterosaurian characters. 

Aside from pterosaurs themselves.

> In fact, as Bennett 1996 showed (and Hone and Benton 2008
> confirmed) when you remove hind limb characters 

Yes, but why would you want to do this?  Pterosaurs have legs, so why not 
include them in the analysis?  Most of the pterosaur bauplan has been 
comprehensively modified for powered flight, so (rather than representing 
convergence associated with digitigrade locomotion) the hindlimb skeleton may 
be best at retaining the ancestral condition.  

We see the same trend with birds: the tail, pectoral skeleton (including the 
forelimb), and to a lesser extent the skull show profound transformations as 
the skeleton became specialized for flight.  But the evolution of the hindlimb 
was far more conservative over the same period.  

Besides, the presence of skeletal pneumaticization and air-sacs in pterosaurs 
must count for something.  That wasn't known back in 1996.  Dinosauromorph 
affinities for pterosaurs are looking pretty good right about now.  

But what we really need are basal pterosauromorphs.  _Scleromochlus_ might fit 
the bill; but some of its features are open to interpretation.  Nevertheless, 
nesting pterosaurs inside Ornithodira is not dependent on the position of