[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Pterosaur.net



David Peters wrote-

> All in all it sounds like no one has cared enough or was persistent enough, 
> to find the lineage of taxa that really demonstrates an increasing number of 
> pterosaur synapomorphies. Seems like anyone, even an amateur, could find a 
> lineage that was closer to pterosaurs than the vague enigmas that are 
> presented here. 
> 
> What is really a shame is the two studies that claimed to figure this out 
> once and for all (Hone and Benton, 2007, 2008) came to their conclusions by 
> ousting the other candidates, rather than testing them head to head and toe 
> to toe. Yes, it was a supermatrix, but Hone & Benton chose that route when 
> they could have chosen to actually look at the specimens. Too bad that study 
> also failed to find a distinct lineage of proto-pterosaurs.

I have to agree with David that Pterosaur.net is disappointingly vague 
regarding pterosaur origins.  I would have enjoyed seeing the synapomorphies 
shared with protorosaurs vs. dinosauromorphs, as opposed to just claiming 
things are uncertain.  But then again, I would have liked to see material lists 
for taxa, diagnoses, references, comparisons of taxonomy, etc..  Maybe those 
will be added in the future?
 
What was especially problematic about Hone and Benton (2008) is that their 
matrix contains repeated taxa.  For instance, Lepidosauromorpha is an OTU, but 
so are Gephyrosaurus, Sphenodontia and Squamata (which ARE Lepidosauromorpha).  
Similarly, Choristodera is an OTU, but so are Champsosaurus, Lazurussuchus and 
Cteniogenys (which ARE Choristodera).  By itself, this only indicates laziness 
or taxonomic unfamiliarity on the authors' part, but what's disturbing is that 
the lepidosauromorphs do not clade with Lepidosauromorpha, and the 
choristoderes do not clade with Choristodera.  Instead, choristoderes form a 
clade which is closer to other archosauromorphs than Choristodera (with 100% 
bootstrap support).  Similarly, lepidosauromorphs form a clade two nodes more 
derived than Lepidosauromorpha (with Younginia in between them, both nodes 
supported with 100% bootstrap values).  So if the supermatrix couldn't get 
lizards to clade with themselves, what's the liklihood it got pterosaurs to 
clade with their real sister taxon?
 
Mickey Mortimer