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Re: Abydosaurus mcintoshi, a new sauropod from the Albian of Utah

Mike Taylor <mike@indexdata.com> wrote:

> But I do think it's enough evidence to have shifted the null hypothesis
>  -- so that anyone who wants to challenge it really ought to make the
> effort to dig out some actual evidence themselves.  What Chure et al.
> wrote -- "the identified differences have not been defended as
> separating genera, rather than species, populations, or individuals"
> -- really doesn't advance the discussion at all.  It's an argument from 
> laziness, and all it does is muddy the waters (and perpetuate the
> discredited notion that the Morrison and Tendaguru formations shared a
> fauna).

The discovery of _Abydosaurus_ might actually have provided a good opportunity 
to test the monophyly of _altithorax_+_brancai_.  Instead, this monophyly was 
simply assumed by Chure &c, and _altithorax_+_brancai_ were therefore treated 
as a single OTU (_Brachiosaurus_) in the phylogenetic analysis.  

Also, as mentioned by Mike, _altithorax_ is from the Morrison, and _brancai_ is 
from the Tendaguru.  Thus, I would have thought that lumping the two into a 
single genus would require compelling morphological evidence.  This isn't the 
case.  IMHO, Taylor (2009) established a strong case for treating _brancai_ as 
a separate genus (_Giraffatitan_).  It's only historical tradition that's 
holding the two together.  If Janensch had *not* referred _brancai_ to 
_Brachiosaurus_, but had instead erected a separate genus, we wouldn't be 
having this discussion.