RE: _Dilophosaurus breedorum_

["Timothy Williams" <twilliams_alpha@hotmail.com>]

Tom Holtz wrote:

> Basically, everyone else thinks much as you do: but for Pickering's
> self-published, non-peer reviewed study, the agreement is that these are
> different sexual dimorphs of the same species.

_Coelophysis bauri_ shows a lot of variation in skeletal proportions, based 
upon the many, many specimens from Ghost Ranch.  This variation (among 
adults) may be gender-based.  Phylogenetically _Coelophysis_ is fairly close 
to _Dilophosaurus_, so it would be no surprise to find sexual dimorphism in 
_Dilopho_ too.

According to Colbert (1995), _Coelophysis_ specimens from Ghost Ranch may 
show an incipient double-crest in the sharp angle at which the lacrimal 
connects the skull roof.  I've heard that this character too is highly 
variable in _C. bauri_, insofar as the "crests" of some specimens seem much 
like the double-crest of _Syntarsus kayentakatae_.

I think the dual-crest of _Syntarsus kayentakatae_ was restored with 
_Dilophosaurus_ very much in mind.  The dual nasolacrimal crest in this 
species is not actually very obvious in the type specimen, nor in any of the 
referred specimens.


Tim



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