Re: Dryptosaurus species specifics

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

Jaime Headden wrote-

>   Apart from *Dryptosaurus,* referral of *Deltadromeus* to *Bahariasaurus*
> is not confirmable. First of, the types are not fully comparable and
> possess distinctions. Portions of the hypodigm that Stromer referred to
> *B. ingens* have been shown to belong to *D. agilis*, but this does not
> neccessarily mean that *B.* and *D.* are synonymous. Similarly, it does
> not argue that *B.* and *D.* are, in fact, not sister species and the
> Egyptian material all does belong to *B.* This is the problem with largely
> dissarticulated material where general size and inferred affinity form a
> hypodigm.

The holotypes are comparable.  They share parts of dorsal vertebrae, pubis
and ischium.
The two taxa are very similar, and as I've said before, Sereno et al.
distinguished them by only three characters, two of which were due to his
misidentification of the distal pubis as an ischium.  The other is the
narrower ilial peduncle of Bahariasaurus' ischium.  Given the amount of
individual variation in theropod species (eg. Tyrannosaurus rex, Coelophysis
bauri), this is hardly an adequate criterion to base a new species on.  This
wouldn't be tolerated for distinguishing other taxa, and there's no reason
to continue supporting Deltadromeus either.  It's possible unpreserved
differences exist between the specimens, but that's not a proper excuse for
rejecting synonymy either.  Differences also exist between the holotype of
Carcharodontosaurus and the new incomplete skull (nasal rugosities extend
further anterior in holotype; maxillary teeth more symmetrical mesiodistally
in holotype; maxillary body higher in holotype; etc.), but you would hardly
recommend keeping them as separate species.  _If_ the Egyptian material
(which notably lacks an ischium) wasn't referred to Deltadromeus, there
might be some small reason to keep them separate.  But the fact you have
Egyptian material referred to a Moroccan species, except (conveniently) the
holotype of a previously named species, which is nearly identical, is just
ridiculous.  We need to stop killing old taxa like this.  Unless you have
further differences between the two taxa to use in your defense?

Mickey Mortimer