Re: Rauhut's Thesis (long)

["Mickey Mortimer" <Mickey_Mortimer11@msn.com>]

Randall Irmis wrote-


> I'd like to see someone do a
> cladistic analysis to see where *sinensis* falls.  I do have a question,
the
> authors state that "D." sinensis has 5 premax. teeth, are there any
theropod
> groups that have this as well?

For the second question, yes.  Allosaurus and Neovenator both have five
premaxillary teeth.  Other allosaurids are too incomplete or poorly
described to determine, although Acrocanthosaurus only has four and is
sometimes considered an allosaurid.
The problem with a cladistic analysis of D? sinensis is that it is poorly
described and the figure is very inaccurate.  I coded it into Rauhut's
analysis based on my photo of the skull and a photo of the skeleton, with
some postcranial data from Hu 1993.  The result was 36432 trees of 687 steps
each.  The topology was identical to Rauhut's original analysis, except that
Dilophosaurus? sinensis was a member of the Carnosauria.  Its exact position
in this clade could not be determined, although it was not a spinosauroid
(Torvosaurus + Spinosauridae).  Of course Rauhut's Carnosauria includes
spinosauroids and some taxa generally considered basal tetanurines
(Magnosaurus, Afrovenator, etc.), so perhaps it would be best to call D?
sinensis a non-coelurosaur tetanurine until basal tetanurine relationships
are established.  Before everyone takes this as evidence D? sinensis is
definately a tetanurine, keep in mind no Dilophosaurus synapomorphies were
included in the analysis.  Thus, if the paired nasolacrimal crests and other
such characters were included, D? sinensis may have claded with D.
wetherilli.  A search enforcing a sister group relationship between D.
wetherilli and D? sinensis resulted in trees that were only one step longer
than D? sinensis as a carnosaur, so I don't think enough information is
known to make a decision on Dilophosaurus? sinensis' phylogenetic
relationships yet.

Mickey Mortimer