SPINOSAUR SYNONYMY

[Tetanurae@aol.com]

This message may be a little premature, seeing as the 13 Nov 98 Science hasn't
arrived at the UW library as of yet, but I feel I must take issue with some of
Sereno et al's synonymies.

First off, they sink Cristatusaurus lapparenti into Baryonyx walkeri.  From
the published figures and descriptions, I think that this is unwarented.
Taquet and Russell (1998) write:  "Anteriormost premaxillary alveolus
relatively large, lateral alveoli *uniformly closely spaced*."  

This is in opposition to Charig and Milner 1997 who, in figure 2 C, illustrate
the premaxillae of Baryonyx walkeri with the alveoli (and teeth) of
premaxillary position six and seven very closely appressed on both the right
and left sides.

The premaxilla of Cristatusaurus is also relatively shorter and more "hooked"
in appearence than that of Baryonyx.

Taquet and Russell also state: " Maxillary and dentary teeth latterally
compressed in cross section."  Again, look to Charig and Milner 1997 Figure 3,
Figure 14, and Figure 18, where the maxillary and dentary teeth and alveoli of
Baryonyx walkeri are almost circular in cross section (Darren, correct me if
I'm wrong on any of my Baryonyx musings).

As for Sereno et al's claim that most or all of Spinosaurus maroccanus belongs
in Spinosaur aegyptiacus, I cannot comment without having either Stromer 1915
or Russell 1996.  If any of you have either of these I would love to set up a
ref trade :-)

As for Tom's suggestion that Taquet and Russell's S maroccanus snout almost
certainly belongs to Suchomimus...  The snout assigned to S maroccanus has a
distinctive pattern of premaxillary dentition.  Tooth one is small, teeth two
and three are large and paired up, teeth four and five are smaller and paired,
and six and seven are small too and paired up.

This is different from the condition I see in photos of Suchomimus, where
premaxillary teeth 2-4 are very large and in a group, and 5-7 are small and in
a group.  How much of this is real, and how much is reconstruction, is
anyone's guess, I will just wait a few days til I see the paper.

Peter Buchholz
Tetanurae@aol.com

--------------
Charig, A J and Milner A C.  1997.  Baryonyx walkeri, a fish-eating dinosaur
from the Wealden of Surrey.  Bulletin of the Natural History Museum of London
(Geology) 53:11-70.

Taquet, Ph and Russell, D A.  1998.  New data on spinosaurid dinosaurs from
the Early Cretaceous of the Sahara.  C. R. Acad. Sci. Paris, Sciences de la
terre et des planetes 327:347-353.