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Re: Proceratosaurus



On Sat, 2 Oct 1999, dbensen wrote:

> Well,  I'm sorry to ask this, but I have searched all over the web
> (including the listserve's archives) and I found virtually nothing about
> this next dinosaur I am researching, Proceratosaurus bradleyi.
> If anyone could give me information on the beast it would be greatly
> appreciated.  Your name would go down in history.
> Besides, since I've searched our archives and nobody's talked about
> Proceratosaurus bradleyi before, we will all be doing ourselves a favor.
> 
> Thanks
> Dan
> 
Proceratosaurus is based on a partial articulated skull from the Great
Oolite at Minchinhampton, Gloucestershire, England (Bathonian). The
specimen, which is housed in teh Natural History Museum in London (BMNH R
4860) was first described as Megalosaurus bradleyi by Woodward (1910: Q.
J. Geol. Soc. London 66: 111-115). At that time, only the right side of
the skull was prepared. Huene (1923: Bull. Geol. Soc. Am. 34: 449-458, see
also 1926: Ann. Mag. Nat. Hist. 17: 473-489 and Rev. Mus. La Plata 29:
35-167) removed it from Megalosaurus and proposed the new name
Proceratosaurus, since he believed it to be a close relative of
Ceratosaurus. Huene (1932: Monogr. Geol. Palaeont, Ser. I, 4: 1-361, Tafel
3, Fig. 1) also provided a new reconstruction of the skull. Paul
(1988: Hunteria 2 (4): 1-9 and PDW) regarded Proceratosaurus as a close
relative of Ornitholestes and referred it to the proposed allosaurid
subfamily Ornitholestinae. 
The specimen has now been prepared from both sides, but unfortunately not
completely freed from the matrix. It consists of the lower half of a
transversely compressed skull, including both premaxillae, maxillae,
jugals, quadratojugals, the anteriormost end of the nasals, the lower
parts of the lacrimals, the ventral process of the postorbital, the right
quadratojugal process of the squamosal, the ventral parts of the quadrates
and both rami of the mandible, the posterior ends of which are still
covered in matrix. The inside of the skull and the occiput have not been
prepared, so it is uncertain if any elements of these regions are
preserved. Two long and slender elements that probably represent hyoids
are also present.
Despite the fragmentary nature of the skull, bone preservation is
excellent. However, the systematic position of the animal is problematic. 
The nasal horn, which received so much attention, is only preserved in its
anteriormost part so that it is actually impossible to say whether it
represents a nasal horn or a midline crest on the skull. Anyway, the
position of this structure is very unlike that found in Ceratosaurus,
since it actually overhangs the anterior end of the premaxilla body
slightly. There is also little evidence for a close relationship with
Ornitholestes, other than that it is a rather generalised tetanuran skull.
A promaxillary fenestra is present, but it is very difficult to tell
whether a maxillary fenestra was present originally, since the inner wall
of te maxillary antorbital fossa is damaged on both sides. There is an
opening in the maxillary antorbital fossa in the right position on the
left side of the skull, but its edges are broken, and the other side does
not seem to show the same feature (again, there is an opening with broken
edges, but it is situated more dorsally than that on the left side). The
configuration of the premaxilla, maxilla, jugal, quadratojugal, and
postorbital is like in other basal tetanurans. An interesting aspect is
the rather large size of te maxillary antorbital fossa: This might
indicate coelurosaur relationships (used as a coelurosaur synapomorphy by
Sereno et al. 1996). The dentition is more heterodont than in most other
theropods, but unlike the situation found in Ornitholestes or
Compsognathus.
Hope that helps a bit!
Cheers,

Oliver