Re: Bahariasaurus

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

B B wrote-


> The basis for this theory was an illustration I saw some time ago on the
> internet that depicted the pelvis of Bahariasaurus.  I noticed it seemed
to
> remind me a lot of Tyrannosaurus. I haven't been able to find it again
> though.  I have heard some other claims of tyrannosaur affinities in the
> pelvis of Bahariasaurus.  I also heard something about
> Dryptosaur/tyrannosauroid type material from somewhere in Cretaceous North
> Africa, including at least a forelimb and some metatarsals, but I am not
> sure what it was referred to (if anything).  If anyone has an illustration
> of the Bahariasaurus type material, I would find it useful for examining
> this hypothesis.  Now that I tought about it I have also heard about some
> teeth that supposedly belong to Bahariasaurus.  Not sure of the basis for
> this though.  If anyone knows more about this it may be helpful.  Thanks
for
> the info on the Indian teeth by the way.  I have suspected that there may
> have been some variation in basal tyrannosaurid teeth, based in part upon
> the teeth of Aviatyrannus before a final design was developed in the
> ancestors of the more derived and Tyrannosaurinae.  I suspected a
> relationship between Bahariasaurus and Dryptosaurus and/or Alectrosaurus
> based on the fact they seem to be primative tyrannosaurids or tyrannosaur
> relatives. As it stands I only have found good drawings of the type
skeleton
> of Dryptosaurus and drawings that are of the Alectrosaurus skull and a
> supposed forelimb claw (which may not belong).  As I think I stated
before,
> I am a little short on good info on this topic.  The reason I put it out
> there was to see what people with better information have to say about it.

Here are the only published illustrations of Bahariasaurus (from Stromer,
1934)-
http://students.washington.edu/eoraptor/Bahariasaurus.jpg
Only 8 (three sacral centra), 4 (pubes) and 10 (proximal ischium) can
definitely be assigned to Bahariasaurus.  Some of the other remains were
referred to Deltadromeus by Sereno et al. (1998), I think 2 (ischia) is
similar enough to Bahariasaurus to be referred to it, and perhaps 12
(proximal ischium) as well.
Chure (2001) referred Bahariasaurus to the Tyrannosauroidea, and one of his
supporting characters was ischial, but invalid.  See
http://www.cmnh.org/dinoarch/2002Aug/msg00488.html for details.
Tyrannosaurus' pubis differs from the Bahariasaurus holotype in having a
narrower pubic apron, narrower and much more proximally placed interpubic
foramen, and no distal interpubic notch.  Tyrannosaurus' ischium differs
from the holotype in having a less posteriorly projected ilial peduncle, a
proximodorsal process, narrower obturator notch, less extensive obturator
process, and thinner shaft that is more posteriorly directed.
I can't recall any reports of tyrannosaur-like material from Cretaceous
North Africa, though Carcharodontosaurus and Bahariasaurus have been
considered related to tyrannosaurids in the past (Paul, 1988; Molnar et al.,
1990; Chure, 2001 in part).
Any teeth referred to Bahariasaurus (such as those on some commercial fossil
websites) are done so without good cause, as the holotype and even published
referred material lacks cranial or dental remains.
Alectrosaurus
(http://students.washington.edu/eoraptor/Tyrannosauroidea.html#Alectrosaurus
olseni) seems closer to tyrannosaurids than Dryptosaurus is.  Only the
holotype is well described though (and photographed on the AMNH website-
http://paleo.amnh.org/fossil/find.html?A=Alectrosaurus&B=&C=&X=genus&Y=catal
ogue_number&Z=catalogue_number&K=OR&L=OR&img=yes).  The cranial remains
(part of two specimens described by Perle, 1977) are more fragmentary than
illustrations suggest, and most of the forelimb material of the holotype is
segnosaurian (except perhaps a couple small manual unguals).  Prior ideas
involving Dryptosaurus and Alectrosaurus being related (eg. Nessov, 1995)
were based on vague similarities between Dryptosaurus and the segnosaurian
material (both are long-armed with big claws).

Mickey Mortimer