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RE: Spinostropheus gautieri identified as an ... alvare.. wait a second!




Mickey Mortimer wrote:

One distinct possiblity
is that not all of these remains came from the same taxon. There is no
indication Lapparent's first set of material (cervical vertebra, three
dorsal vertebrae, four dorsal fragments, three sacral fragments, three
caudal vertebrae, two caudal fragments, partial humerus, ulna, distal pubis,
distal femur, incomplete tibia, incomplete fibula, proximal metatarsal, four
metatarsal fragments, partial pedal phalanx) was associated.

Interestingly, Fig. 2 in Sereno et al. (2004), of a skeletal reconstruction of _S. gautieri_, does not actually show the caudals; cervicals, dorsals and the fragmentary sacrals are shown, as is the proximal humerus. This humerus fragment must have come from the holotype (or lectotype, I guess it should be called). I would not read too much into this, but it is worth noting. I wouldn't be surprised if Lapparent's original "type" specimen for _E. gautieri_ was a chimera.


Also, the most convincing alvarezsaurid characters are in the caudal vertebrae...

http://www.cmnh.org/dinoarch/2002Jul/msg00370.html



Indeed, the
ulna was stated to be isolated, and the proximal metatarsal comes from a
different locality. His second set of remains (cervical neural arch, two
dorsal vertebrae, sacrum, partial caudal vertebra, three manual unguals,
tibiae, distal fibula, proximal metatarsal, four pedal phalangeal fragments)
apparently come from a single individual. While this could allow the
referral of some of the first set of remains to the same taxon, if the first
set was completely disassociated, the humerus, ulna, pubis, femur and
metatarsal fragments would have no reason to be referred. Sereno et al.
only include unspecified vertebrae, a partial humerus and partial tibia in
the holotype of Spinostropheus. Incidentally, Lapparent did not designate a
holotype, so Sereno et al. are the first to do such for the taxon as far as
I know. Perhaps they did further resrarch to discover the pubis, femur,
fibula and pedal elements were not associated with the rest of the first set
of remains? Sereno et al.'s opinion on Lapparent's second set of remains is
unknown. They only code Spinostropheus based on their new material, which
is unhelpful in determining their thoughts on Lapparent's material. I'll
have to e-mail Sereno to find out what the situation is, and will report
back what I discover. Incidentally, I have no problem with the new specimen
and its homologs in Lapparent's material (the cervical photographed looks
similar, at least) being ceratosaurian.


But hey, at least he finally placed new material into an old poorly known
taxon, instead of nomen-dubiafying it and naming a new genus. :-)

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html

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