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Re: _Alxasaurus_; and oviraptosaur tails (?)
Jack the Conrad wrote:
< I've been doing a little reconstruction on some appendicular
skeletal elements of select coelurosaurs and something has struck me.
The scapulocoracoid of _Therizinosaurus_, _Herrerasaurus_ (as restored
in _The Complete Dinosaur_, don't know how much of it is really
known), and _Dromiceiomimus_ are all very similar. Going by the
general form of these, I was able to restore that element of
_Segnosaurus_ so that it looked similar (though the glenoid in this
taxon is notably different). _Struthiomimus_ possesses a more squared
coracoid than these others, but is similar overall. I would have
liked to have done a restoration of the scapulocoracoid of
_Alxasaurus_, but according to all the reconstructions I've seen, it
is poorly known (does anyone have any info here?).
These drawings convinced me that therizinosaurids were most
similar to ornithomimosaurs or herrerasaurids in the scapulocoracoid.>
This only enveigles the mystery further: are segnosaurs derived
forms of the Saurischia and Ornithschia transition, as Greg Paul (and
I think a few others, and I don't blame them) believes? Or are they
derived coelurosaurs, either closer to oviraptorosaurs or
ornithomimosaurs, or perhaps in a trichotomy, as Peter Buccholz (and
somewhat to myself, though I am more ambivalent than not) supports,
with good structure details confused by bad or incomplete perservation?
< Comparing the pelvis of _Segnosaurus_ with that
_Herrerasaurus_, _Ingenia_, and ornithomimosaurs, I found that the
pubis is most similar to that of herrerasaurids, the ischium most
similar to _Ingenia_, and the ilium as relatively unique.>
I, personally, see the form of the pubis, with its large propubic
boot and very small postpubic boot as more similar to oviraptorosaurs
and ornithomimosaurs, especially *Ingenia*, which has the best
preserved pelvis of the group I've seen.
< I then compared the known elements of _Alxasaurus_ pelvis with
these groups. Both the ilium and the ischium seem to be very
oviraptosaurian, with the obturator process of the ischium being
highly reminiscient of _Ingenia_.>
I'm waiting on *Alxasaurus*' ref right now, should have it before
Friday, but the illustration in _Dinosaurs: the Encyclopedia_ shows an
ilium quite similar to that of *Microvenator* and *Chirostenotes*, is
not wider in the front. Similarly, *Alvarezsarus* has an ilium,
ill-preserved, like *Avimimus*, which shows one end splaying out to
the side, and I don't know if perhaps this widening was at the front,
and not the back as illustrated in both animal's cases.
<One more question:
Has a good oviraptosaur tail been recovered? I'm sure that they have,
but I've yet to see a reconstruction of one and can't find one listed
in Glut's encyclopedia or in _The Dinosauria_?>
The Nakasato Dinosaur Museum Site
(http://www.dino-nakasato.org/en/indexMenu-e.html) has a page devoted
to a skeleton of *Ingenia*s nice tail, from a skeleton at the
Mongolian State Museum, alternatively pictured in _Dinosaurs of the
Flaming Cliffs_ [Novacek, 1995] and _Dinosaur Hunters_ [Psihoyos,
1996?]. From the pics on all three sources, I've constructed a
skeleton, very complete but for the trunk area (composited with
*Oviraptor*) at the following URL:
The accuracy of my reconstruction remains to be seen, but it does
show a nearly perfectly preserved tail, lacking only about five to
eight of the terminal-most vertebrae.
Jaime A. Headden
Qilong, the website, at:
All comments and criticisms are welcome!
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