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Re: Australian Oviraptorosauria and Ceratopsia



João Simões Lopes Filho wrote:

<I read some years ago in a SCIENTIFIC AMERICAN about
polar dinosaurs from Australia. According to this
issue there was a oviraptorosaur and a neoceratopsid
in Australia Middle Cretaceous. Is it right yet? They
are zoogeographical complications. More recently, I
found a reference about an Argentinian
oviraptorosaurid or alike. Did oviraptors and
ceratopsids live in Gondwana? Or these ones are a
"pseudo-oviraptor" and a "pseudo-ceratopsid"?>

  These specimens show strong similarities to those
groups. In the oviraptorosaurs' case, this jaw may
look like an oviraptorosaur due to about three
features, but looks more like an indeterminate
maniraptoran, with similarities to both dromaeosaurs
(pers. ob.) or oviraptorosaurs, including a fused
coronoid eminence turned medially, an enlarged
external mandibular fenestra, and no surangular
foramen. An unfused and possibly concave articular are
primitive and do not neccessarily exclude the taxon
from the Oviraptorosauria, but I have my suspicions.
The dorsal vertebra is more extensively pneumatized
than most theropods, and could pertain to a wide range
of maniraptoran taxa, from dromaeosaurs (teeth in Oz),
ornithomimosaurs (*Timimus*? femora), to
oviraptorosaurs; it could be an Aussie segnosaur for
all we know, or a very unusual more basal theropod
(Currie, Rich, and Vickers-Rich, 1995).

  A partial sacrum with ilium from the Brazilian
Santana Formation has been applied to the
Oviraptorosauria, but lacks complete sacral
pneumatization, so may either be a juvenile
oviraptorosaur, ornithomimid, or dromaeosaur, or an
adult of the last two groups. It occurs to late to be
a oviraptorosaur adult unless secondary closure of the
sacral pneumatic formina is present, and this requires
an ontogenetic series to prove (Kellner and Campos,
1996).

  The partial cervical from Auca Huevo also may be an
oviraptorosaur, but is even more indeterminate, an
lacks a determinate study of oviraptorosaur cervicals
for comparison -- could also apply to ornithomimids or
segnosaurs (Hutchinson and Chiappe, 1999).

  There are a few more Gondwanan specimens exhibiting
maniraptoran features similar to those of
oviraptorosaurs, ornithomimids, or segnosaurs,
sometimes to two or all three taxa.

<Remember Malegasyan _Majungatholus_
(ex-pachycephalosaur, now abelisaur)>

  Most abelisaurs are classic Gondwanans, and it is
Laurasian abelisaurs like *Tarascosaurus* that make
the group unusual. But yes, there are some
biogeographical anomalies, should these South American
and Australian bones indicate oviraptorosaurs.

  On the other hand, the ulna described by Rich and
Vickers-Rich (1994) suggests it really does apply to a
leptoceratopid like *Leptoceratops* or
*Udanoceratops*, only Gondwanan, which was the point
of the paper by the above authors describing this bone
and *Timimus*, as an ornithomimosaur. Since I haven't
examined the taxa invlolved in the latter group, I
cannot give fair comment on it, and Currie wasn't as
SVP, or I would have cornered him -- darn the
Canadians! :) Oh well, at least I got to hook up with
Forster and Clark, and Norell and Chatterjee, and even
Sues, so I'm not too unhappy.


=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.

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