Joao Lopes 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"?
Remember Malegasyan _Majungatholus_
(ex-pachycephalosaur, now abelisaur)
The Australian oviraptorosaur remains consist of a
surangular and a dorsal vertebra. The surangular may not even be a
surangular and some people are unconvinced that the dorsal belongs to an
oviraptorosaur. My opinion is that if it is a surangular, it probably
belongs to an oviraptorosaur, and that the dorsal may belong to an
oviraptorosaur, but it doesn't actually have any oviraptorosaur
synapomorphies.
The Australian neoceratopsian remains consists of an ulna
nearly identical to that of Leptoceratops. Since it is so similar, I
think the assignment to Neoceratopsia is probably correct.
The Argentinian oviraptorosaur is almost certainly an
oviraptorosaur because it shares several synapomorphies with other
oviraptorosaurs. The Brazilian oviraptorosaur seems to resemble Avimimus
and Ligabueino more than oviraptorosaurs in my opinion, and many others are
unconvinced of it's oviraptorosaurian status As far as I know, no
confirmed ceratopsians have been found in South America.
Quite a few dinosaurs have been found recently in various
Gondwanan continents that were not supposed to exist there previously.
These include ornithomimids and dromaeosaurids in Australia and nodosaurs,
stegosaurs and troodontids in South America. Of course, as Majungatholus
shows us, more complete finds may completely change our theories.
Mickey Mortimer
refs-
Frey and Martill, 1995. A possible oviraptorosaurid theropod from the
Santana Formation (Lower Cretaceous, Albian?) of Brazil. Neues Jahrbuch Fur
Geologie und Palaeontologie, No. 7: 397 (July 1)
Currie, P.J., Vickers-Rich, P., & Rich, T.H. (1996). "Possible
oviraptorosaur (Theropoda, Dinosauria) specimens from the Early Cretaceous
Otway Group of Dinosaur Cove, Australia." Alcheringa 20(1-2): 73-79.
Frankfurt, N.G. & L.M. Chiappe. 1999. A possible oviraptorosaur from
the Late Cretaceou of northwestern Argentina. JVP 19:101-105.