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South American theropods (was: Giant Allosauroids and "Big Ed")



On Tue, 3 Feb 1998 you wrote:

<<On a similar note I'd be interested to know what exactly the top
carnivores
were at the end of the Cretaceous in South America, Africa and
Australia.
As well as in Europe and the eastern part of North America, and just how
big they got.>>

A recent book by Dr. Bonaparte (Dinosaurios de América del Sur, Museo
Argentino de Ciencias Naturales Bernardino Rivadavia, 1996) dedicates a
chapter to the theropods of Middle and Upper Cretaceous. Most of them
belong to Abelisauria, and have been found in patagonian formations,
with the exception of Noasaurus and Unquillosaurus, from the NW of
Argentina. Some theropod material was collected in Brazil by Dr. Ll. I.
Price in the 60's, by it has never been published. This theropods of
South America can be caracterized as large predators (Abelisaurus,
Carnotaurus, Xenotarsosaurus), small predators (noasaurus) and
non-predators (velocisaurus). Of the specimen listed below only C.
sastrei was found articulated and almost complete (minus most of the
tail and distal part of the hindlimbs), the rest are known by incomplete
and generally disarticulated remains.

The list:

Carnotaurus sastrei (Bonaparte, 1985), its age has not been determined
accurately yet for stratigraphical studies in the region are few and
paleontological refs. incomplete, but it is assumed Albian to lower
Senonian. Length: up to 10 m.

Abelisaurus comahuensis (Bonaparte y Novas, 1985). Lower
Maastrichtian.Length: up to 10 m

Xenotarsosaurus bonapartei (Martinez et al., 1986). Probably lower to
middle Senonian.
Femur length: > 60 cm.

Noasaurus leali (Bonaparte y Powell, 1980), Maastrichtian from the
province of Salta
(NW of Argentina). Length: 1 m.

Genyodectes serus (Woodward, 1901). It is the first carnivore theropod
registered in South America, its stratigraphical and geographical
procedence is unknown. Known only from the front part of a skull
(premaxilla and both maxilla incomplete). Size estimated: medium to
large.

Unquillosaurus ceibali (Powell, 1979). Upper Cretaceous from Salta.
Known from an almost complete left pubis of about 50 cm length.

Velocisaurus unicus (Bonaparte, 1991). Formación Río Colorado (Neuquen).
(Probably omnivore or insectivore). Known only from a partial hindlimb
with pes almost complete.

Alvarezsaurus calvoi (Bonaparte, 1991) Also from Rio Colorado formation,
presumed Coniacian.

A small booklet named "Guia de los dinosaurios de la Argentina" by
Fernando Novas (also sold at the Bernardino Rivadavia Museum) includes
another notorious  alvarezsaurid: Patagonykus puertai, an
omnivore/insectivore about 2 m. long, from the Upper Cretaceous.

And last, but not least, there is Giganotosaurus carolinii, from the
upper Cretaceous, which can be included in the VERY large category, with
a length of 16 m., but I guess you've already heard about it   ;-)

Hope this helps,

Oscar Romero