Ceratosaur stuff

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Jaime Headden wrote:

> It was a very small animal, as is obvious from Luis Rey's painting of 
> the Auca Mahuevo site; the sauropods there could squat and kill these 
> critters, even when they were full size.

Perhaps that explains the cranial horns of _Carnotaurus_ and _Majungatholus_
- a deterrence against being sat on by angry sauropods!


Mickey Mortimer wrote:

> And the metatarsus lacks the slender second and fourth metatarsals seen 
> in  several abelisauroids.  Metatarsal IV is actually much broader than 
> III  (sort of like troodontids).  So this settles the debate as to 
> whether abelisaurids have this character, allowing it to be used to 
> group Noasaurus, Masiakasaurus and Velocisaurus in a Noasauridae to the 
> exclusion of abelisaurids.  

Which state is primitive?  Or are both metatarsal proportions derived
relative to coelophysoids and ceratosaurids?  In other words, can you be
certain that the proportions seen in _Noasaurus_, _Masiakasaurus_ and
_Velocisaurus_ are not primitive for the Abelisauroidea?

> Whether Ligabueino, Elaphrosaurus, Laevisuchus or  Chuandongocoelurus 
> are noasaurids too, or somewhere else in the Ceratosauria remains to be 
> clarified. 

_Chuandongocoelurus_?  Haven't heard anything on this fellow for quite a
while.  What makes you think it could be an abelisauroid? - thereby making
it the earliest (Middle Jurassic) member of the clade.  (Assuming
_Piatnitzkysaurus_ is a basal tetanurine, not an early abelisaur as avered
by Currie.)

By the way, many thanks to Mickey and Mike for the juvenile theropod info.
Much appreciated.




Tim



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Timothy J. Williams, Ph.D. 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 9359