Re: Pygostyle

["Timothy Williams" <twilliams_alpha@hotmail.com>]

Grant Harding wrote;
>"Megalosaur-like"?  As I recall, only two arm bones are known from
>_Megaraptor_: a radius (or possibly ulna?) and one bit of a finger.  
(Could
>be wrong, though; my only ref is _Nat. Geo._ Dec. '97.)

My source was Novas's original description.  He says the ulna closely 
resembles that of a more primitive theropod, with the enlarged olecranon, 
unbowed shaft, and "L-shaped" articulation surface (with the radius) 
reminiscent of megalosaurids and ceratosaurs (Novas, 1998).

> I believe the idea
> was that _Unenlagia_ was the juvenile form and _Megaraptor_ was the >adult.

Could be right.  The hindlimbs of _Megaraptor_ are rather dromaeosaur-like.

Rob Meyerson wrote:

> Forgive my ignorance, but I was under the impression that Megalosaur was a 
> "trash can" grouping, where the connections between the different genuses 
> (sp?) was sketchy at best.  Did someone make sense of it while I wasn't 
> looking? :^)

_Megalosaurus_ is a valid genus, but its exact relationships to other 
tetanurine theropods is still unclear.  I think someone in England might be 
reviewing this genus, but I'm not sure.  Anyway, a close relationship may 
exist between _Megalo_ and the Torvosauridae.  If _Megalo_ is shown to be a 
member of this family, then it becomes known as the Megalosauridae.

There seems to be a bunch of large-sized, basal tetanurines that appear to 
be closely related to varying degrees, including _Megalosaurus_.  Perhaps we 
should wait for Tom Holtz's eagerly-awaited theropod phylogeny paper.


Tim

> Rob Meyerson
>
> ***
> Is it good if a vacuum really sucks?

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com