Re: stegosaur stuff

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

Aegyptiacus@aol.com wrote:

> how did they mate whith such a prohibiting device on their backs?

Very carefully!  (An old joke)

>  wouldn't it be simpler to think that the plates were flat on the
> back (which would_IMHO_ have provided better protection against
> agression even with the use of the tail)

If stegosaur plates were mobile at the base, they could be oriented such 
that they could "point" in the direction of an approaching predator.  (It is 
doubtful that they could be swept all the way down until they were held 
against the flanks, however.)

Mike Keesey wrote:

> CMIIW, but I don't think there are remains of *large* dromaeosaurids
>  in the Late Jurassic.

I believe Brooks Britt (1991) reported dromaeosaurid teeth from the Morrison 
Formation.  These are comparable to _Deinonychus_ teeth in size.  However, 
in the absence of skeletal material, it's nearly impossible to determine the 
predatory abilities of these Late Jurassic dromies.

> Maybe this is because their defenses really weren't as effective
> (although good enough to extend their range into the Early
> Cretaceous).

Early Cretaceous stegosaurs have been found in Africa, Europe, and Asia.

> A post-final thought: Just realized that they went extinct roughly
> around the same time as the first known large dromaeosaurids. Given
> the poor sampling and the great number of other faunal changes,
> though, this could easily be coincidence....

The Early Cretaceous dromaeosaurid _Phaedrolosaurus_ (admittedly a 
poorly-known taxon) possibly measured at least 4m long, and co-existed with 
the stegosaur _Wuerhosaurus_.  Still, I would not be surprised if the 
super-sizing of dromaeosaurids in the later Cretaceous had something to do 
with the demise of the stegosaurs, which (AFAIK) did not persist into the 
Late Cretaceous.  (As we all now know, _Dravidosaurus_ is probably not a 
stegosaur, or even a dinosaur.)  Or maybe the tyrannosaurs did them in.  Of 
course, these hypotheses are nearly impossible to prove...




Tim

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