Re: stegosaur stuff

["T. Michael Keesey" <mightyodinn@yahoo.com>]

--- Aegyptiacus@aol.com wrote:
> Hello list members.
> I'm still in a quandarry as to what stegos' back looked like.If I take the
> common opinion, they were (the spines) straight up in the middle of the back.
> This raises some questions:
> - what is the use of such an arrangement if the animal could be attacked from
> the side (I've read that dromaeosaurid teeth had been found from the late
> Jurassic age, so I'm thinking of side attacks)

CMIIW, but I don't think there are remains of *large* dromaeosaurids in the
Late Jurassic. Remember, most dromaeosaurids are pretty small (especially in
dinosaurian terms) -- lizard-eaters, not stegosaur-eaters.

That said, I'd think other predators were capable of side attacks, too.

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

I'm more impressed by porcupines.
IIRC, there is a depiction of a possible position in _Dinosaur Eggs and
Babies_.

> - 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)

I can think of a few issues with this:
- When articulated, the plates are found sticking up from the back, no?
- Many stegosaur species have only spikes, no plates, and these kind of grade
into each other, across species and within individuals.
- They don't seem to match the contour of the body, being pretty straight in
craniocaudal (or, if you prefer, anterior/posterior) view.

> - their close relatives had flat armored plates (ankylosaurs), so why not
> them?

Our close relatives eat termites off of grass blades, why not us?

One final thought: Note that stegosaurs went extinct long before ankylosaurs.
(At least, as far as we know.) Maybe this is because their defenses really
weren't as effective (although good enough to extend their range into the Early
Cretaceous).

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....

=====
=====> T. Michael Keesey <keesey@bigfoot.com>
=====> The Dinosauricon <http://dinosauricon.com>
=====> BloodySteak <http://bloodysteak.com>
=====> Instant Messenger <Ric Blayze>
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