Re: re:Dinosaur Hunting techniques

[Greg Claytor <greg1@svpal.org>]

On Wed, 30 Aug 1995, th81 wrote:
> Tyrannosaurus does not LOOK very gracile, for two reasons:  1) at such a
> large size, gracile limb proportions look bulky.  However, compare the
> hindlimb of Tyrannosaurus with an elephant, a rhino, a Triceratops, even an
> Edmontosaurus.  You will see that the T. rex legs are more slender and have
> relatively longer tibiae and metatarsi.  2) The most famous T. rex mount in
> the world, AMNH 5027, has the wrong legs!! Since this specimen (a gracile
> morph) lacked hindlimbs, Osborn et al. added casts of the legs of the type
> (now at the Carnegie).  The type is the robust morph, and a larger
> individual!

Ok. So let me get this straight.  Somebody attatched the wrong legs?  
Also, I thought that T-rex had been sort of classified a slow poke because 
it's thigh bone (sorry, I don't know the correct term) was too short when 
coupled with the lower leg.

> Dromaeosaurids have about the least gracile limb proportions of any nonavian
> theropod (only therizinosauroids had worse!). Crichton aside, dromaeosaurids
> were probably not very fast runners relative to tyrannosaurids,
> ornithomimids, etc.  Instead, they were probably cat-like ambush predators,
> relying on short bursts of high speed, quick turns, and an all-out attack
> with all four legs and the mouth, too!

Deinonychus is still my favorite Dino and the Chetah is my favorite 
almost cat.  Your description of how a Dromaesaurid might have hunted 
sounds a alot like a chetah.  Would a cladist now clasify deinonychus 
as the grand father of the cheatah?  Sorry.  I got carried away.

> >     (and what with all the fused tendons along most therapods' tails,  you 
> >     don't see the completely supple spine like in a cheetah, anyways.  
> >     Therapods spines seem to have been reinforced to prevent exactly that 
> >     kind of movement.)
> 
> Actually, cheetah tails are held about as rigid as they can be, except at
> the base.  Cheetah's and other big cats use their tails as dynamic
> stabilizers, to turn on a dime at high speed.  This is exactly the condition
> we find in the Dromaeosauridae.

If I remember correctly a chetah can reach 70 mph and sustain that speed 
for about 20 to 30 seconds.  I've always understood that they actualy dislocate
their shoulders.  I don't recall reading anything that tells me dinosaurs 
came anywhere close to this speed, so I would'nt expect to see an adaptation.
Why the rigid tail?  Was the tail more for balance in turns only or could
it be a speed adaptation?

I hope I didn't loose your point Tom.  If I understood, you said 
that "relative" to T-rex the dramaesauridae were slower.  So if I had one 
of each animal, both 16" long, the T-rex would win the speed contest?

        Greg Claytor
        greg1@svpal.org
        Dino Nut