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Re: DROMAEOSAUR "SICKLE" CLAWS



 Peter Von Sholly <vonrex@gte.net> writes:
> I agree.  Tracy Ford says the really large claw (on _Deinonychus_) is
known
> from a single specimen.  And _Dromaeosaurus_ claws are nowhere near that 
> big, from what I can see.

Chris Campbell writes:
>This, I think, should be a critical part of determining the hunting
behavior of >dromaeosaurs.  How much force can they exert with their jaws? 
Most of the >discussion here's been centered around that one big claw;
before we can >really talk about behavior, though, we have to see what
other characters might >support a given lifestyle.  Force per unit area
exerted by the jaws is a huge >part of that, at least in modern carnivorous
mammals (and birds?  Do raptors >have especially powerful jaw/beak
muscles?); if that force isn't terribly great >any notion of pack hunting
in these animals is kinda silly if the claws aren't >used as weapons.

According to <Dinosaur Discoveries> Issue #2, a recent return to the Lower
Cretaceous Cloverly Formation (whence came the original _Deinonychus_
material which John Ostrum excavated and described in the 60's), conducted
by the Museum of the Rockies and a crew of volunteers, succeeded in
recovering a number of _Deinonychus_ skull elements as well as two feet,
two hands, and an assortment of other bones ("many dozens of bones" in
all).  In this brief article, Dr. W. Desmond Maxwell and Dr. Lawrence M.
Witmer describe new information gleaned from the skull elements, which are
reportedly sufficient to enable an accurate reconstruction of the entire
skull.  Among the distinguishing features germane to our topic is a robust
parietal sporting a large nuchal crest which would have anchored those neck
muscles used in retracting the head vigorously "probably during feeding." 
The robust frontal and parietal are said to compare much more closely to
those elements of _Dromaeosaurus_  than to those of  _Velociraptor_. 
Further comparisons cited in the article distinguish the skull of
_Deinonychus_ as being quite unlike _Velociraptor_ in overall proportions. 


Drs. Maxwell and Witmer published the following papers on this new
_Deinonychus_ material:

MAXWELL, W.D. and  L.M. WITMER, 1996, New material of _Deinonychus_ 
(Dinosauria, Theropoda), <Journal of Vertebrate Paleontology>, 16(3)
Supplement: 51A.

WITMER, L.M. and W.D. MAXWELL, 1996, The skull of _Deinonychus_
(Dinosauria, Theropoda): new insights and implications, <Journal of
Vertebrate Paleontology>, 16(3)  Supplement: 73A.

As I do not have ready access to these papers, I wonder if others on the
list could comment on (1), the size of the #2 pedal claws in relation to
the overall size of the _Deinonychus_ elements recovered (the DD article
states that four of these claws were found during this excavation), and
(2), does the more complete skull material give us a clear picture of the
animal's biting strength?

Speculations of dromaeosaur "kitty cat kicking" aside, I am keeping an open
mind about the behavior of these amazing creatures.  When it comes to
dinosaur behavior, I think that's usually the most reasonable approach
(unless you're a movie producer).  If dromaeosaurs didn't use their pedal
unguals offensively, that's front page news.  Right up there with John
Horner's characterization of _Tyrannosaurus rex_ as a strict scavenger (a
view immediately embraced by paleontologists worldwide).  OK, John Horner
does see _T. rex_ picking off an occasional live animal once in a blue
moon.

Ralph Miller III <gbabcock@best.com>

Q: What was T. Rex doing with those puny little arms?
A: Holding the microphone while he was singing "Get It On (Bang A Gong)."