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Deinonychus




     Last night I skimmed over that paper that Ostrom and that other guy
printed in JVP last year (the same issue with the falling _T.rex_ 
article). Thier evidence for _Deinonychus_ predation on Tentonosaurus had
mainly to do with the frequency of association. _Tentonsaurus_ was the
most recently encountered dinosaur genus encountered in the Cloverly, and
_Tentonsaurus_ material is very frequently associated with _Deinonychus_
material, and vice versa.  _Sauropleta_, the second most common dinosaur
taxa in the Cloverly, is rarely or never associated with _Deinonychus_.
Not having read the paper very carefully, I can't speak for
possible different sedimentary settings for _Tentonsaurus_ and
_Sauropelta_.  
     At the Museum of the Rockies site Ostrom focused on in the text, the
_Deinonychus_ and _Tentonsaurus_ material was pretty badly disarticulated.
However, Ostrom cited scavenging, rather then fluvial transport as the
probable cause of disarticulation, partly because there was no prefered
orientation of the material, and secondly because the vertebral elements
of the tails were still articulated.  Speaking for myself, the second
piece of evidence to be rather suspect given that soft tissues covering
and holding the tail together could be more resistant to decay.
     So, the case for unusually frequent ASSOCIATION of _Deinonychus_ and
_Tentonsaurus_ seems pretty sound.  However, my impression of the text
(based on the quick skim that I gave it) seems to suggest that his only
reason for citing predation instead of scavening to explain association
(and the frequent occurrence of _Deinonychus_ teeth with the remains) was
that _Deinonychus_ was DESIGNED to be an efficient killer.  
     I also skimmed through my copy of Ostrom's original Yale Bulleton
(which I still haven't read) on _Deinonychus_.  He included excellent
figures of the material, including cross sections through the claws and
several points.  Although the other toe claws show very broad ventral
surfaces, the cross sections through the second tow claw definitely show
an unusually sharp edge. Not quite "sharp enough to shave with", but with
a horny sheath it certainly looks like it could have been pretty sharp (I
believe the same figures were used in Dinosauria).

LN Jeff
O-