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Deinonychus hunting techniques (was Re: Benton et al.'s Supertree & The ecology of the Cloverly formation)



>In another post, Rutger Jansma wrote:
>
>> In a previous post a mentioning was made about a revised Deinonychus
>> restoration in light of the post by HP Tim Williams and the riggidty of
>> it's hands. This has made me look into the animals possible behaviour
>> again and perhaps some extra clues may lie within the ecology of the
>> area the holotype was found in [snip] Special interest goes to how
>> numerous were big rocks, mountains or that sort of structures?
>
>I'm not sure how the two are connected.  Are you proposing that
>_Deinonychus_ needed big rocks or mountains in order to launch itself
>against large prey?  _Deinonychus_'s hindlimb abilities would be sufficient
>for it to leap onto the back of (say) an adult _Tenontosaurus_.
>
Well, yeah, you may not have a time machine, but you can mind read! Now stop
doing it. :) This has something to do with Deinonychus leaping onto a large
prey item, for example Tenontosaurus. I don't doubt the hindlimb
possibilities of Deinonychus, but I only doubt the way this was used.
Deinonychus is a good jumper, sure thing, no trouble there, but...again, the
rigid movement in the manus causes me to think this way. Maybe the movement
was just enough to hold on with it's hands, but as an alternative view I
propose the following: A small pack of Deinonychus' drive a Tenontosaurus in
a small area with a couple of good rocks, a few jump up the rocks and they
launch themselves on the back of the prey, holding on witht their pedal
unguals, thereby also creating big wounds in the Tenontosaurus. The hands
are with this type of behaviour not necesairry, only for stabilisation
during the jumb. The same method was used in the possible aboreal
Microraptor and was retained in the more advanced genus Deinonychus. A
feather covering provided the lift to manouver and stabilized the animal
before it arrived at the back of the prey. Again, the neoflightlessness is
supported in the Dromeosauridae, although now based on (the lack of)
handmovement.
But as you have said, the hindlimb abilities of Deinonychus suggests also
that the jump could have been made from the ground. Still, the stabilisation
holds for the arms. You can laugh if you want, but this is the way the "new"
Deinonychus would be IYAM.
>
>By the way, I can only guess what _Carnotaurus_'s lifestyle could have
been.
>I have wondered if this gracile theropod was a scavenger that used its
short
>horns to 'dig' into titanosaur carcasses, in concert with the tearing
action
>of the jaws.
>
It sure would have help explain it's horns and the horns would have been an
advantage with the armor covering of the Titanosaurids. My only doubt is the
angle of the horns, they seem to have been to "dorsally" placed on top of
it's skull to be used in this sort of fashion. Some features in Carnotaurus
are so unique that finding the appropriate way of life for this animal might
be close to impossible (perhaps something to find out for Ethan Hunt ;)):
the flat topped tail, the reduced lenght of the skull and forelimbs, the
huge coracoids, the long straight neck and the large cnemial crest on the
tibia. At least the latter character could be evidence of an Olympic
sprinter and therefore could be indirect evidence for a predatorian
lifestyle for this genus. How the further oddities fit in, it beats me.
>
>Tim
>
Rutger Jansma