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Re: Dromaeosaur hunting technique (was BCF ET CETERA)



If I had more time I would have written something real similar to this 
like you said it is only speculation but I think it is real possible 
that this may have been the case.


>
>There are surely a variety of possible dromaeosaur hunting scenarios,
>depending somewhat on the size, speed, and body type of the prey item 
in
>question, and whether stealth, endurance pursuit, or pack hunting 
figure
>into your view.  In our mammal-dominated world, big cats may finish off
>their quarry with a precise bite, but the initial strike is often more 
a
>matter of batting with the paws, snagging or hooking with the claws,
>requiring only so much force as is needed to knock a running animal 
down,
>or to drag a standing animal to the ground.  While the claws of
>dromaeosaurids bear close comparison with those of cats, the remaining
>anatomy is so unique as to defy easy analogies with extant fauna.  
Those
>weary of reading unprovable hypothetical behavioral scenarios are 
advised
>to skip the following.
>
>Imagine, if you will, a _Deinonychus_ pack leaping onto a 
_Tenontosaurus_
>individual with all claws at once (each theropod pulling its neck back 
into
>an s-curve during the initial strike).  Perhaps the dromaeosaurs would 
then
>quickly jockey for position until each secured a firm grasp of the
>ornithopod with their forearms, freeing up the legs to facilitate 
raking
>the ornithopod to ribbons.
>
>Catching a relatively small animal might entail a powerful raking or a
>knockdown kick with the powerful feet (think cassowary or kangaroo),
>followed by firmly gripping the grounded prey with the hands, and of
>course, the obligatory raking with the claws of the feet.
>
>Dromaeosaur arm dynamics, though in some respects more restricted than 
the
>mobile articulations of their mammalian carnivore counterparts, should 
not
>necessarily preclude snagging capability.  Even if a dromaeosaur were 
to
>contact the prey with only one hand, this might be adequate, for the 
extant
>cheetah can knock a running gazelle off balance by hooking it with a 
dew
>claw.  (And the cheetah's dew claws, like the hypothetically raised
>dromaeosaur killing claws, are held off the ground at all times, and
>maintain their sharp hook, because there is no contact with the ground 
to
>dull them).  Once the prey falls, the theropod could use its arms to 
hook
>into its prey, securing the animal while administering lethal kicks and
>bites.
>
>In any case, even if the dromaeosaurid arm anatomy didn't enable rapid
>grasping of prey, the articulation would appear to be useful in firmly
>holding onto the prey -- "palms"-in --against the force of the kicking
>legs.  The semilunate carpals could even enable a dromaeosaur to tuck 
its
>phalanges posteriorly (in the manner of a bird folding its wings) in
>_diametric opposition_ to the force of the kicking feet.  With such a 
wrist
>configuration, this swinging of the wrist might occur inevitably (and
>fortuitously for the predator in this case).  Were the dromaeosaur to 
hold
>the struggling prey with the hands in the "palms"-forward position, its
>kicking feet could actually push the prey animal out of its hands, away
>from the predator, facilitating escape!  The "palms"-in articulation is
>utilized by small cats holding onto their prey (or their feline rivals)
>while raking with the hind claws.  The dromaeosaurid ability to tuck 
the
>hands back against the forearm could represent a further (albeit 
extreme)
>refinement of the technique.
>
>Hence, one could argue that natural selection might favor adaptations 
which
>enable a "clapping" grasp or posteriorly directed hands in 
dromaeosaurids,
>even if such adaptations are not specifically used in "snatching" prey. 
>Opponents of this view would argue that the articulations of the 
shoulder,
>arm, and wrist are more plausibly associated with flapping flight, and 
may
>have been present in primitive birds ancestral to the dromaeosaurs.  In
>that case, the described hunting scenarios may still have occurred, but 
the
>suggested behaviors would not have provided the driving force behind 
the
>perceived anatomy. 
>
>> Now, instead of grabbing a prey animal, suppose that instead, it was
>grabbing
>> onto a tree trunk?
>
>I wouldn't rule out that possibility, either, especially with those
>jackboots of theirs.  I would have appreciated more thoughtful
>consideration of arboreal theropods in the _Scientific American_ 
article,
>but it is not my place to tell others what to think or say.  I provide 
the
>foregoing to suggest some of the many ways in which the dromaeosaur
>forelimb anatomy could have possibly been beneficial in subduing prey 
aside
>from the problematical "power-clap in prey grabbing" technique you 
mention.
> That dromaeosaurs used their forearms in some way is not 
controversial,
>but just how they used them is the question.  In some matters, one can 
only
>speculate, and prepare for the inevitable flames.
>
>Ralph Miller III <gbabcock@best.com>
>
>"It's in the wrist action."     
> 
>


Larry Akins

"Quit Honking, I'm Reloading"


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