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Dromaeosaur tracks (was: thanks for tracks & a question)

    Two of the things that have surprised me about some of the Theropods
from Maryland's Early Cretaceous is that apparent speed and agility.  Then,
there are the several tracks possibly made by Dromeosaurs  with that
second-digit's 'terrible claw'!  I had never thought about the tip of this
claw being so knife-blade thin and awesomely sharp (probably because I'd
been thinking mainly in terms of the claw bones we see, instead of the much
longer, sharper keratinous sheath that surrounded it in life), but a couple
of the tracks I've found here leave no doubt in my mind that this particular
Theropod was truly a 'Jack the Ripper'.
It surprises me that the tracks reveal the "terrible claw" at all; articulated dromaeosaur specimens have preserved the digit in a hyperflexed pose.  If the claw were habitually extended during locomotion, contact with the ground would cause wear on the tip, blunting the ungual phalanx and rendering it less useful as a weapon.  For example, a dog's or cheetah's primary manual and pedal claws are quite dull compared to the claws of cats (excepting cheetahs), which extend their claws only for such purposes as climbing trees and fighting.  Similarly, the cheetah's dew claws, which do not contact the ground, retain their sharpness, and are reportedly used by the cheetah to bring down prey by hooking or snagging.

In spite of your detection of the ungual in the tracks, your observation of the knife-blade morphology in the track suggests that the #2 pedal digit was not typically raking the ground during locomotion, but held clear to some extent.  Would you interpret these tracks to have recorded the digit as a consequence of the substrate being particularly soft (causing the foot to sink in deeply), as was apparently the case with numerous theropod tracks which preserve some impression of the #1 digit (even though it was probably held off the ground)?  Does the track show only the tip of the claw or the entire toe?  When are you going to publish?

Ralph W. Miller III  <gbabcock@best.com>

All we need now are some claw marks on trees which prove such animals were scansorial.   ;^)