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Re: Velociraptor footprints



On Fri, 25 Jul 1997 11:39:49 -0700 Sam Girouard <sampaula@pacificrim.net>
writes:
>>> Don't cats do this, more or less?
>>Yes, as you said, more or less.Cat's feet are a little different than
>>Velociraptor's though and you don't have entire toes held up.
>
>The feet of cats have rather extreme morphological adaptations that 
>allow
>for >all< of the toes to retract.

I assume you mean all the *claws* to retract, not the toes.

[snip]
>Extant ratites, that have been known to kill even humans with their 
>inner
>digit's claw, do fine without carrying their second digit off the 
>ground. 

Extant ratites have blunt toe claws, not a sharp, curved claw like a
dromaeosaur.  And as I understand it, it is the force of the whole foot's
blow that does the damage, not the claw by itself.

>[snip]
I can't see 
>how
>>giving an Ostrich a raised inner digit would affect it's impressive
>>ground covering abilities in the least---Speculation as usual, Sean 
>C.
>
>Wouldn't the constant hyperextension of the second digit cause a 
>decrease in
>the performance of the rest of the locomotory musculature of the hind 
>limbs? 

One would expect this to be the case. 

> Of the tens of thousands (hundreds 
>of
>thousands?) of small theropod tracks that have been documented, NOT 
>EVEN ONE
>unambiguously shows a retracted second digit. Period.>

None of them show the imprint of that sharp claw touching the substrate,
either.  They do show other claw imprints, though, so either this sickle
claw had its own sheath and was retracted (but then we should see a
consistent set of tracks with one claw never showing), or it was walked
on and blunted, or its tip just barely touches the ground or is held a
hair above it.

> Occam's Razor 
>tells us
>that small theropods simply didn't carry their second digits off the 
>ground.

>From the trackways so far seen, this is true.  This just doesn't seem
settled by the evidence in either direction, except the skeleton has that
darn sickle claw on the foot.  Sure is a head scratcher.  What if the
sickle-claws avoided soft substrates and never got their tootsies
preserved?

Judy Molnar
Education Associate, Virginia Living Museum
vlmed@juno.com
jamolnar@juno.com
All questions are valid; all answers are tentative.