Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)

[dinoboygraphics@aol.com]

In response to Jamie's list of assumptions I wanted to point out a 
couple things:

> > > 2. Felids and falconids use their claws to grip, primarily, rather 
than cut.
The bulk of the claw is used to pierce and hold prey, and cannot be 
used to
slice (given the lack of a cutting ventral edge). <<<

I did not refer to falconid claws in that context (or the quote), 
rather I specifically referred to "the cutting edge of raptorial bird 
beaks" because in fact the cutting edge does not work without the 
keratinous sheath.  I did mention felid claws, specifically because 1) 
despite their lack of similar specializations cats routinely manage to 
or at least gash quite effectively, to the point of dissemboweling prey 
(as has been suggested for dromaeosaurs), and 2) their bony cores would 
not be able to do so in an experiment similar to the one Manning et al 
carried out with the Deinonychus claw core

I intentionally did not mention mention raptorial (avian raptors, that 
is) claws because they are specialized for puncturing and holding prey, 
and their resulting cross-section is nothing like the sickle-claws of 
deinonychosaurs.  Allosaur manual claws have more in common 
cross-sectionally with the pedal claws of falcons and their kin.

> > > 3. Regardless of the ventral constriction of dromaeosaurid unguals, 
the
unguals lack a sharpened edge. The conclusion that the keratin sheath 
should
follow and develop on the shape of the underlying ungual is likely, but 
to
exagerrate the shape is based on a previous assumption of function.<<<

That's my point, the claws are not merely laterally compressed, they 
are in fact forming an edge (at least in Deinonychus and Velociraptor), 
although not one that will cut through flesh without the sheath (and 
again, try shearing through meat with an eagle skull that lacks the 
ramphotheca).  It's worth noting that felid and falconiform claws are 
very different from each other.  While there's a decent bit of 
variation (especially with cheetahs) in general felid claws are more 
laterally compressed than falcon claws, so it's no suprise that felids 
more frequently use their claws to inflict slashing wounds.

Cheers,

Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333

www.skeletaldrawing.com