[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: So-called Sickle Claws

Cat claws don't cut like razor blades; they pierce and tear and make nasty
wounds, but they don't slice like razors.  At least, not cats I've known. 
Maybe wild cats are different?  But they do have pads and other features to
elevate those toes.  As to what the keratinous covering on dromaeosaur
claws may have been, who knows?  Yes, the "sickle" claws are large, so are
the toes they are on and it seems like common sense those toes would be
weight-bearing like the others.  Can you imagine an animal with three big
toes walking on only two?  Ot jumping with their full body weight on big
prey and hanging there on only two out of six toes?  I don't have access to
real bonafide fossil material to look at, so I'm certainly going to defer
to those who do when it comes to such details as you site.  But I am
skeptical about pictures and drawings that may (or may not) be "enhanced"
or exaggerated as many fossils and mounts are.
> From: Thomas R. Holtz, Jr. <th81@umail.umd.edu>
> To: dinosaur@usc.edu; vonrex@gte.net
> Subject: Re: So-called Sickle Claws
> Date: Thursday, August 21, 1997 11:17 AM
> At 09:37 AM 8/21/97 -0700, <vonrex@gte.net> wrote:
> >Speaking, and I am, of things to be objected to; the term "sickle claw"
> >a misnomer that should be discarded.  The claw may be crescent shaped
> >a sickle but a sickle has a cutting edge along one side like a razor,
> >central to its very function.  "Raptor" claws have sharp tips for
> >and grasping, not slicing like a knife or razor.
> In terms of morphometrics, there are no theropod claws more highly curved
> nor flat side-to-side as dromaeosaurid second toe claws, especially
> _Deinonychus_.  They are very blade-like in cross-section.  Some
> dromaeosaurid claws actually have a sharp ridge along the inside of the
> On top of this, the bone is not the true external surface.  These things
> were covered with keratinous sheaths, which may (or may not) have
> a sharp edge.
> The claws of dromaeosaurids are NOT morphometrically like those of modern
> "raptors" (falconiforms such as hawks, eagles, falcons).  Those claws
have a
> lower angle of curvature, and a more oval cross-section.  The nonavian
> theropod claws closest to eagle talons are the manual claws of
> _Dryptosaurus_, and the like: the true analogs to raptor-birds among the
> nonavians.
> The claws of dromaeosaurids are closest to those of big cats, which do
> slashing/slicing as well as piercing.
> >The
> >exaggeration of this "sickle" claw's size and importance, I restate, is
> >merely for publicity and to make the animals seem more spectacular.
> The claw of _Deinonychus_ is still pretty damn big compared to the rest
> the animal.
> Thomas R. Holtz, Jr.
> Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
> Dept. of Geology              Email:th81@umail.umd.edu
> University of Maryland        Phone:301-405-4084
> College Park, MD  20742       Fax:  301-314-9661