Re: "PACK-HUNTING" THEROPODS

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 09:55 PM 3/26/98 -0500, Brian wrote:

>3) Slashing claws...
>The "killer claw" of _Deinonychus_ is *rounded* on its underside, hardly a
>shape conducive to the "razor edge" of the purported "killer claw", since
>the keratin would conform to the shape of the bone.

Not entirely true.  In predator (and other claws), the keratin sheath is not
always an exact duplicate of the ungual.  Felid claws often have two carinae
on the sheath, whereas there is only one on the ungual.  Ungual shape is
useful as a proxy of overall dimensions, but unfortunately there isn't a 1:1
correspondence with the details.

Incidentally, some dromaeosaurids from the Late K of the southwest,
currently unnamed, DO have quite a carina on the flexor surface.

>In fact, it resembles
>nothing so much as a raptor claw, and was just-as-likely used in the same
>manner, to hold down prey while the prey was being dispatched.

Morphometrically, no.  Dromaeosaurid claws have comparable angles of
curvature to raptorial bird claws, but are much deeper dorsoventally
compared to mediolateral dimensions than hawks, eagles, or owls.  Allosaur,
dryptosaur, and other "generic" tetanurine manual claws are the closest
match to bird claws in terms of angle of curvature & cross-sectional anatomy.

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