More on raptors...

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

At 09:31 PM 8/13/97 -0400, Amado Narvaez wrote:

>Since the root word "-raptor-" is also used in the clade Maniraptora,
>does that not establish a relationship between otherwise unrelated forms?
>Granted, "sickle-claws" are characteristic of Dromaeosauridae but not
>Tyrannosauridae. Granted, too, that when most people hear or use the term
>"raptor" the first thing that comes to mind is a sickle claw. But
>cladistically speaking, Maniraptora encompasses a wide range of diverse
>theropods with and without sickle claws, doesn't it?

Actually, the sickle claws of dromaeosaurids is very much unlike the
raptorial claws of modern "raptors" (falconiforms and relatives).
Dromaeosaurid sickle claws and hand claws are highly curved, with a very
flat (blade-like) cross-section.  True "raptor" (bird) talons are moderately
to highly curved, but have a thicker cross-section.

Morphometrically, the claws among nonavian dinosaurs most similar to eagle
talons are the manual claws of "megalosaurs", carnosaurs, and basal
tetanurines (such as the aptly named Dryptosaurus aquilunguis [=eagle
taloned wounding lizard]).  These dinosaurs have similar curvatures and
cross-sections, and probably used their claws in a similar fashion (to
pierce and pin their prey, rather than to slice them open).

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