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RE: Robust vs. Gracile

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Srnka, Christopher P.
> Sent: Friday, July 20, 2001 3:39 PM
> To: 'dinosaur@usc.edu'
> Subject: Robust vs. Gracile
>
>
> What characteristics determine whether a specimen is considered robust or
> gracile? Is it general build, bone density, comparative size to other
> specimens?
>
Robust vs. Gracile are relative terms, generally of bone proportions (i.e.,
thickness relative to length).  For example, within a single population of
organisms (say, _Coelophysis bauri_) you might have forms with thicker
femora than others of the same femur length.  Or, in cross taxon comparison,
you can have robust hominins (like _Paranthropus_) whose limb or jaw bones
are thicker than those of more gracile forms.

However, being relative terms, they are context related.  Even the most
robust _Paranthropus_ is very gracile compared to (say) a glyptodont, and
even the most gracile _Australopithecus_ is very robust compared to a
gazelle!

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796