RE: related to several threads

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Aegyptiacus@aol.com
>
> A. lithographica:I see there (with my little eyes) 2
> possibilities. Have all of the feathers of the skeletal specimens
> been identified clearly (I mean, rectrices, remiges, and so
> forth), at least as clearly as the lone feather? If not, it could
> be a kind of feather not well preserved on the specimens. If yes,
> couldn't it be sexual dimorphism, as observed in modern birds? If
> not again, it MUST be a different taxon.

Actually, no: there are yet more possibilities:
*Ontogenetic variation (after all, the feather IS smaller than the retrices
and remiges of the Archies with good feather impressions)
*Seasonal variation (although in modern avialians, such changes are
predominantly color-related)
*Taphonomic variation: the lone feather, after all, is preserved via
carbonization, while the others are through impressions. Furthermore, any
2-dimensional (or nearly 2-D) representation is a 3-D object suffers from
distortions; the same object might produce one of several different forms
when projected onto a 2-D surface.

Of course, all this is a moot point! If memory (and Dinogeorge's memory)
serves, ICZN Opinions #607 and #1070 (petitions by Swinton and Ostrom,
respectively) fixed the BMNH specimen as the holotype. (see
http://www.cmnh.org/dinoarch/1999Sep/msg00548.html)

                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