RE: Unenlagia and Sinornithosaurus

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

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> bh480@scn.org
>
> The ABC article about Sinornithosaurus
> (http://abcnews.go.com/sections/science/DailyNews/dinofeath
> ers990916.html) quotes Larry Martin, who claims (again!)
> the feather-like fibers are only subcutaneous connective
> tissue. He says he wants to see fossils of lizards and
> other critters from Liaoning in case they show
> similar "feathers"--proving that the halos are not
> external integument. It is my understanding, though, that
> the Chinese have found fossils of lizards and other small
> beasties from Liaoning that do NOT show a halo of feather-
> like integument.


Indeed.  However, Martin could (properly) argue that absence of evidence is
not evidence of absence.

I do like Martin's alternative, in so far as it is *testable* (something
that seems to be outside the realm of most of the anti-dinosaurian origin of
birds studies).  IF we do discover turtles or crocs or lizards or frogs with
these structures on them, then we would seriously have to re-evaluate their
identification.

However, until such time, and given additional work (some published, some
not yet) on their finer structure, and given that they occur (so far) only
on theropods, the hypothesis that they are in fact feathers/feather
homologues is the best in town.

                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