RE: Yixian Forgeries

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

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Josh Smith
>
[concerning the use of the Yixian "rhamphorhynchoid" in biostratigraphy]
>
>     Hey wait a minute though...what is wrong with using a single
> specimen of a poorly studied taxon that is presumed to be
> phylogenetically similar to a Jurassic taxon that is also known only
> from within the very unit in question as a biostratigraphic age datum
> proving a Jurassic age?
>
> I seem to remember that is what they taught in Amherst.  Isn't that what
> they taught you at Hopkins?

Nah, I worked mostly with invertebrate paleontologists there: they are used
to working with sample sizes equal to or greater than 1... :-)

Now, in defense (!?) of the Yixian "rhamphorhynchoid", it may have some
derived features linking it to _Rhamphorhynchus_ not found in other basal
pterosaurs nor in Pterodactyloidea: I don't have the article handy.  If so,
then that the tagging on of a dromaeosaur tail doesn't modify the
phylogenetic affinity of the critter.  (By analogy, putting the fangs of a
_Thylacosmilus_ (the sabre-toothed marsupial of South America) in the jaws
of a partial skeleton of _Smilodon_ (a true sabrecat) would be wrong, but
the skeletal evidence of the _Smilodon_ would still accurately reflect its
feline affinities).

                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): 301-314-7843