Tyrant taxonomy (was RE: Big Bakker article in June Discovery Mag)

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

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Tim Donovan
>
> Nick Pharris <npharris@umich.edu> wrote:
> Quoting MariusRomanus@aol.com:
>
> > I know that the Canadian theropods are albertosaurs (or has it now been
> > permanently changed to gorgosaurs)
>
> Two different animals, but yes, I think the well-known one has
> turned out to
> be _Gorgosaurus_.
>
>   Is it valid, and different from Daspletosaurus?
>
Turning on my validoscope on the genericometer, I get a reading of 7.92 (+/-
0.5), so it is valid... :-)

Okay, in reality, we can say that:
a) Many, although by no means all, paleontologists working with large
theropods consider _Gorgosaurus libratus_ to be distinct from _Albertosaurus
sarcophagus_.
b) Futhermore, everyone now (as far as I know) agrees that _Gorgosaurus
libratus_ (or _Albertosaurus libratus_, or the Judithian specimens of
_Albertosaurus sarcophagus_ if you really want to lump) is distinct from
_Daspletosaurus torosus_.

As an aside (and especially for newer folks on the list), there does not
exist such thing as a genericometer or as a fully agreed-upon metric for
telling whether a proposed species is "valid" or not.  Really.  Truly.

This is true for modern species as well as fossil ones.

                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