RE: Tyrannosaurid character states

-----Original Message-----
From: calzola [mailto:calzola@iol.it]

>Hi all,

>I may have sent this directly to Dr. Holtz, but thought it may be of some interest to other members as well.

>

>I've just read HP Holtz's paper on Tyrants' Phylogeny and Taxonomy in "Mesozoic Vertebrate Life" and have some

>questions(not necessarily directed to the author... answer freely if you feel).I apologyze if questions like these have already

>been answered in the past or if they're of obvious answer.

>

>1)What do the "-"s in front of some character (as listed in appendix 7.3) mean? (e.g. -83.0 )

It is a minus sign, representing a reversal (to the primitive condition).

>2)The Kirtland shale aublyosodontine

Which, incidentally, is probably not an "aublysodontine", but a Daspletosaurus-grade tyrannosaur!

>is said to show the condition .2 for character n° 59, but in the character list there's

>no such state. Should it be 59.1 or is the 3rd condition for character 59 missing in the character list?

That is a typographical error in Appendix 7.3. If you consult the actual data matrix, it is listed as "1".

>3) Could someone enlighten me on character 106 states? just can't visualize them....

Okay, look at a tyrannosaurid snout face on. In typical tyrannosaurids (or other theropods), the dorsalmost tips of the narial processes of the premaxillae are not in contact: instead, a slip of the nasals separates them. In T. rex, however, the tips of the narial processes are in contact all the way up. If you have access to Thom Carr's 1999 tyrannosaurid facial ontogeny paper in JVP, check out fig. 5 for the primitive condition, then fig. 8I, J for the derived (where it is, in fact, labeled "1").

                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