[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: The validity of cladograms (was Re: giant birds)

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Dinogeorge@aol.com
> << Are they "different" 90 % of the time?  Tom "Captain Clade" Holtz
>  presented a good poster at SVP this year showing that, statistically,
>  the "different" theropod trees out there aren't so "different" after all
>  - certain select groups are bouncing around in different analyses, but
>  the general pattern is stable and uniform. >>
> I wonder how much of the stability arises from everybody using everybody
> else's character matrices, rather than from a genuine phyletic
> signal. Might
> be interesting to see what happens if one uses only skull
> characters in one
> analysis versus only postcranial characters in another analysis.

This is a perfectly acceptable sort of test: would like to see the results
if anyone runs it! (Students looking for research paper topics in paleo
classes, take heed!!).

(Incidentally, one of the nice aspects of phylogenetic analysis is that one
IS able to incoprorate previous work into your own.  By verifying/checking
previous observations, and making new ones of your own, you are able to test
congruence of character against character).

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-314-7843