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Re: Rearranging the branches of the Tree of Life...



> I think the "third possibility" referred to was that sponges lost the
> tissues in a reversal and used to be more complex.
>

A major problem with this study is the undersampling of taxa at the base
of Metazoa. For example, it does not use at least one hexactinellid (glass
sponge), one demosponge (common sponge), and one calcarean (calcareous
sponge). Other studies that incorporate all of these have shown that
"Porifera" is almost certainly paraphyletic, with some sponges closer to
eumetazaons (you, me, and corals) than they are to other sponges.

It isn't that it tested that possibility and failed to recover it; it is
that it is incapable of testing those hypotheses at all.

Just one of the sampling problems with the analysis. There is a lot of
good material in the paper, but to consider the matter "settled" as per
the press release is ridiculous in the extreme!

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Fax: 301-405-0796

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA