RE: Serration variation

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

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Dinogeorge@aol.com
> Sent: Wednesday, February 09, 2000 7:48 PM
>
> In a message dated 2/9/00 7:35:38 PM EST, dbensen@gotnet.net writes:
<
> Neither behavior nor tooth shape has been shown to be independent of
> phylogeny. So who knows what "more" means in this context. Also,
> I don't know
> of any theropod group in which >lost< tooth serrations were
> >regained<. But
> there were surely theropods that evolved serrated teeth
> independently of one
> another, from smaller (birdlike) theropods that had tiny, unserrated
> teeth--the same kind as seen in Archaeopteryx.

One thing to be concerned with is developmental constraints: some authors
have suggested that  the constructional mechanisms required to place the
serrations on teeth may only operate after the tooth is a certain size.
Absence of serrations on very small teeth *might* thus be of developmental
rather than phylogenetic significance.

                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