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RE: tooth question




        -----Original Message-----
        From:   Thomas R. Holtz, Jr. [SMTP:th81@umail.umd.edu]
        Sent:   Wednesday, January 27, 1999 7:54 AM
        To:     Dwight.Stewart@VLSI.com
        Cc:     dinosaur@usc.edu
        Subject:        RE: tooth question


        Well, the evidence seems to be coming in from many dinosaur lineages
        (hadrosaurids, troodontids, sauropods, etc.) that a period of fast
growth
        was followed by a big slow down. (Dryosaurs, for some reason, have
different
        style bone growth).  The data look pretty good to me.  However,
beware of
        "ageing" of dinosaur individuals done in the 1980s and early-to-mid
1990s:
        as has been shown by recent work by Horner and others, the old "1
LAG = 1
        growth year" paradigm doesn't seem to hold, as different bones in
the same
        individual have different numbers of LAGs!

        I have to say that no one, to my knowledge, has published any growth
rate
        studies for T. rex (the only small T. rex postcranium known is the
type of
        "A. megagracilis").  Such a study would be feasible for T. bataar or
        Gorgosaurus libratus, but at present nobodies done that work.
However,
        based on the widespread presence of this pattern among dinosaurs, I
wouldn't
        be surprised if it held for tyrants as well. 

        Thomas R. Holtz, Jr.
        Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
        Dept. of Geology              Email:tholtz@geol.umd.edu
        University of Maryland        Phone:301-405-4084
        College Park, MD  20742       Fax:  301-314-9661

        @@@@@@@@@@@@@@@@@@@@@@@@@@@@

        Much thanks! :-)  Something that occurred to me when I was reading
"The Complete T. rex" was this: if this variation in growth rate did happen,
        one practical advantage could be a reduced effective basal
metabolism,
        thus (perhaps) requiring less food?

        Dwight