RE: Horner on NBC Nightly News

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

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Chris Collinson
>
>
> I really can't understand why Horner is so stubborn not to
> believe T-rex was
> a predator. The leg proportions are exactly that of a scaled up
> ornithomisaur, so it could run quite fast. It had the
> biomechanics of a bird
> not an elephant and so had pneaumatitized bone making the beast
> much lighter
> and nimbler, than would be expected for such a large animal. Due to its
> nimbleness it could likely take a fall with the best of them! The only
> arguably valid point that Horner makes is T-rex's specialized
> bone crushing
> jaws, analogous to modern day scavengers the hyenas. However, hyenas have
> Leopards, Lions, Cheetahs, Cape dogs and Jackals to steal from (not to
> mention the fact that Hyenas often hunt for them selves anyway).

Actually, in point of fact, some populations of the spotted hyena are
actually primarily hunters rather than scavengers.  If it weren't for the
direct field observations of the Kruuk's, however, this would not be known:
one of the problems with paleo is that we can't send field researchers out
to watch and directly document our critters' behaviors.  (Or if we did, it
would be pretty boring: "Day 15: tyrannosaur specimen HP-117 remains
immobile.  _Edmontosaurus_ specimens HP-113 and 117 apparently unaware of
close proximity of tyrannosaur, although this may be due to the fact that
these specimens are a tail and a right hindlimb, respectively...")

DinoGeorge points out:

> You might consider the possibility that Tyrannosaurus occupied different
> niches at different times in its life. Perhaps it was a predator
> while young
> and relatively small, then became a scavenger when older and huge.

Quite so!  This is mentioned in my paper in the
possibly-never-to-be-published DinoFest 98 volume, as are other
possibilities (for example, the ratio of scavenged vs. hunted food might
vary with seasons, or within species from region to region, or within
species from stratigraphic interval to stratigraphic interval, or among the
various tyrannosaur species).

                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