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Re: Herbivore protection



At 11:55 AM 5/27/97 -0400, Carolyn wrote:
>
>Not to jump in too precipitously, but is it possible that hadrosaurs simply,
>to put it delicately, bred like bunnies?

Personally, I think you're right on the money (bunny money?) here.

As a group, I think the ability to breed in vast numbers was an important
factor in the ecology of both herbivorous and carnivorous dinosaurs.  There
is no strong evidence that hadrosaurids had some sort of special defense:
they were animals, not Street Fighter II characters.  As a threatened
individual, I have no doubt that they used sheer bulk, kicked with their
legs, hit with their arms, pushed with their bodies and tails, ran all out,
hooted and hollered (thereby alerting the rest of the herd), and did
whatever else they could to get away from a marauding tyrannosaur.

And many times, I'm sure they did get away (we have evidence, for example,
in the Denver Museum specimen).  Kill ratios of modern predators (i.e.,
number of kills/number of attacks) are nowhere near 100%, and (much as I
like tyrannosaurids), I do not expect nonavian theropods were any better.
Indeed, with their greater reproductive capability than large mammals, it
might have been possible for herbivorous dinosaurs to survive a higher level
of culling than would modern ungulates.  However, we do not have evidence of
this.

This is not to discourage people from suggesting novel methods of escape or
defense for various herbivores.  However, you should consider the
possibility that perhaps they did not have special abilities with regards to
defense, beyond the buddy system (i.e., when the attacking tyrannosaur shows
up, let him eat your buddy).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661