Re: Numbers of Dinos???

[Peter Sheehan <sheehan@csd4.csd.uwm.edu>]

On Wed, 30 Nov 1994, Stan Friesen wrote:

> From: sugarman@cerf.net
>  > 
>  > Does anyone have an idea how many T-Rexes there were?  Are we looking at a 
> population of a few or 
>  > are we looking at a situation where there were literally hundreds of 
> thousands scattered everywhere?
>  > Were dinos common?  
> 
> Hundreds of thousands alive at one time is *extremely* rare.
> Most uncommon animals have populations in the low millions.
> 
> As to actual numbers, no we really don't know.  However, based
> on specimen counts, T. rex was rather uncommon (about a dozen
> specimens, not counting teeth).  On the other hand, Triceratops
> was *very* common, with over thirty skulls, and many more individual
> bones.  Edmontosaurus and Anatotitan have similar specimen counts.
> 
> This is pretty much what is expected, the herbivores are common,
> the large carnivores are relatively uncommon.
> 
> The large numbers of the large heribvores suggests an actual
> abundance approaching that of the American bison, or the East
> African antelope.  If so, then T. rex may have been about as
> common as lion or hyaena packs (perhaps one T. rex in area that
> would sustain a single pride of lions)
> 
> This adds up to alot of individuals.  The species ranged at
> least from central Alberta to northern Utah, and from the edge
> of the Rockies east past the Black Hills.  This is a great many
> square miles.  [T. rex *may* have ranged as far north as the
> northern Alaska, and as far south as the Mexican border, but
> that is based on fragmentary specimens, and is uncertain].
> 
> 
> Based on certain assumptions, I once estimated that the total
> number of Triceratops that ever lived (over the whole several
> million years of their existance) exceeded a trillion individuals.
> [This gives you an idea of the sampling rate: some 50 to 100
> individuals out of a couple trillion].
> 
> swf@elsegundoca.ncr.com               sarima@netcom.com
> 
> The peace of God be with you.
> 
 
In the Hell Creek we found that about 4 per cent of dinosaur individuals 
were tyrannosaurids.

Peter Sheehan