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Re: Tarbosaurus

One of the things that would influence preservation in a fluvial environment, that come to my mind is this:
Velocity - If river A has a higher velocity than river B, than River A can carry a greater load. This load could and would include animal remains. If river B was a braided stream, produced after a dry season, then you would get fewer animal remains from river B. Reason? River B, being braided and seasonal, would not have the capacity to carry large loads over extended distances. Therefore, if a tyranosaurid died and fell into river B, it would not be carried a great distance and deposited on a sandbar someplace. However, if a tyranosaurid died and fell into river A, a perenial, meandering stream, then the animal would be carried for a good distance until it (most likely) became stuck on a sandbar. Any other animals that died further upstream would also float downstream until they came to rest on a sandbar, possibly even the same sandbar as the first tyranosaurid. What does this tell us? That in a fossil environment, higher concentrations of animal remains would be found on sandbars formed by meandering rivers. How does this relate to Tarbosaur/Tyranosaur population differences? It tells us that one possible explaination for the greater number of tyranosaurid remains in asia is due to a different type of river system with a different velocity. Does this answer the question of juvenile/adult ratios? No. However, this does show that environmental factors can make a large difference in the preservation of essentialy similar animals in seemingly similar environments (rivers).
AIM: TarryAGoat

From: Alan Blake Coulson <abcoulso@unity.ncsu.edu>
Reply-To: abcoulso@unity.ncsu.edu
To: Dinogeorge@aol.com
CC: dinosaur@usc.edu
Subject: Re: Tarbosaurus
Date: Sat, 22 Jul 2000 18:30:09 -0400 (EDT)

Regardless, saying "oh, factors were probably the same on both
continents" is vague to the point of being utterly useless. I know this is
not a formal sedimentological forum, but throwing around such weak
assumptions is bad form, as such "top-of-the-head" assumptions  all too
readily get ingrained as being correct.

On Sat, 22 Jul 2000 Dinogeorge@aol.com wrote:

> In a message dated 7/22/00 2:16:34 PM EST, abcoulso@unity.ncsu.edu writes:
> << I won't pretend to have the answer to this question. However, I
> think it is better to leave the querry open-ended, and have a list of
> relevant factors compiled, rather than settle on a "quick 'n easy"
> conclusion that is based on such a plethora of simplifying assumptions
> that we are guaranteed to have erred. >>
> Not necessarily. Sometimes a simple explanation is also the right explanation.

Alan Blake Coulson
3938-C Marcom St
Raleigh NC 27606
PhD student at North Carolina State University

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