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RE: taphonomy (was Re: Tarbosaurus?)




> -----Original Message-----
> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Dann Pigdon
> Sent: Monday, July 24, 2000 10:57 PM
> To: dinosaur@usc.edu
> Subject: taphonomy (was Re: Tarbosaurus?)
>
>
> Alan Blake Coulson wrote:
>
> > " Show me how the speed or depth of the water"
> >
> >         faster water can move larger skeletal elements, and move smaller
> > elements more readily. Thus, faster water = smaller elements
> are harder to
> > preserve in situ, or at all, as they're abraded during transport.
>
> I've studied the effects of fluvial activity on objects at length, so at
> last I'm qualified to say something useful! Most of the references I'm
> familiar with deal with stone, but the same general principles should
> apply to bone as well.
>
> Faster water does have the potential to move larger elements, although
> this will very much depend on the shape of the elements in question.
> Elongated bones will be moved more readily than those with a smaller
> surface area:volume ratio (ie. those that are rounder). Also, although
> fast water can completely remove smaller elements in some instances, in
> others it can actually help deposit sediment over them and thus preserve
> their positions. Larger elements that stick out of the deposited
> sediments may be moved or abraded more easily than smaller elements that
> were completely covered. Of course if you're talking extremely fast
> water there may be no deposition at all, and everything can end up being
> swept away.

[snip]

I might add that these various aspects result in different sorts of bones
(skulls vs. limb bones vs. pelves) in sorting out in different fluvial
regimes.  Voorhies did some classic taphonomic studies back on this starting
in 1969.

A ref. for people, old but still good, is:
Behrensmeyer, A.K. & A.P. Hill (eds).  1980.  Fossils in the making:
vertebrate taphonomy and paleoecology.  Univ. Chicago Press.

The papers therein cover many general aspects of vertebrate taphonomy, as
well as specifics (i.e., sorting out human vs. non-human influence on a
site) that we of a Mesozoic bent don't have to worry about...