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MIgration, Still



Hello All,

If we examine the case of a mass bonebed, like what Horner found for
example, just what can be gleaned from the site? I can't think of any good
reason for that  mass of bodies to be fossilized unless they died in
migration, and wound up at their final resting place by the action of a
flowing stream. Where they  so stupid that they walked into a raging river
for no good reason? Doesn't the logical conclusion point toward some force
of nature, either external or no, that drove these beasts into a dangerous
situation that killed a pile of them at once.

What leads me to think they all fell victim at once is the jumbling of the
bones.

There exsits a similar bone bed near where we work the upper hell creek, in
SD.  Arcadia (sp?) college is working that site, and it is a huge mass of
bones. From what we have been told the bones are at all angles to each
other. We haven't visited in the 3 years I've been going out there, 'cause
we're too damned busy with our own fossils, but I intend to.

I suppose a really big flash flood could sweep a valley clean, and get
everything overbank, including the local population of Edmontosaurs. A
lahar (sp?) could also do it, I suppose.  A prior die-off leaving bloated
carcases lying aroud waiting for a flood to carry them away might acount
for it. The chances that they all wandered into a bog just doesn't seem to
fit. Why would one species be focused, or favored, and not a mixing of many
species? I don't think the sinkhole idea will translate to this situation,
nor would a quicksand pit.

In what way could the reading of the field data from such a site help to
determine the facts in this whole scenario? The stratigraphic data could be
more important than the fossils in determining the conditions of
deposition, but how could one establish the time frame, or estimate the
energy of the deposition? Would correalating the stratigraphic data and
depositional impact on the bones be linkable, and if so what sholud be
looked for? I mean beyond the obvious signs Horner cited, but more subtle
evidence.

This may seem a bit elementry to may of you, but I'm struggling for a way
to resolve this question of migration in my own little mind. I don't care
if dinosaurs migrated one way or the other (aaargh), except if they did it
might be a  predictable way to find fossils. If even a local migration
pattern could be proven the locating of such bonebeds might become much
easier. If a continental migration route could be established it just might
give us the broadest understanding of the paleoecology at the end of the
Cretaceous to date. I'm not saying I'll contribute anything like that, just
musing. However sometimes us amatuers hit one from "downtown".

Roger A. Stephenson
Hell Creek Homey