This is not very shell-related, though perhaps you could tie in horse
conchs, horse mussels, Cheilea equestris, or Hipponyx.

No modern horses occur with the Eocene five-toed horses.  The Eocene forms
occur in both Eurasia and North America, with either Siberia to Alaska or
north Europe to Greenland to Labrador as possible routes of interchange.
(Incidentally, marine mollusks provide an important method of determining
when the marine passages were open and what direction the currents
travelled).  Horses were rather common in North America up through about
10,000 years ago, which coincides with both the last glacial retreat and
the spread of humans in North America.  As the horses survived all the
previous glacial retreats, I think the humans are more likely to blame.
Equus caballus, the domestic horse, was then introduced by Europeans.  As
grazers, horses have very durable teeth, so this might contribute to their
abundance in the fossil record.

Thanks to all for the congratulations!



Dr. David Campbell

"Old Seashells"

Department of Geological Sciences
CB 3315 Mitchell Hall
University of North Carolina at Chapel Hill
Chapel Hill NC 27599-3315
USA

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919-962-0685
FAX 919-966-4519

"He had discovered an unknown bivalve, forming a new genus"-E. A. Poe, The
Gold Bug