Initially, this work was designed to document and study the
diversification of modern mammalian groups and was quite successful and
satisfying. However, as field and laboratory work continued, there began
to develop a suspicion that not all of the Eocene story was being told.
It became apparent that most fossil samples, especially those from the
American West, were derived from similar preservational circumstances
and similar depositional settings. A program was initiated to look for
other potential sources of fossil samples, either from non-traditional
lithologies or from geographic areas that were not typically sampled. As
this program of research grew it began to demonstrate that different
lithologies and different geographic areas told different stories from
those that had been developed based on more typical faunal
assemblages.
This book is conceived as an introduction to non-traditional Eocene
fossils samples, and as a place to document and discuss features of
these fossil assemblages that are rare or that come from rarely
represented habitats.