Such instances are by no means singular, nor are like difficulties confined to the eocene.
"The Old Riddle and the Newest Answer"
John Gerard
Far back in geological times the tapir-like Moeritherium, which wandered through eocene swamps, had within itself the prophecy of two diverse lines.
"Edge of the Jungle"
William Beebe
Traces of glacial conditions have also been met with in the eocene and Miocene.
"Geology"
James Geikie