Chew on this: Study of ancient teeth bites theory of early primate disappearance

Fifty-six million years ago, just before earth’s carbon dioxide levels and average temperatures soared, many species of primitive primates went extinct in North America for reasons unclear to scientists. Now, a study of fossilized molars appears to exonerate one potential culprit in the animals’ demise: competition with primitive rodents for food.
Paleontology News — ScienceDaily