Paleogene is a geologic period that spans 46 million years.
During the Paleogene, mammals diversified from relatively small, simple forms into a large group of diverse animals in the wake of the CretaceousPaleogene extinction event that ended the preceding Cretaceous Period
 == See also ==CretaceousPaleogene boundary  Geological formation between time periods== References ==== External links ==Paleogene Microfossils: 180+ images of ForaminiferaPaleogene (chronostratigraphy scale)

