Introduction to the Cenozoic. University of California, Berkeley. Short description of the Cenozoic with links to more information about mammals (and the various subdivisions of mammals), birds, insects, and teleost fish, stratigraphy, fossils (ancient life), fossil localities, and tectonic changes in the Cenozoic.
The Cenozoic Era, the "Age of Mammals." Palaeos. Introduction to the Cenozoic with information on the geosphere (plate tectonics), climate, and biosphere (animals). If you scroll to the bottom of the page, there is an interactive time chart from which you can obtain information about different epochs.
Paleocene Mammals of the World. Martin Jehle. Good overview of the different groups of mammals that evolved in the Paleocene. Mostly text, with a few pictures.
Evidence for a Paleocene Radiation of Mammals. John Alroy, Smithsonian Institution. Online version of technical article explaining evidence for rapid diversification of mammals after the K-T mass extinction.
K/T Extinction. Paleomap Project. Map of the world 66 million years ago at the end of the Mesozoic and beginning of the Cenozoic Eras.