Except where noted, all images provided by Angelfire

Andrewsarchus (Mesonychid)

Late Eocene-Oligocene

Basilosaurus cetoides

Eocene

Diatryma (early flightless bird)

Eocene

Entelodont

Eocene-Oligocene

Mammuthus primigenius (Whooly Mammoth)

Pleistocene

Megacerops

Oligocene

Megatherium (giant ground sloth)

Pliocene-Pleistocene

Smilodon (sabre-tooth tiger)

Pleistocene

Synthetoceras

Oligocene-Pliocene

Uintathere

Eocene-Oligocene