The Cenozoic Era, which is often described as the “Age of Mammals,” began 65 million years ago. Following the disappearance of the dinosaurs, mammals proliferated in number, size, and diversity. The Cenozoic is generally divided into seven epochs: Paleocene, Eocene, Oligocene, Miocene, Pleistocene, and Holocene.
Shown below are the Cenozoic displays in the Raymond M. Alf Museum of Paleontology on the campus of the The Webb Schools, a private residential high school, in Claremont, California.
According to the Museum display:
“Mammals and birds will steal the limelight from the dinosaurs of the Mesozoic. Numerous mountain ranges will emerge, including the Rocky Mountains and Himalayas. Grasses and other flowering plants will flourish. And, the earliest modern humans will evolve during the time known as the Ice Ages.”
Shown above: (1) dragonfly; (2) waterbug; and (3) fish with smaller fish in its mouth. All of these are from 50 million years ago.
Shown above is a palm frond and a perch from 50 million years ago.
Shown above is a Poebrotherium skull from 35 million years ago. This was an early camel.
Shown above is a Mesohippus skull from 35 million years ago. This was an early horse.
Shown above is a Hyracodon skull from 35 million years ago.
Shown above is a Trigonias skull from 35 million years ago. This was an early rhino.
Shown above is an Archaeotherium skull from 35 million years ago.
Shown above is Protolabis barstowensis, a camel from 15 million years ago. This animal was 7 feet long, stood 5 feet high at the shoulder, and weighed 300 pounds.
Shown above are a mammoth tooth (center left), a mastodon tooth (center right), a mastodon tusk (bottom), smilodon (saber-tooth cat), and Arctodus skull.
Shown above is another view of the saber-tooth cat skull.
Shown above is another view of the Arctodus skull. This is the short-faced bear.
Shown above is Purussaurus brasiliensis, a giant alligator from 7 million years ago. This animal was 40 feet long and weighed 10-12 tons.
Another view of the giant alligator.
Shown above are grassland animals: (1) Hypohippus skull palate; (2) Scaphohippus jaw; and (3) tortoise shell. All of these are from 15 million years ago.
According to the Museum display:
“The great patchy forests of North America gave way to vast grasslands during the Miocene. This is reflected in two types of horses found at Barstow. One was very abundant. It had high-crowned teeth and fed mainly on grass. The other type of horse had low-crowned teeth and fed mainly on brush (browser). Browsing horses at Barstow soon became extinct, while the grazing types flourished.”