Skip to main content

In Images: 'Field Guide' Showcases Bizarre and Magnificent Prehistoric Mammals

Ground sloth

prehistoric mammals

(Image credit: Mary Persis Williams)

"The Princeton Field Guide to Prehistoric Mammals" introduces readers to many charismatic and bizarre mammals from the distant past, offering a glimpse of the peculiar forms that preceded mammals alive today.

Swimming ground sloth Thalassoconus lived in what is now Peru and Chile during the late Miocene epoch, from about 12 million to 5 million years ago.

Deinotherium

prehistoric mammals

(Image credit: Nobumichi Tamura)

Deinotherium lived during the Oligocene epoch, 34 million to 23 million years ago. It was bigger and had longer legs than the modern elephants it resembles, and had lower tusks that curled down and backward, toward its body.

Sea cow

prehistoric mammals

(Image credit: Mary Persis Williams)

The extinct giant Steller's sea cow, Hydrodamalis gigas, was described in the mid-18th century, and was as big as some whales — up to 30 feet (9 meters) in length.

Carpolestes

prehistoric mammals

(Image credit: Doug Boyer)

Tarsier-like Carpolestes was a primate relative from the Paleocene epoch, 66 million to 55 million years ago. It had grasping hands like a primate, and lived in trees, as do many modern primates.

Nuralagus rex

prehistoric mammals

(Image credit: Mary Persis Williams)

A modern rabbit is dwarfed by Nuralagus rex. This gigantic rabbit lived during the Pliocene epoch, 5 million to 2.6 million years ago, on the island of Minorca, in the Mediterranean Sea off the coast of Spain.

Chasmoporthetes

prehistoric mammals

(Image credit: H. Galiano)

A reconstruction of Chasmoporthetes, a hyena with long legs for running. It lived in Eurasia and North America during the Pliocene (5 million to 2.6 million years ago) and Pleistocene (2.6 million years ago until 10,000 years ago) epochs.

Enhydriodon dikikae

prehistoric mammals

(Image credit: Mary Persis Williams)

East Africa's enormous "bear otter," Enhydriodon dikikae, lived alongside our earliest ancestors in Ethiopia during the Pliocene epoch, 5 million to 2.6 million years ago.

Trogosus

prehistoric mammals

(Image credit: Mary Persis Williams)

Trogosus belonged to an order of extinct mammals known as the tillodonts, which inhabited North America, Asia and Europe during the Paleocene (66 million to 55 million years ago) and Eocene (55 million to 34 million years ago) epochs. Tillodonts had powerful jaws and short, small braincases.

Morgancudon

prehistoric mammals

(Image credit: FunkMunk/Wikipedia Commons)

Shrew-size Morganucodon was one of the first true mammals, emerging during the Late Triassic period (201.3 million to 235 million years ago). They had large brains and tiny teeth for grinding up insects, much like the teeth of living insectivorous mammals.

Volaticotherium

prehistoric mammals

(Image credit: Mary Persis Williams)

Volaticotherium had delicate limbs and a gliding membrane similar to those in modern flying squirrels or sugar gliders. It lived in Mongolia during the Jurassic period, 199.6 million to 145.5 million years ago.

Behemotops

prehistoric mammals

(Image credit: Mary Persis Williams)

Hippo-like Behemotops lived during the Late Oligocene, 28.4 million to 23 million years ago, inhabiting marine waters, brackish river mouths and lagoons, keeping close to the shore. It likely spent most of its time in the water and had eyes positioned at the top of its head so it could see while its body was fully immersed.