570 vanished lives

219Paleozoic

Long upper canines and a wide gape made it an early experiment in saber-toothed predation.

241Cenozoic

Tapir-sized and short-faced, it lived before proboscideans acquired the elephant's long trunk and giant body.

242Cenozoic

A widened jaw and flattened lower tusks formed a shovel-like cutting edge for tough vegetation.

243Cenozoic

Only the lower jaw carried tusks, curving downward beneath a body taller than most modern elephants.

244Cenozoic

Two upper and two lower tusks gave its elongated head a four-tusked profile absent from living elephants.

245Cenozoic

Hyaenodon horridus was a meat-eating hyaenodont mammal, not a hyena; its large skull can inflate skull-length mass estimates.

246Cenozoic

A bear-heavy torso combined with a dog-like long skull and tail, inspiring the name bear-dog.

247Cenozoic

A giant hyaenodont with a skull about 66 cm long. Body-mass estimates are uncertain, and it was neither a hyena nor a big cat.

248Cenozoic

A sloth lineage with aquatic adaptations, including dense bones that could help control buoyancy.

249Cenozoic

It may have approached a tonne, with giant incisors capable of generating exceptional bite forces.

261Paleozoic

Its long skull and deep tail suggest a waterside animal that was still a capable walker.

262Paleozoic

Low vertebral ridges accompanied a deep skull and strongly differentiated teeth.

263Paleozoic

A light build, long limbs and small skull bosses combine primitive and therapsid features.

264Paleozoic

A huge skull combined thickened impact surfaces with long canines in a formidable predator.

265Paleozoic

A domed, massively thick skull crowned the barrel body of this giant herbivore.

266Mesozoic

A small Early Triassic cynodont with differentiated teeth, known from skeletons curled inside fossil burrows in South Africa.

267Mesozoic

A dog-like snout, slicing cheek teeth and upright hind limbs made it a major cynodont predator.

291Cenozoic

Long hind legs and a balancing tail powered a distinctive hopping gait through the forest floor.

293Cenozoic

Hoof-like toes and a large predatory skull belonged to a carnivorous mammal with no modern equivalent.

294Cenozoic

An early whale with four weight-bearing legs: Pakicetus attocki was wolf-sized and lived near rivers in Pakistan about 50 million years ago.

295Cenozoic

A streamlined whale body still carried tiny external hind limbs with no walking function.

296Cenozoic

A broad hollow nasal ram rose from the skull of this immense brontothere.

297Cenozoic

A forked Y-shaped nasal horn joined two brow horns in the most elaborate protoceratid display.

298Cenozoic

Short legs and a barrel body gave this grazing rhinoceros a hippo-like outline.