570 vanished lives

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.

250Cenozoic

Its estimated wingspan exceeded six meters, while bony pseudoteeth lined a beak adapted to slippery marine prey.

291Cenozoic

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

292Cenozoic

This giant flightless bird had a massive beak, but evidence favors a mainly herbivorous diet.

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.

299Cenozoic

Thick hide reinforced by tiny bony nodules protected this large ground sloth.

300Cenozoic

Huge curved claws belonged to a forest browser whose name is tied to Thomas Jefferson.

319Cenozoic

Schools of herring-like fish were sealed into fine lake sediments.

335Cenozoic

A large soaring bird with an estimated 11–12 ft wingspan; its diet involved more than a simple vulture comparison.

337Cenozoic

A strong flyer belonged near lineages whose living members are mostly flightless.

341Cenozoic

Deep jaws and slicing teeth suggest an ancient kangaroo relative that ate meat.

342Cenozoic

A bear-like carnivore used powerful jaws to pry and crush shellfish.

343Cenozoic

Long limbs converged on cheetah proportions, but its closest ties were to cougars.

344Cenozoic

Grasping feet and flexible shoulders reveal a large climbing marsupial.

358Cenozoic

Its wedge-shaped skull belonged to an ancient amphibian lineage separate from frogs and salamanders.

378Cenozoic

Its skeleton was once mistaken for a human killed in the biblical flood.