A Complete, A to Z List of Prehistoric Mammals
A long-snouted ancestor of the sperm whale.
This mammal wasn't far removed from its therapsid ancestors.
This "cat-toothed" dog behaved more like a hyena.
A giraffe-like camel of the Miocene epoch.
This primitive whale used both teeth and plankton-filtering baleen.
This African primate was discovered by Richard and Mary Leakey.
This ancestor of the Giant Panda lived over 10 million years ago.
One of the few prehistoric bears to have lived in Africa.
An early marsupial of the late Cretaceous.
This "walking whale" led an otter-like lifestyle.
This "shovel-toothed" elephant thrived in flooded lowlands.
American Cheetah (Miracinonyx)
It may actually have been a kind of puma.
American Lion (Panthera Leo Atrox)
The biggest lion ever to walk the earth.
Also known as the "Hagerman horse."
Otherwise known as the "Bear Dog."
This early elephant's tusks were as long as its entire body.
A long-lived "side branch" on the equine tree of life.
This large herbivore lived alongside our human ancestors.
The biggest terrestrial meat-eating mammal that ever lived.
A gorilla-sized lemur from Madagascar.
This ancient lemur only went extinct 1,000 years ago.
This early hominid was unusually mild-tempered.
A two-horned, rhino-like browser from Africa.
An elephant-like ungulate from South America.
Africa's only indigenous bear.
This giant bovine went extinct in the 17th century.
The immediate predecessor of genus Homo.
A pint-sized "sloth lemur" from Madagascar.
This dolphin once lived in the Yangtze River.
This Indonesian tiger went extinct 50 years ago.
An extinct lion of northern Africa.
The biggest of the "false" saber-toothed cats.
This ancient elephant sported eight short, stubby tusks.
The biggest prehistoric whale that ever lived.
Bison Latifrons (Giant Bison)
A Mammoth-sized bison of the late Pleistocene.
This antelope was hunted to extinction 200 years ago.
A large, hyena-like marsupial from South America.
One of the biggest of the bone-crushing canids.
The oldest "new world" monkey yet identified.
The biggest of the Eocene "thunder beasts."
Also known as the "biting sperm whale."
The last camel ever to live in North America.
A recently extinct lion of South Africa.
Caribbean Monk Seal
Christopher Columbus called it the "sea wolf."
A recently extinct tiger of central Asia.
This early mammal is known as the "Jurassic beaver."
Cave Bear (Ursus Spelaeus)
Guess where this prehistoric bear spent most of its time?
Cave Hyena (Crocuta Crocuta Spelaea)
This hyena competed with early humans for living space.
Cave Lion (Panthera Leo Spelaea)
The biggest lion that ever lived.
A sleek ancestor of the modern gray whale.
It looked like a cross between a horse and a gorilla.
This ancient mammal had a raccoon-like tail.
Did this tiny mammal feast on Troodon eggs?
The tiny ancestor of all modern-day carnivores.
One of the most common mammals of the early Eocene epoch.
Better known as the saber-toothed squirrel.
This early mammal had some squirrel-like characteristics.
One of the few prehistoric elephants to have lived in South America.
This was once thought to be the first true dog.
This prehistoric pig was the size of a rhinoceros.
Did this ancient primate lay at the root of human evolution?
A giant hedgehog of the Miocene epoch.
One of the largest mammals ever to roam the earth.
A strange, hippopotamus-like creature of the Miocene epoch.
An ancient ancestor of even-toed ungulates.
A Cretaceous ancestor of the modern opossum.
This leopard-like cat roamed the plains of North America.
This jaguar-sized cat may have preyed on early hominids.
This prehistoric horse wasn't quite as fearsome as its name.
Diprotodon (Giant Wombat)
This prehistoric wombat was the size of a rhinoceros.
Dire Wolf (Canis Dirus)
A giant wolf of the Pleistocene epoch.
Perhaps not a true mammal, but a "mammal-like reptile."
A gigantic, spike-tailed armadillo of the Pleistocene epoch.
This small whale was once mistaken for a baby Basilosaurus.
Guess where this "tree ape" spent most of its time?
This "foolish dog" went extinct in the 19th century.
This pint-sized proboscid went extinct 10,000 years ago.
This prehistoric rhino may have inspired the unicorn legend.
This "battering ram beast" had a bizarre head ornament.
This ancient pinniped pursued a wide variety of prey.
Entelodon (Killer Pig)
A giant pig of the Eocene epoch.
This giant mammal was closely related to Uintatherium.
This early mammal is known from a single, spectacular fossil.
This "dawn monkey" was only a few inches long.
This Triassic critter may (or may not) have been the first true mammal.
This prehistoric dog was built more like a big cat.
This tiny, prehistoric horse lived 30 million years ago.
Otherwise known as the Pan-American Ground Sloth.
This tiny burrower was ancestral to modern pangolins.
This prehistoric deer had a distinctive set of antlers.
The immediate predecessor of modern canines.
A prehistoric dolphin with a swordfish-like snout.
This big cat went extinct 1,000 years ago.
A three-foot-long, prehistoric anteater.
This cat's canines were almost as long as its entire skull.
The earliest digging mammal yet discovered.
Does it imply an Asian origin for anthropoids?
Giant Beaver (Castoroides)
This giant beaver weighed about 200 pounds.
Giant Ground Sloth (Megalonyx)
The bones of this giant sloth were discovered by Thomas Jefferson.
Giant Hyena (Pachycrocuta)
It was three times the size of a modern hyena.
Giant Short-Faced Bear (Arctodus Simus)
One of the largest bears that ever lived.
This "giant ape" was twice the size of modern gorillas.
This prehistoric sloth's bones have been found in the La Brea Tar Pits.
This armadillo was the size of a Volkswagen Beetle.
One of the earliest shovel-toothed elephants.
This tiny mammal had an unusually large brain.
Yet another ancient lemur from Madagascar.
A sheep-sized ancestor of the Giant Sloth.
This "half-dog" was more closely related to modern bears.
An early ancestor of the modern dog.
One of the most successful horses of the Miocene epoch.
This donkey-sized horse had a prominent snout.
The last specimen of this "scimitar cat" died 10,000 years ago.
This "armed murderer" leaped on its prey from high trees.
Horned Gopher (Ceratogaulus)
This two-horned gopher looked like a miniature rhinoceros.
This fearsome carnivore was the Eocene equivalent of a wolf.
This Miocene horse had unusually short legs.
An ancient ancestor of modern tapirs.
This ancient rhinoceros looked more like a horse.
The horse formerly known as Eohippus.
The earliest bat yet known from the fossil record.
One of the first ground-dwelling hyenas.
This ancient hoofed creature may (or may not) have been ancestral to whales.
The largest land mammal that ever lived.
Irish Elk (Megaloceros)
This prehistoric deer had dinosaur-sized antlers.
This prehistoric whale looked more like a dolphin.
A recently extinct tiger of Indonesia.
The earliest known placental mammal in the fossil record.
A long-tailed relative of the early whale Ambulocetus.
A small, jumping mammal of the Eocene epoch.
A tiny, foxlike ancestor of the modern dog.
A killer sperm whale of the Miocene epoch.
This early mammal had a transitional inner ear.
One of the earliest of the true sabre-toothed cats.
It looked like horse crossed with a camel crossed with an elephant.
This prehistoric whale gave birth on land.
Did this ancient whale suck up prey on the sea floor?
This early mammal was named after Mao Zhedong.
Its most famous species was the North American Mastodon.
This prehistoric lemur weighed over 100 pounds.
One of the most successful predators of the prehistoric plains.
Megatherium (Giant Sloth)
This prehistoric sloth was bigger than an elephant.
A transitional form between therapsids and true mammals.
One of the biggest carnivores of the Miocene epoch.
The first prehistoric rhino to evolve horns.
An important intermediate step in equine evolution.
A distant relative of modern camels.
This "middle horse" was about the size of a deer.
This wolf-like predator may have been ancestral to whales.
This Pliocene monkey resembled a modern macaque.
A sleeker relative of Dinofelis.
This rhinoceros looked more like a hippopotamus.
One of the oldest carnivorous mammals yet identified.
This "Miocene horse" actually lived much earlier.
This ancient elephant was about the size of a pig.
Another early mammal of the late Triassic period.
This "stupid-footed" mammal was a close relative of Chalicotherium.
This prehistoric sloth weighed "only" about 500 pounds.
Myotragus (Cave Goat)
Did this strange goat have a cold-blooded metabolism?
A big-eyed tarsier of the Eocene epoch.
It took over 100 years for this mammal to be identified.
This "island tooth" was a close relative of Toxodon.
A prehistoric cat with some hyena-like qualities.
This lemur-like primate lived 50 million years ago.
The biggest rabbit that ever lived.
This prehistoric platypus had a toothed bill.
An extremely mammal-like reptile of the early Jurassic.
One of the earliest bats in the fossil record.
Paleontologists call it the "cookie monster."
This prehistoric horse was a close relative of Hyracotherium.
This prehistoric ape was discovered in Greece.
This dog-like mammal was ancestral to modern whales.
This ancient beaver lived in deep burrows.
A prehistoric bat of Eocene Europe.
This "ancient rabbit" was the same size as its modern descendants.
One of the earliest elephant-like proboscids.
This "sloth lemur" looked like a cross between...
This tapir-like beast was remotely related to modern horses.
This "ancient puzzle" was a dead end in mammal evolution.
A close relative of the Giant Wombat.
This "almost horse" had noticeably enlarged middle toes.
A bigger, smarter version of Australopithecus.
Its name is Greek for "monstrous sheep."
A five-foot-long, two-horned armadillo.
One of the first hooved mammals to appear on earth.
An early ancestor of modern elephants.
The earliest known ancestor of modern elephants.
Was this the common ancestor of great apes and lesser apes?
A tiny--and strange--Australian marsupial.
This prehistoric elephant came equipped with its own spork.
An ancient ancestor of the modern peccary.
One of the earliest primates yet discovered.
This prehistoric horse was built for speed.
One of the first ancient primates ever to be identified.
A deer-like camel of Oligocene North America.
Was it ancestral to seals or weasels?
The immediate predecessor of the modern elephant.
Could this have been the ancestor of all modern cats?
Could this have been the first true ape?
Better known as the Giant Short-Faced Kangaroo.
This early ape resembled a small gibbon.
An ancient ancestor of modern dugongs and manatees.
The earliest of the deer-like "protoceratids."
This "first whale" looked more like a seal.
A direct (but ancient) ancestor of modern cats.
A squirrel-like mammal with a prehensile tail.
The earliest known ancestor of modern seals.
Could this have been the direct ancestor of human beings?
This "fire beast" resembled a baby elephant.
This South African zebra went extinct in 1883.
The only early mammal known to have hunted dinosaurs.
Yet another early step in the evolution of whales.
This primate "missing link" was discovered in Saudi Arabia.
A short-necked giraffe of the Miocene epoch.
No, it wasn't any more sarcastic than any other prehistoric mammal.
Another intermediate form between reptiles and mammals.
One of the earliest marsupials yet discovered.
This hooved carnivore lived a few million years after the dinosaurs.
This primate may have been ancestral to modern orangutans.
This prehistoric giraffe looked more like a moose.
A lemur-like primate from North America.
Smilodon (Saber-Toothed Tiger)
What most folks know as the "saber-toothed tiger."
Stag Moose (Cervalces Scotti)
A giant, moose-like deer of North America.
Not quite a cross between a Stegosaurus and a mastodon.
This elephant's footprints have been found in the Arabian peninsula.
Steller's Sea Cow (Hydrodamalis)
A prehistoric ancestor of modern dugongs and manatees.
A two-horned rhino of Pleistocene Eurasia.
An ancient ancestor of the modern platypus.
A giant kangaroo of Pleistocene Australia.
Straight-Tusked Elephant (Elephas Antiquus)
This elephant species went extinct 50,000 years ago.
The largest marsupial predator of modern times.
A deer-like mammal with a V-shaped horn on its snout.
This mammal came equipped with its own salad fork.
The biggest of the "multituberculate" mammals.
The immediate predecessor of the modern horse.
An early ancestor of the modern platypus.
A hippo-like rhinoceros of the Miocene epoch.
A widespread elephant of the Miocene epoch.
A marine sloth of Pliocene South America.
Thylacoleo (Marsupial Lion)
The largest carnivorous mammal ever to live in Australia.
A marsupial variant of the saber-toothed cat.
A giant camel of the Pliocene epoch.
A bone-crushing dog of the Miocene epoch.
A strange, rhino-like beast from South America.
A common mammal of the late Jurassic.
A hornless rhinoceros of the Oligocene epoch.
This rhino-like mammal sported three pairs of horns.
A smaller cousin of the Marsupial Lion.
Woolly Mammoth (Mammuthus)
This shaggy beast was hunted by early humans.
Woolly Rhino (Coelodonta)
A shaggy rhinoceros of the Pleistocene epoch.
This unclassifiable saber-tooth was discovered in Florida.
This tiny mammal may be the ancestor of modern rodents.
This early whale may have crawled onto land to give birth.
The earliest known ancestor of the Giant Panda.