Ambulocetus was an early whale from Eocene Pakistan. It was not a dinosaur and not a modern whale, but a semiaquatic mammal that could move on land and swim in water. Its name means walking whale, and its nearly complete skeleton helped scientists understand how whale ancestors shifted from land toward the sea.

Amebelodon was a shovel-tusked proboscidean that lived mainly in North America during the Miocene. It was an elephant relative with an elongated lower jaw carrying two flattened incisor tusks. The tusks were narrower than Platybelodon’s broad cutting plate, and wear marks show that Amebelodon used them in several ways, especially stripping and scraping bark rather than constantly digging through swamp mud.

The American lion was one of the largest cats of Ice Age North America. It was not a dinosaur, and it was not exactly the same as a modern African lion. Scientists call it Panthera atrox and study its bones, teeth, and La Brea Tar Pits fossils to understand how it hunted and lived.

Amphicyon was a large amphicyonid carnivoran commonly called a bear-dog. It was not a hybrid of a bear and a dog, and it did not belong to either living family. Different species combined powerful jaws, broad feet, flexible bodies, and limbs with both ambush and pursuit features, creating formidable predators and scavengers across the Miocene world.

Anancus was a large elephant-like proboscidean that lived across Africa, Europe, and Asia from the Late Miocene into the Early Pleistocene. It had a short lower jaw, a hanging trunk, ridged molars, and no lower tusks. Its most spectacular features were two slender upper tusks that projected forward in nearly straight lines and could grow longer than a small car.

Andrewsarchus was a mysterious extinct mammal from Eocene Inner Mongolia. It was not a dinosaur, wolf, or bear. Scientists mostly know it from one enormous skull found by an American Museum of Natural History expedition in 1923, so its full body shape, size, and lifestyle are still debated.

Arctotherium was a genus of short-faced bears that lived in South America during the Pleistocene. These bears descended from North American ancestors that crossed the newly formed land connection between the continents. The earliest species, Arctotherium angustidens, included an enormous individual weighing well over a tonne, but evidence from teeth, skulls, and isotopes shows that even this giant probably ate a flexible mixture of meat and plants.

Arsinoitherium was a large extinct mammal from Africa and Arabia. It was not a dinosaur and not a rhinoceros, even though it looked a bit like a rhino wearing two enormous horns. Arsinoitherium belonged near the elephant, hyrax, and sea cow side of the mammal family tree and ate plants in warm swampy habitats.

Astrapotherium was a large plant-eating mammal that lived in South America during the Early and Middle Miocene. It was not an elephant, tapir, hippopotamus, or rhinoceros, but a member of the entirely extinct order Astrapotheria. Four enlarged canine teeth formed tusks, while retracted nasal bones suggest a flexible upper lip or short trunk.

The Atlas Bear was a recently extinct bear from North Africa. It was not a dinosaur and not a lion, but an extinct brown bear population or subspecies. Atlas Bears lived around the Atlas Mountains and nearby areas, and they are remembered as the only bear known from Africa in recent historical times.

The aurochs was a huge wild cattle species and the wild ancestor of domestic cattle. It was not a dinosaur and not the same as a modern farm cow. Aurochs roamed parts of Europe, Asia, and North Africa for thousands of years before the last known individual died in Poland in 1627.

The Bali Tiger was a tiger population from the Indonesian island of Bali. It was not a dinosaur and not the same as the Sumatran tiger that still survives. Bali Tigers were the smallest of the modern tiger island forms and vanished after hunting, shrinking forests, and heavy human pressure.

The Bluebuck, also called the blue antelope, was a recently extinct antelope from South Africa. It was not a dinosaur and not actually bright blue. Its coat looked bluish-gray in some light, and it was related to roan antelopes and sable antelopes.

Borophagus was a stocky bone-crushing dog that lived in North America during the later Miocene and Pliocene. It was a true canid, but it belonged to the extinct borophagine branch rather than the wolf, fox, or domestic-dog branch. A deep skull, strong jaw muscles, and enlarged crushing teeth allowed it to eat flesh, crack bones, and reach nutritious marrow.

Brontotherium is a famous old name connected with huge extinct mammals now often placed with Megacerops and other brontotheres. It was not a dinosaur and not a rhinoceros. These thunder beasts were odd-toed hoofed mammals from Eocene North America, with massive bodies, paired nose horns, and a plant-eating lifestyle.

The Bubal Hartebeest was a recently extinct antelope from North Africa. It was not a dinosaur and not a cow, though it belonged to the same large hoofed mammal family as cattle and antelopes. This sandy-colored hartebeest lived in dry grasslands and desert-edge habitats, and the last known individual was shot in Algeria in 1925.

The Caribbean Monk Seal was a recently extinct seal that lived in the Caribbean Sea and Gulf of Mexico. It was not a dinosaur or sea lion, but a true seal adapted to warm tropical waters. The last confirmed sighting was in 1952, and the species was declared extinct in 2008.

The Caspian Tiger was a tiger population that once lived across parts of Central Asia, the Caucasus, northern Iran, eastern Turkey, and nearby regions. It was not a dinosaur and not a sea animal, despite the Caspian name. This tiger used river forests, reed beds, and tugai habitats before disappearing in the 1900s.

Castoroides was a giant extinct beaver from Ice Age North America. It was not a dinosaur, and it was much larger than modern beavers. Castoroides lived near lakes, wetlands, and waterways, but scientists are cautious about saying it built dams like modern beavers because the evidence is not clear.

The cave bear was a large Ice Age bear that lived in Europe and western Asia. It was not a dinosaur, and it was not the same as a modern brown bear. Cave bears are famous because many of their bones were found in caves, where they likely hibernated during cold seasons.

The cave lion was a large extinct cat from the Ice Age. It was not a dinosaur and was not the same as a modern lion, though it was closely related. Cave lions lived across cold northern landscapes, hunted large prey, appeared in ancient art, and even left frozen cub fossils in Siberia.

Chalicotherium was a strange extinct hoofed mammal from the Miocene. It was not a dinosaur, horse, gorilla, or sloth, even though it looked like a fossil mash-up of several animals. This odd-toed plant eater had long clawed front limbs, shorter back legs, and probably used its claws to pull leafy branches closer.

The Christmas Island Pipistrelle was a tiny bat found only on Christmas Island, an Australian territory in the Indian Ocean. It was not a bird or flying mouse, but a small insect-eating bat. The last known bat was detected by its call in August 2009, and the species was later declared extinct.

Daeodon was a giant extinct entelodont from North America. It was not a dinosaur and not a true pig, even though entelodonts are often nicknamed hell pigs. Daeodon had a huge skull, long legs, two-toed hooves, powerful jaws, and probably ate a mixed diet that included carrion, roots, plants, and animal foods.

Deinotherium was a giant proboscidean that lived across Africa, Europe, and Asia for millions of years. It resembled an elephant in its column-like legs and trunk, but it had no long upper tusks. Instead, a pair of enlarged lower incisors curved downward and backward from the front of the jaw, creating one of the strangest heads in mammal history.

Desmostylus was a large aquatic mammal that lived around the North Pacific during the Late Oligocene and Miocene. It belonged to Desmostylia, an extinct order with no living members. A long skull, forward-pointing tusk-like teeth, stout limbs, and molars built from fused vertical columns gave it a body and mouth unlike those of any modern mammal.

Diprotodon was the largest known marsupial and one of the giants of Pleistocene Australia. It was a plant-eating vombatiform related more closely to wombats and koalas than to rhinoceroses or hippopotamuses. A barrel-shaped body, pillar-like limbs, enormous lower incisors, ridged molars, and a surprisingly hollow but strong skull helped this multi-tonne herbivore travel widely and process tough vegetation.

The dire wolf was an extinct Ice Age predator from the Americas. It looked wolf-like, but new research shows it was not just a bigger gray wolf. Dire wolves had strong jaws, powerful teeth, and many fossils at La Brea Tar Pits, where they are one of the most famous Ice Age mammals.

Doedicurus was a giant armored mammal from South America. It was not a dinosaur, and it was not an ankylosaur, even though its heavy tail club can look a little dinosaur-like. Doedicurus was a glyptodont, an extinct armadillo relative with a huge shell and a powerful clubbed tail.

Elasmotherium was a giant extinct rhinoceros relative from Ice Age Eurasia. It was not a dinosaur and not a horse, even though its nickname, the Siberian unicorn, sounds magical. Scientists think it lived on open grasslands and may have survived until less than 40,000 years ago.

Embolotherium was a gigantic brontothere that lived in Mongolia during the Late Eocene. It was an odd-toed hoofed mammal related to the broader group containing rhinos, horses, and tapirs, but it was not a true rhinoceros. Its most remarkable feature was a long battering-ram-shaped structure formed from the nasal and frontal bones. The structure was hollow and connected with an enlarged nasal cavity, so scientists think it may have helped produce or amplify sounds rather than serving as a weapon.

Enhydriodon was a genus of giant prehistoric otters that lived in Africa and Asia. The largest known species, Enhydriodon omoensis, inhabited the Lower Omo Valley of Ethiopia between about 3.4 and 2.5 million years ago. It may have weighed around 200 kilograms or more and probably spent much more time on land than living otters, using broad rounded teeth to crush a varied diet of aquatic and terrestrial prey.

Entelodon was a large extinct hoofed mammal from the Paleogene. It was not a dinosaur and not a true pig, even though entelodonts are often nicknamed hell pigs. Entelodon had a huge head, powerful teeth, long legs, and probably ate a mix of meat, plants, carrion, roots, and other tough foods.

Eohippus is the popular name for Hyracotherium, a tiny early horse relative from the Eocene. It was not a dinosaur and not a modern horse. This small forest browser had a short face, low-crowned teeth, four toes on each front foot, three toes on each back foot, and helped scientists understand the early story of horse evolution.

Epicyon was a giant bone-crushing dog that lived in North America during the Late Miocene and Early Pliocene. It was a true member of the dog family but was not a wolf, hyena, or direct ancestor of modern dogs. A broad skull, enlarged jaw muscles, strong premolars, and a massive body allowed the largest species to process flesh, hide, and bone.

The Falkland Islands Wolf, also called the warrah, was a recently extinct canid that lived only on the Falkland Islands in the South Atlantic. It was not a true wolf and not a fox, though it looked dog-like. It was the only native land mammal of the Falkland Islands and became extinct in 1876.

Giant ground sloths were extinct mammals related to modern sloths. They were not dinosaurs, and they did not live in trees like today’s small sloths. Different kinds lived in North and South America, from forest browsers such as Megalonyx to enormous South American forms such as Megatherium.

Gigantopithecus was a giant extinct ape from Pleistocene southern China. It was not a dinosaur, gorilla, or Bigfoot, though it may have been the largest primate ever known. Scientists mostly know it from jaws and thousands of teeth, so its full body is reconstructed carefully from clues rather than a complete skeleton.

Glossotherium was a giant ground sloth that lived across South America during the Pliocene and Pleistocene. Unlike modern tree sloths, it walked on the ground and grew to the size of a small car. Its broad muzzle gathered large mouthfuls of grasses and herbs, while massive forelimbs and curved claws made it a powerful digger capable of excavating enormous burrows.

Glyptodon was a giant armored mammal from South America. It was not a dinosaur, and it was not a turtle, even though its huge bony shell can make people think of one. Glyptodon was a glyptodont, a large extinct armadillo relative with a domed carapace made from many bony plates.

Hesperocyon was one of the earliest well-known members of the dog family. It lived in North America from the Late Eocene into the Oligocene, long before wolves, foxes, or domestic dogs appeared. Although its teeth and ear region reveal a true canid, its long flexible body, low limbs, plantigrade feet, and possible climbing ability made it look more like a civet or small mongoose than a modern dog.

Homotherium was an extinct scimitar-toothed cat that lived in parts of Africa, Eurasia, and the Americas. It was not a dinosaur and not the same as Smilodon. Homotherium had shorter, flatter saber teeth, long legs, and a body that may have been better for moving through open habitats.

Hyaenodon was an extinct meat-eating mammal from the group Hyaenodonta. It was not a dinosaur and not a true hyena, even though its name means hyena tooth. Different Hyaenodon species lived across North America and Eurasia for millions of years, using sharp slicing teeth to eat meat.

Hyracodon was a lightly built rhinocerotoid that lived in North America from the Late Eocene into the Oligocene. It was not a horse or a modern rhinoceros. Unlike today’s heavy rhinos, it had no horn, carried a relatively small skull on a longer neck, and walked on long slender legs. Its horse-like proportions earned members of its family the nickname running rhinos, although fossils cannot tell us exactly how fast Hyracodon could run.

The Irish elk was a giant extinct deer from the Ice Age. It was not a dinosaur, and despite its name, it was not a true elk like the North American elk. Male Irish elk are famous for enormous antlers that could spread wider than a small car.

The Japanese Sea Lion was a recently extinct marine mammal from the western North Pacific. It was not a dinosaur or true seal, but an eared seal related to California sea lions. It lived around Japan, Korea, and nearby coasts, formed breeding colonies, and disappeared after heavy hunting and other human pressures.

The Javan Tiger was a tiger population from the Indonesian island of Java. It was not a dinosaur, and it was not the same as the Sumatran tiger still living today. It was officially treated as extinct after no confirmed evidence was found, though a disputed 2019 hair sample has kept the mystery door slightly open.

Josephoartigasia was a gigantic plant-eating rodent that lived in what is now Uruguay during the Pliocene. The best-known species, Josephoartigasia monesi, is represented by an enormous skull about 53 centimetres long. It may have weighed around 480 to 500 kilograms according to a recent estimate, although older studies proposed much larger masses. Its huge continuously growing incisors could deliver a powerful bite and may also have worked like tusks for digging, cutting plants, or defense.

The Lesser Bilby was a small extinct marsupial from Australia’s deserts. It was related to the living Greater Bilby, but smaller, paler, and with a mostly white tail. Scientists know it from only a small number of specimens, Indigenous knowledge, and scattered records from arid Australia.

Litopterna was an extinct order of native South American hoofed mammals. They were not dinosaurs, horses, camels, or llamas, although some looked a bit like familiar hoofed animals. Litopterns evolved in South America after the dinosaurs, spread into many shapes, and included long-necked Macrauchenia, one of the last members of the group.

Machairodus was a large saber-toothed cat that lived during the Late Miocene. It was a true member of the cat family but was not a tiger or the same animal as Smilodon. The well-known species Machairodus aphanistus combined long, flattened upper canines with a skull that was less extremely modified than those of later saber-toothed cats, while strong neck muscles helped control its dangerous bite.

Macrauchenia was a strange extinct South American mammal from the Ice Age. It was not a dinosaur, camel, llama, or horse, even though its long neck and body can look camel-like. Macrauchenia belonged to Litopterna, a vanished group of native South American hoofed mammals, and its nostrils sat high on the skull in a way that still makes scientists debate its face.

Mastodons were extinct elephant relatives that lived in North America during the Ice Age. They were not dinosaurs, and they were not the same as mammoths. Mastodons had tusks, trunks, heavy bodies, and bumpy cone-shaped molars suited for browsing leaves, twigs, and forest plants.

Megaloceros was a genus of giant deer from the Ice Age. Its most famous species, Megaloceros giganteus, is often called the Irish elk or giant deer, but it was not a true modern elk. Male Megaloceros are famous for enormous antlers that spread wider than almost any deer antlers known.

Megantereon was a stocky saber-toothed cat that lived across Africa, Europe, and Asia during the Pliocene and Pleistocene. It was not a tiger, although it belonged to the cat family. Flattened upper canines, a protective flange on the lower jaw, powerful front limbs, and a strong neck suggest that it ambushed prey, wrestled it down, and delivered a carefully placed killing bite.

Megatherium was a giant ground sloth from South America. It was not a dinosaur, and it was not a tree sloth like the small sloths alive today. Megatherium was an enormous Ice Age mammal with huge claws, a strong tail, and a body built for walking on the ground and reaching plants.

Megistotherium was a huge extinct meat-eating mammal from the Miocene of Africa. It was not a dinosaur and not a true hyena. Megistotherium osteothlastes was a hyaenodont, a vanished kind of carnivorous mammal, and it is famous for a large skull from Gebel Zelten in Libya.

Merychippus was an extinct horse relative from Miocene North America. It was not a dinosaur and not exactly the same as a modern horse, but it was an important step in horse evolution. Merychippus kept three toes, had longer legs than earlier horses, and developed high-crowned teeth that helped it graze on tougher grasses.

Mesohippus was an extinct early horse from Oligocene North America. It was not a dinosaur and not a modern horse. Its name means middle horse because it lived after tiny early horses and before later, more grassland-adapted horses. Mesohippus had three toes on each foot, longer legs than earlier horses, and teeth suited for browsing leaves.

Moeritherium was an early proboscidean that lived in northern Africa during the Eocene Epoch. It was not a modern elephant and probably lacked a long elephant-style trunk. A long body, short limbs, high-set eyes and ears, and chemical clues from its teeth suggest that it spent substantial time in or near water while feeding on soft vegetation.

Moropus was a strange extinct hoofed mammal from Miocene North America. It was not a dinosaur, horse, gorilla, or sloth, but it belonged to the odd-toed hoofed mammal branch that also includes horses, rhinos, and tapirs. Moropus had longer front limbs, a somewhat long neck, and claws instead of normal hooves, probably useful for pulling down leafy branches.

Neochoerus was an extinct genus of giant capybaras that lived across parts of North, Central, and South America during the Pliocene and Pleistocene. It was a true rodent closely related to living capybaras, not a pig or hippopotamus. Its barrel-shaped body, short legs, high-crowned teeth, and frequent association with lakes and rivers suggest a plant-eating, water-loving lifestyle.

Neoepiblema was a giant South American rodent that lived during the Late Miocene. It belonged to an extinct chinchilloid family called Neoepiblemidae and was not a giant rat. Fossils from western Amazonia show a heavy-bodied herbivore with powerful limbs, a long skull, ever-growing teeth, and the ability to walk on land while possibly digging or swimming near rivers and wetlands.

Notoungulates were an extinct order of native South American hoofed mammals. They were not dinosaurs and not the same as modern horses, cows, rhinos, or deer. The group was amazingly diverse, with tiny rabbit-like forms, sheep-like grazers, and huge rhino-like plant eaters such as Toxodon.

Nuralagus was a giant extinct rabbit relative from Menorca in the Mediterranean Sea. It was not a dinosaur and not a monster bunny, but it was the largest known lagomorph. Living on an island with few large predators, Nuralagus grew bulky, had shorter ears and eyes than many rabbits, and probably moved slowly instead of leaping like modern rabbits.

Pakicetus was one of the earliest known whale relatives from Eocene Pakistan. It was not a dinosaur and not a modern whale. Pakicetus had long legs, a land-mammal body, and special ear bones that link it to whales, making it one of the most famous fossils in the story of how whales evolved from land-dwelling ancestors.

Palaeoloxodon was an extinct genus of elephants that included the famous straight-tusked elephants. It was not a dinosaur and not a woolly mammoth, though it lived during the Ice Age alongside many other giant mammals. Some Palaeoloxodon species were enormous forest elephants, while island species became tiny dwarf elephants.

Palaeomastodon was an early elephantiform proboscidean that lived in North Africa during the Oligocene Epoch. It was not a modern elephant or true mastodon, but it showed several features that later became familiar in elephant relatives. Its skull probably supported a short muscular trunk, while an elongated lower jaw carried broad forward-pointing tusks beneath a pair of upper tusks.

Palorchestes was an unusual extinct Australian marsupial often nicknamed the marsupial tapir. It was not a real tapir and not a dinosaur. Its skull suggests it may have had a short trunk-like snout, and its powerful forelimbs and large claws may have helped it pull down branches or dig for roots.

Panochthus was a giant armored glyptodont that lived across much of South America during the Pleistocene. It was a mammal and a relative of armadillos, not a dinosaur or turtle. Hundreds of interlocking osteoderms formed a domed carapace over its body, while the end of its tail was enclosed in a rigid bony tube that could function as a formidable defensive or fighting weapon.

Paraceratherium was a gigantic extinct hornless rhinoceros relative from the Oligocene. It was not a dinosaur and not an elephant, even though it was one of the biggest land mammals ever. This long-necked browser lived across parts of Asia and eastern Europe, reaching high branches with a huge body, long legs, and possibly a flexible upper lip.

Parapropalaehoplophorus was a small early glyptodont that lived in northern Chile during the Early Miocene. Glyptodonts were heavily armored relatives of armadillos, but this species was far smaller than later giants such as Glyptodon and Panochthus. Its body was protected by a solid mosaic of rounded osteoderms, and its teeth changed from simple shapes at the front of the jaw to three-lobed grinding teeth farther back.

Pelorovis was a genus of large wild cattle that lived in Africa during the Early Pleistocene. The best-known species, Pelorovis oldowayensis, had a long face and massive horn cores curving outward and upward in broad half-moons. It was a grazing bovid related to cattle and buffalo, but its exact family position is debated, and some scientists place the genus close to or inside Bos.

Platybelodon was a strange shovel-tusked proboscidean that lived in Asia during the Middle Miocene. It was an elephant relative, but not a true elephant or modern elephant ancestor. Its lower jaw widened into a broad scoop carrying flat incisor tusks. Older artwork showed it dredging swamp mud, but wear marks and biomechanical studies instead suggest that its trunk and lower tusks cut, stripped, or processed tough vegetation.

Pliohippus was an extinct horse relative from late Miocene North America. It was not a dinosaur and not exactly the direct ancestor of modern horses, even though older books often showed it that way. Pliohippus looked very horse-like, had long slim legs, usually a strong main toe, grazing teeth, and deep facial pits on its skull.

Proconsul was an extinct early ape from the Miocene of eastern Africa. It was not a dinosaur, monkey, chimpanzee, or human, but it helps scientists study the early ape branch of primate evolution. Proconsul had no tail like apes, but many body features still looked monkey-like, making it a famous fossil blend of old and new traits.

Procoptodon was a giant extinct short-faced kangaroo from Pleistocene Australia. It was not a dinosaur and not a normal modern kangaroo. The best-known species, Procoptodon goliah, was the largest kangaroo known to science, with a short flat face, powerful legs, long clawed fingers, and unusual single-toed feet.

The Pyrenean Ibex, also called the bucardo, was a recently extinct wild goat from the Pyrenees and nearby mountains. It was not a dinosaur and not a domestic goat. The last natural Pyrenean Ibex, a female named Celia, died in January 2000, and a cloned baby was born in 2003 but lived only a few minutes.

Pyrotherium was a giant plant-eating South American mammal from the Late Oligocene. It looked somewhat elephant-like, but it was not an elephant or proboscidean. A massive skull, two pairs of upper tusks, one pair of lower tusks, ridged cheek teeth, and extremely robust weight-bearing bones made this fire beast one of the strangest large mammals in South American history.

The quagga was a recently extinct zebra from southern Africa. It was not a dinosaur and not a horse exactly, but a subspecies of plains zebra. Quaggas were famous for having stripes mostly on the front of the body, while the back looked browner and less striped.

Samotherium was an extinct giraffid that lived across parts of Europe and Asia during the Late Miocene, with related records extending into nearby regions. It was a true member of the giraffe family but was not simply a short modern giraffe. Samotherium major had a neck anatomically intermediate between the short-necked okapi and the extremely long-necked giraffe, while long legs and a pair of ossicones completed its distinctive appearance.

Schomburgk's Deer was a recently extinct deer from central Thailand. It was not a dinosaur or a regular farm deer. This graceful wetland deer lived in swampy plains and long grass near the Chao Phraya River system, and males were famous for amazing basket-like antlers with many points.

The Sea Mink was a recently extinct mammal from the rocky coasts of northeastern North America. It was not a sea otter or seal, but a large mink relative. It lived around the Gulf of Maine region, ate coastal prey, and was hunted heavily for its fur before scientists had much chance to study it alive.

The short-faced bear was a giant Ice Age bear from North America. It was not a dinosaur, and it was not just a bigger version of a modern grizzly. Scientists study its bones, teeth, caves, and chemistry clues to understand whether it hunted, scavenged, ate plants, or did a mix of all three.

Sinomastodon was an elephant-like proboscidean that lived across parts of Asia from the Late Miocene into the Early Pleistocene. It was not a mastodon from the genus Mammut, despite its name meaning Chinese mastodon. Its short lower jaw lacked permanent projecting tusks, while two upper tusks curved gently upward and bunodont molars crushed plant food.

Sinomegaceros was a genus of giant deer that lived across central and eastern Asia from the Late Pliocene into the Late Pleistocene. It was related to other giant deer such as Megaloceros, but its antlers had a distinctive broad, flattened brow tine near the base. Species varied greatly in size and antler shape, and ancient DNA suggests that eastern Sinomegaceros and western Megaloceros had a tangled evolutionary history that may have included interbreeding.

Sivatherium was a huge extinct giraffe relative from the late Neogene. It was not a dinosaur and not a moose, even though its heavy body and headgear can look moose-like in drawings. This giant giraffid had large ossicones on its head, a shorter neck than modern giraffes, and lived across parts of Africa and Asia.

Smilodon was a powerful saber-toothed cat from the Ice Age. It was not a dinosaur and not a true tiger, even though people often call it the saber-toothed tiger. Smilodon had huge upper canine teeth, strong front legs, and fossils famous from places such as La Brea Tar Pits.

Stegodon was an extinct elephant relative that lived across Africa and Asia for millions of years. It was not a dinosaur and not exactly a modern elephant, though it was part of the proboscidean family tree. Stegodon is famous for its ridged molars, long tusks, giant mainland species, and dwarf island species such as Stegodon florensis on Flores.

Steller's Sea Cow was a giant marine mammal that lived around the Commander Islands in the cold Bering Sea. It was not a dinosaur, seal, or whale, but a sirenian related to dugongs and manatees. Europeans first described it in 1741, and it was hunted to extinction by 1768.

The steppe bison was an extinct Ice Age bison that lived across Eurasia and North America. It was not a dinosaur, but a hoofed mammal related to modern bison. Steppe bison had large horns, a heavy body, and lived in open mammoth-steppe habitats with mammoths, horses, wolves, and big cats.

Synthetoceras was an extinct hoofed mammal from the Late Miocene of North America. It was not a dinosaur, deer, antelope, or giraffe, though it had strange horn-like structures. This protoceratid had two horns above the eyes and, in males, a long Y-shaped horn on the snout, making it one of the oddest-looking herbivores of its time.

The Syrian Wild Ass was a recently extinct wild equid from West Asia. It was not a donkey breed or a small horse, but an extinct subspecies of onager. This fast desert animal was one of the smallest wild horse relatives and lived in dry grasslands, deserts, and steppes before disappearing in the 1920s.

The Tasmanian tiger, also called the thylacine, was a recently extinct carnivorous marsupial. It was not a tiger and not a wolf, even though its striped back and dog-like body gave it both nicknames. It once lived in mainland Australia and New Guinea, but survived into modern times on Tasmania.

Thylacoleo was an extinct Australian marsupial often called the marsupial lion. It was not a real lion and not a dinosaur. The best-known species, Thylacoleo carnifex, was Australia's largest known mammalian carnivore and may have ambushed big Pleistocene animals with powerful forelimbs, sharp claws, and slicing teeth.

The Toolache Wallaby was a recently extinct marsupial from southeastern Australia. It was not a kangaroo, though it was a close kangaroo-family relative. This elegant wallaby lived in grassy and scrubby habitats of South Australia and nearby regions, but hunting, habitat loss, and introduced predators pushed it to extinction in the 1900s.

Toxodon was a huge extinct South American mammal from the Ice Age. It was not a dinosaur, rhinoceros, or hippopotamus, even though its heavy body can look rhino-like in drawings. Toxodon belonged to Notoungulata, a vanished group of native South American hoofed mammals, and it became famous after Charles Darwin collected its fossils.

Uintatherium was a giant extinct mammal from the Eocene. It was not a dinosaur, rhinoceros, or elephant. This strange plant eater had a heavy body, three pairs of bony skull knobs, saber-like upper canine teeth, and lived in warm forests long before humans existed.

The Western Black Rhinoceros was a recently extinct subspecies of black rhinoceros from Africa. It was not a dinosaur, and it was not the same as every black rhino alive today. This browsing rhino once lived in parts of western and central Africa, but poaching pushed it to extinction, and the IUCN declared it extinct in 2011.

The woolly mammoth was an Ice Age elephant relative with long shaggy hair, a thick fat layer, small ears, a trunk, and huge curved tusks. It lived in cold northern habitats across Eurasia and North America. The last woolly mammoths survived on islands until about 4,000 years ago.

The woolly rhinoceros was an extinct Ice Age mammal with thick fur, a large front horn, a smaller nose horn, and a sturdy body built for cold open habitats. It lived across northern Eurasia in steppe-tundra landscapes with mammoths, bison, reindeer, and other Ice Age animals.

Zygomaturus was a giant extinct marsupial from ancient Australia. It was not a dinosaur and not a rhinoceros, though people sometimes compare its bulky body with a hippo or rhino. Zygomaturus trilobus was a large plant-eater related to Diprotodon, wombats, and other diprotodontid marsupials.