| ass |
a mammal with long legs and hooves that is closely related to the horse. A donkey is a domestic ass. Asses look like horses but are smaller and have longer ears. Wild asses live in Africa and Asia and are in danger of becoming extinct. [1/2 definitions] |
| bison |
a very large mammal with a large head, humped shoulders, and short curved horns. Bison used to roam the plains of North America in large herds, but they were hunted until they were almost extinct. North American bison are also called buffalo, but they are not related to the true buffalo of Africa and Asia. Bison have hooves and are closely related to cattle. Bison eat only plants and chew their cud. [1/2 definitions] |
| dinosaur |
one of a group of extinct animals. Some kinds of dinosaurs were the largest animals that ever lived on land. Other dinosaurs were as small as chickens. The first kinds of dinosaurs developed over two hundred million years ago. The last kinds became extinct about sixty-five million years ago. |
| dodo |
a large bird, now extinct, with wings so small that it could not fly. Dodos were once found on islands in the Indian Ocean. |
| endangered |
in danger of becoming extinct. When a type of animal is endangered, it means that few of these animals exist now, and it is possible that there will be no more of these animals in the future. [1/2 definitions] |
| endangered species |
a species of plant or animal that is in danger of becoming extinct. |
| extinction |
the act or process of becoming or making extinct. |
| mammoth |
a very large extinct mammal closely related to elephants. Mammoths were much bigger than elephants, and had shaggy black fur and long tusks that curved upward. Several kinds of mammoths lived in the Northern Hemisphere until the end of the last Ice Age. [1/2 definitions] |
| mastodon |
a very large extinct mammal. Several kinds of mastodons lived in Africa, Europe, Asia, and North America tens of thousands of years ago. The last kind of mastodon became extinct at the end of the last Ice Age. Mammoths and modern elephants may have developed from earlier mastodons. |
| plesiosaur |
an extinct marine reptile with limbs like paddles, a large flattened body, and a short tail. The plesiosaur lived millions of years ago. |
| pterodactyl |
a flying reptile that lived at the same time as dinosaurs. Pterodactyls had wings covered with skin. Some were huge and glided over the oceans and caught fish. They became extinct over sixty-five million years ago. |
| rhinoceros |
a large mammal with hooves and very thick skin. Rhinoceroses have one or two horns on their noses. They eat plants. Wild rhinoceroses live in Africa and southern Asia. Four of the five kinds of rhinoceroses are in danger of becoming extinct. |
| saber-toothed tiger |
a large wild cat with very long teeth curving from its upper jaw. Saber-toothed tigers were carnivores that hunted the young of mammoths and other large animals. The last kinds of saber-toothed tigers became extinct over ten thousand years ago. Modern tigers are not related to saber-toothed tigers. |
| wolf |
a wild mammal that has a pointed nose, pointed ears, and a bushy tail. Wolves are closely related to coyotes, dogs, and foxes. They usually eat birds and other small animals, but they also hunt in packs for larger animals such as deer. Wolves used to be common in Europe, Asia, and North America, but are now extinct or endangered in most areas. [1/2 definitions] |
| zebra |
a large mammal with a striped coat, long legs, and hooves. Zebras are closely related to horses but have shorter manes. They live in large herds in Africa. Several kinds of zebras are in danger of becoming extinct. |