A full fossil skeleton of the Megatherium, an elephant sized ground sloth. The animal was extinct during the Pleistocene, and found in Buenos Aires. The shape of the skull suggests that the animal is an ancestor of the sloth and anteater.

Full Megatherium Fossil Skeleton

A full fossil skeleton of the Megatherium, an elephant sized ground sloth. The animal was extinct during…

Illustration showing the upper molar teeth of the megatherium, a giant sloth. The teeth were 7 to 8 inches inside the gums.

Upper Molar Teeth of Megatherium Fossil Skeleton

Illustration showing the upper molar teeth of the megatherium, a giant sloth. The teeth were 7 to 8…

The sloth differs from all other arboreal four-legged mammals in its manner of climbing. It always has its back downward. It eats leaves and moves very slowly and deliberately.

Sloth

The sloth differs from all other arboreal four-legged mammals in its manner of climbing. It always has…

The squirrel is a medium sized rodent and can be found in most parts of the world.

Squirrel

The squirrel is a medium sized rodent and can be found in most parts of the world.

the stag is the male deer.

Stag

the stag is the male deer.

Digestive system of a mammal. (g) gullet; (s) stomach; (sm) small intestine; (lm) large intestine; (r) termination of the large intestine.

Digestive system

Digestive system of a mammal. (g) gullet; (s) stomach; (sm) small intestine; (lm) large intestine; (r)…

Tapirs are found in South America. They have four toes in front and three behind. The snout is prolonged.

Tapir

Tapirs are found in South America. They have four toes in front and three behind. The snout is prolonged.

Teeth of the right side of the lower jaw of the Chimpanzee. (i) incisors; (c) canine tooth; (pm) premolars; (m) molars.

Chimpanzee Teeth

Teeth of the right side of the lower jaw of the Chimpanzee. (i) incisors; (c) canine tooth; (pm) premolars;…

The tiger found only in Asia, stands three feet high at the shoulders, but can be as long as eight feet. Its coat has black stripes on a background of reddish yellow.

Tiger

The tiger found only in Asia, stands three feet high at the shoulders, but can be as long as eight feet.…

"Tinoceras, or tinotherium, is a genus of mammals now extinct, found in the Eocene, and representing the order Dinocerata. The individuals were all large, some of them nearly equaling the elephants, while the brain was smaller than that of any living or fossil mammal."—(Charles Leonard-Stuart, 1911)

Tinoceras

"Tinoceras, or tinotherium, is a genus of mammals now extinct, found in the Eocene, and representing…

The vertebra of the whale. (c) body; (n n ) arches enclosing the spinal cord.

Whale vertebra

The vertebra of the whale. (c) body; (n n ) arches enclosing the spinal cord.

This sea mammal is known for the great length of the canine teeth of the upper jaw, sometimes reaching two feet. It uses these tusks for defense and in gathering its food.

Walrus

This sea mammal is known for the great length of the canine teeth of the upper jaw, sometimes reaching…

Weasels are small, carnivorous mammals. They are effective in exterminating rats and mice from farms, along with the occasional egg.

Weasel

Weasels are small, carnivorous mammals. They are effective in exterminating rats and mice from farms,…

The name given to certain whales closely allied to the common or whalebone whales, but distinguished by having a dorsal fin, with the throat and under arts wrinkled with deep longitudinal folds, which are supposed to be susceptible of great dilation, but the use of which is as yet unknown.

Rorqual Whale Side

The name given to certain whales closely allied to the common or whalebone whales, but distinguished…

The wolf belongs to the dog family. There are three recognized species of wolf and they are generally found in wilder areas.

Wolf

The wolf belongs to the dog family. There are three recognized species of wolf and they are generally…

Wolverines can be found in North America. They are fierce short animals that will attack just about anything. They have a bushy tail, and strong claws.

Wolverine

Wolverines can be found in North America. They are fierce short animals that will attack just about…

An illustration of a woman feeding two squirrels.

Woman Feeding Squirrels

An illustration of a woman feeding two squirrels.

A hoofed, herbivorous mammal found in Africa. It is known for its distinct and regular stripes of black or brown on a white background.

Zebra

A hoofed, herbivorous mammal found in Africa. It is known for its distinct and regular stripes of black…

A zebra

Zebra

A zebra