By | September 9, 2016

This family of mostly carnivorous mammals includes dogs, bears, foxes, raccoons, weasels, and perhaps surprisingly—seals, sea lions, and walruses, which evolved from bearlike ancestors. Caniform means “dog-shaped,” but early caniforms were tree-climbing animals that resembled pine martens. As they colonized the ground they evolved into more dog- and then bearlike forms.


Key features
■ Long snouts
■ Four shearing teeth at front of jaw (carnassials)
■ Walked on all fours
■ Most were unable to retract (pull back) their claws into a protective sheath, as cats can do.

They first appeared in the Paleogene Period (about 55 million years ago), and still exist today.

Canis dirus (CAY-niss DIE-russ)


When: 2 million–10,000 years ago (Late Pleistocene)

Fossil location: Canada, USA, Mexico

Habitat: Plains

Length: 5 ft (1.5 m)

Diet: Meat

Canis dirus (“dire wolf ”) was a large animal with much stronger jaws and bigger teeth than modern wolves. Its limbs were shorter than those of its cousin the gray wolf, so it probably spent more time scavenging than hunting. The dire wolf died out in the last ice age, possibly because of the extinction of the large herbivores on which it fed. Thousands of fossils have been found in La Brea tar pits in California (search the article), suggesting it was a pack hunter.

Arctodus (ARK-toe-duss)


When: 2 million–10,000 years ago (Late Pleistocene)

Fossil location: Canada, USA, Mexico

Habitat: Mountains and woodlands

Length: 10 ft (3 m)

Diet: Omnivorous

This huge predator was the largest bear ever known. When it reared up on its hindlimbs, it was more than twice the height of a man. Arctodus charged at prey such as deer, bison, and horses, outrunning them on its long legs. It also ate plant foods and probably scavenged on carcasses, too.

Amphicyon (am-fee-SIGH-on)


When: 30–20 million years ago (Neogene)

Fossil location: N. America, Spain, Germany, France

Habitat: Plains

Length: 6. ft (2 m)

Diet: Omnivorous

Also called a bear-dog, Amphicyon looked like a cross between a dog and a bear. But its large build—it was the size of a modern grizzly bear—and diet of plants and meat made it more like a bear than a dog. It had wolflike teeth, powerful limbs, and a long tail. Since it was too heavily built to chase prey over long distances, it probably ambushed victims, charging and killing them with its powerful jaws and teeth.

Enaliarctos (en-AL-ee-ARK-toss)


When: 20 million years ago (Neogene)

Fossil location: USA

Habitat: Coasts

Length: 3 ft (1 m)

Diet: Fish, meat, shellfish

Enaliarctos was one of the earliest members of the pinniped family, which includes seals, sea lions, and walruses. It seems to have divided its time between water and land, rather like a modern sea lion does. With its webbed feet and flippers, Enaliarctos swam easily through water, although it was more clumsy on land. Its large eyes helped it to see in deep water, and it had specialized inner ears for hearing underwater. Its teeth were well suited to slicing through flesh, and it probably returned to the shore to eat the fish or shellfish it caught.

Miacis (me-AH-kiss)


The needle-sharp claws on Miacis’s toes helped it to hold onto trees as it climbed.

When: 55 million years ago (Paleogene)

Fossil location: Europe, N. America

Habitat: Tropical forests

Length: 1 ft (0.3 m)

Diet: Small mammals, reptiles, birds

Miacis was a member of the family from which all modern carnivorous mammals evolved. A small animal about the size of a weasel, it had a similarly slender body and short legs.
Miacis lived high up in trees, using its agile limbs to climb. Its long tail helped it balance as it leaped from branch to branch. It probably hunted smaller animals, such as small mammals and reptiles, using its sharp teeth to tear off flesh in a scissorlike action. It might also have eaten eggs and fruit. Its vision, though good, was not as sharp as that of modern dogs.


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