Early Mammals of the Northeast Although today it is hard to imagine seeing mastodons in Connecticut, they were one of the most common species of large mammals, or megafauna, that lived here over a period of several thousand years. By about 9,000 years ago, these and more than 30 other species of mammals and birds disappeared from North America.  Was their extinction the result of changes in the climate or the work of human hunters? The answer is unknown, but today many scientists agree that a combination of environmental and human factors is the most likely explanation. Mastodon (Mammut americanum) Standing up to 10 feet tall at the shoulder, with long tusks and a hairy coat, the American mastodon is an extinct relative of today’s elephant. The mastodon could be found from Alaska to Florida and into South America until its disappearance about 10,000 years ago.  Mastodons were widespread in New England at the same time as large-game hunters, but no undisputed mastodon kill sites have been found in this region. Did the people here hunt these mighty creatures? The answer is unknown. Did You Know...? In the Northeast, much of our knowledge about the mastodon’s presence has come unexpectedly from the trawling nets of fishermen. Mastodon and mammoth teeth have been dredged up in numerous locations off the Atlantic Coast, providing evidence that these animals were indeed here at a time when sea levels were lower and the coast extended out farther. Giant Beaver (Castoroides ohioensis) As their name implies, giant beavers were quite large—six to seven times the size of modern beavers—and weighed about 300 pounds.  Giant beavers were the largest rodents in North America during the Ice Age. While probably clumsy on land, the animals had short legs and webbed feet, suggesting that they were skilled and powerful swimmers. They lived in large, shallow lakes and ponds bordered by marshes and swamps. Fossil remains of giant beavers have been identified at hundreds of North American sites extending from Alaska to Florida. They were probably most common in the region south of the Great Lakes. With the final retreat of the glacial front, the giant beaver’s habitat disappeared and the animals became extinct approximately 9,000 years ago. Dire Wolf (Canis dirus) Larger and more powerfully built than the modern gray wolf, the dire wolf was one of the most common carnivores, or flesh-eaters, during the last Ice Age.  Although the geographic origin of dire wolves is unknown, fossils show they covered an extraordinary range of North and South America—from southern Canada to Peru—until they became extinct between 9,000 and 10,000 years ago.  Dire wolves preyed on large plant-eating animals, including mastodons, horses, and camels. Certain adaptations, such as large teeth and powerful jaws, indicate that these wolves were hunter-scavengers and often fed on carrion, or the remains of dead animals. Packs of dire wolves probably lurked near kill sites in order to take advantage of carcasses abandoned by human hunters. Gray wolves and dire wolves coexisted for thousands of years. However, the extinction of the dire wolf coincided with an increase in the population of gray wolf (Canis lupus) and may have been due to competition. The gray wolf was better adapted to pursuing the smaller, swifter game that populated North America after the demise of the Ice Age megafauna and probably out-hunted its rival.