A mastodon was a large, elephant-like mammal that roamed North America for millions of years before going extinct roughly 10,000 years ago. Though often confused with woolly mammoths, mastodons were a distinct animal with a different body shape, different teeth, and a completely different diet. They belonged to the same biological order as modern elephants, but their evolutionary lines split more than 20 million years ago, making them only distant cousins.
Size and Build
Mastodons were comparable in size to today’s elephants. Males stood up to 10 feet (3.1 meters) at the shoulder, while females were smaller at around 7 feet (2.1 meters). A fully grown adult could weigh as much as 6 tons. Their body plan was stockier and more compact than a mammoth’s, with a lower, flatter skull and a longer torso relative to their height.
How Mastodons Differed From Mammoths
The easiest way to tell these two animals apart is their teeth. Mastodon molars had rows of cone-shaped cusps, ideal for crushing woody material like twigs and bark. In fact, the name “mastodon” comes from the Latin and Greek words for “breast tooth,” a reference to those distinctive rounded points. Mammoth teeth, by contrast, had flat, ridged surfaces designed for grinding grass.
Their tusks were also different. Mastodons had shorter, straighter tusks, while mammoths carried the long, dramatically curved tusks most people picture. These differences reflect two animals adapted to very different lifestyles: mastodons were browsers that fed in forests, while mammoths were grazers of open grasslands and tundra.
Diet and Habitat
Mastodons ate bark, twigs, leaves, and other tough plant material from shrubs and small trees. Microscopic wear patterns on fossilized teeth confirm a diet dominated by woody plants, though the exact mix varied by region depending on what vegetation was available. This browsing lifestyle kept them in forested and semi-forested environments across North America, from the eastern woodlands to swampy lowlands.
At their peak range, mastodons even reached the Arctic and Subarctic. But as ice sheets advanced and retreated over hundreds of thousands of years, their range shifted. During the final stretch of their existence, they were confined to areas south of the massive ice sheets that covered much of Canada.
Life Cycle and Behavior
Scientists have reconstructed surprisingly detailed life histories for individual mastodons by studying the growth layers in their tusks, which record yearly patterns much like tree rings. One well-studied male, known as the Buesching mastodon, lived to about 34 years old. His tusk growth patterns show he separated from his natal herd around age 12, which is typical for male mastodons and closely mirrors the age when modern male elephants leave their family groups.
After reaching maturity, male mastodons appear to have changed their movement patterns significantly, ranging over larger areas. This mirrors the behavior of living elephants, where mature bulls travel widely while females and young tend to stay in more familiar territory.
Humans and Mastodons
People in North America encountered mastodons firsthand. At the Manis site in Washington state, researchers found a projectile point made from mastodon bone embedded in a mastodon rib. Radiocarbon dating places this at 13,800 years ago, roughly two thousand years before the Clovis culture, long considered the first big-game hunters in the Americas. This is direct physical evidence of humans hunting (or at least attacking) these animals.
That said, archaeological evidence of human predation on mastodons is remarkably scarce. Across all of North America, only about 16 sites show clear signs of humans killing or scavenging any of the large ice age mammals, and only five types of animals appear at those sites: mammoth, mastodon, gomphothere, horse, and camel. Hundreds of millions of large mammals are estimated to have lived on the continent when human hunters arrived, making the thin evidence of direct killing a persistent puzzle in the extinction debate.
Why Mastodons Went Extinct
Mastodons disappeared around 10,000 years ago as part of a massive wave of extinctions that wiped out roughly 70 species of large mammals in North America. Two main explanations have competed for decades. The “overkill” hypothesis argues that human hunters, particularly the Clovis culture that appeared around 13,400 years ago, spread across the continent and drove these animals to extinction within centuries. The climate hypothesis points to the dramatic environmental upheaval as Earth shifted from a glacial period to the warmer conditions we live in today.
Neither explanation works perfectly on its own. Overkill proponents note that mastodons survived multiple previous ice ages and only disappeared during the one when humans were present. Climate advocates counter that the archaeological record simply doesn’t show enough evidence of hunting to account for killing off hundreds of millions of animals. The reality is likely complex: climate change reshaped habitats and stressed populations, while human hunting may have added pressure that tipped already vulnerable species over the edge. The specific factors that doomed forest-dwelling mastodons in the Midwest were probably quite different from those that eliminated horses and camels on western grasslands.
Mastodons in the Fossil Record
Mastodon fossils are among the most commonly found large ice age mammals in North America, particularly in the Great Lakes region and the eastern United States. Teeth and tusks preserve well and are frequently discovered during construction projects, in gravel pits, and along eroding riverbanks. The abundance of these fossils is part of what has allowed scientists to study their diet, migration, and life history in such detail.
The oldest traces of mastodon DNA come from an extraordinary source: two-million-year-old environmental DNA extracted from sediments in Greenland, where genetic material from mastodons, reindeer, rodents, and geese was preserved in ancient deposits. This pushes the known genetic record of mastodons far beyond what bones alone could provide, confirming their deep evolutionary roots alongside other now-vanished ecosystems.