The American Mastodon (Mammut americanum)

A painting shows a group of several tusked mastodons, similar to modern elephants, bathing in a body of water. Behind them are forest and volcanic mountains.
During the Pliocene, this region's forests and waterways would have provided lush habitat for herds of mastodon.

Mural by Jay Matternes. Image courtesy of the Smithsonian Institution.

A large fossil tooth, discolored, with shallow roots and high, pointed crowns.
Mastodon tooth in the Hagerman Fossil Beds collection.

NPS Photo/Faith Brown

Quick Facts!

  • Common name: American mastodon
  • Scientific name: Mammut americanum
  • Found at Hagerman: tusks and teeth
  • Present: mid-Pliocene to end-Pleistocene (10,500 years ago)
  • Range: fossils have been found across North and Central America, from Alaska to Mexico
  • Description: about 3 m (9.8 ft) tall at the shoulder, upward-curving tusks

Distant Cousins

The mastodon is a member of the order Proboscidea, which also includes the mammoths, modern elephants, and a wide variety of extinct elephant-like species that evolved over the last 60 million years. Mastodons are only distant cousins of mammoths and elephants, with their last shared ancestor living over 20 million years ago!

A section of fossil mastodon tusk, broken off so that the interior is visible. The tusk has growth rings similar to a tree.
A section of mastodon tusk found at Hagerman Fossil Beds. The tusk shows growth rings, similar to a tree!

NPS Photo/Faith Brown

Forest Dwellers

The American mastodon was adapted to living in cool woodlands, which were abundant in Pliocene Hagerman. Specialized teeth with high, pointed crowns worked well for chewing on leaves and twigs.

Mastodon social life may have been similar to modern elephants, with adult females and young living in herds, and mature males remaining mostly solitary. Both males and females had tusks, though males’ were larger and used for competition during the breeding season.

Why aren’t there mammoths at Hagerman?

The fossils found here all date to the mid to late Pliocene, or about 4 to 3 million years ago. Although the mastodon has been around since then, mammoths didn’t arrive in North America until much later, during the Pleistocene ice ages. Mastodons did co-exist in many places with mammoths, but all of North America’s proboscideans went extinct by around 10,500 years ago.

Hagerman Fossil Beds National Monument

Last updated: October 6, 2021