American Mastodon

Mammut americanum

  • Height: 8-10 ft 
  • Weight: 8,000-12,000 Pounds  
  • Closest Living Relative: Distant cousin of elephants – last common ancestor 27 million years ago.
  • Status: Extinct 10,500 years ago due to changing habitats, from cool wet forests to dry open-land and also human hunting pressure. It is still debated what the main cause of extinction was.


The American mastodon is in the same biological “order” as elephants and mammoths, and has a lot of similarities to these animals. The mastodon was a large, burly mammal that was built to push through dense forests. Large tusks protruded from their skull, similar in shape to modern elephants, and much straighter than Mammoth tusks. Mastodons were shorter and stockier than elephants and mammoths, and had a large coat of thick fur to keep them warm. They had very thick leg bones to help support their large size.
The Columbian Mammoth was an herbivore, primarily a grazer, eating mostly grasses, along with leaves and flowers and some twigs. Their teeth were flat, with small ridges like a file, allowing them to grind up the leaves and grasses.  It is expected that these mammoths had to spend most of their day (16-18 hours) eating to consume enough calories, close to 150,000 calories a day! (That’s the calorie intake an adult human needs in two months!)
Mastodon families consisted of mothers and young. The males would leave the group and go solo or join a group of other males once they reached sexual maturity. This is similar to modern elephants. It is thought that there was no specific mating season for mastodons as there is with modern elephants. 
Distribution and Habitat
The American Mastodon roamed much of North America, from Florida to Alaska, and down into Mexico. It is believed that they did not extend farther south because of limitations in the vegetation they preferred. Mastodons lived in forests and woodlands, where there was abundant vegetation to consume. 
Tusk Rings
Both Mammoths and Mastodons tusks grow throughout their entire life. This process creates growth rings in the tusk, just like tree rings. These rings tell scientists about the age of the animal, and more impressively, their life story. Trees add layers of wood to the outside, but tusks grow from the inside out, so the newest layer is in the center of the tusk. This layer is shaped like a cone, so a full tusk is a bunch of “cones” stacked together. The layers are distinguishable because they grow depending how fast the tusks grow. In the summer, when there is lots of food and warm weather, the tusks grow fast because the mammoth is healthy and has extra energy to grow its tusks. In the winter, when there is less food and colder weather, tusks grow more slowly. Scientists can even see weekly or daily changes in tusk growth. Tusks show us how long a calf nursed from its mother, at what age these animals reached sexual maturity, the initiation of breeding season, or even how easy or hard it was for the animal to find food during a given time.

Fun Facts

  • Paleontologists found over 1800 individual elements of mastodon skeletons at Ziegler reservoir.
  • The American Mastodon was the most common mammal found at the Ziegler dig site. It was also the highest elevation site in North America for a mastodon. 
  • Both Mastodons and Mammoths have growth rings in their tusks just like tree rings!