More about Mastodons
(Mammut americanum)

The American mastodon (Mammut americanum) is one of the most celebrated and best known fossil mammals of the Pleistocene Epoch. Its fossils have been collected in the thousands and several complete or nearly complete skeletons have been recovered. Some remarkable specimens have even preserved hair and internal organs.

p.Ventral view of skull
(after Godman, 1826)

American mastodons are sometimes confused with their distant relatives, mammoths and elephants. All of them have or had well-developed trunks and tusks, but the mastodons were shorter in height, longer in length and more heavily built. The head was larger, but lacked the distinctive "hump" at the crest that is found in the Indian elephant and mammoths. In addition, the mastodon's head was carried horizontally, whereas those of the elephants and mammoths are or were angled down. Preserved hair from one eastern locality indicates that it had a coat of fine wool overlain with long, coarse guard hairs.

The tusks were generally larger and longer than those of modern elephants, but conspicuously less curved than those of mammoths. They extended horizontally from the skull and curved outwards and then inwards. Young males often had a second, short pair of tusks extending from the lower jaw, but these were lost by maturity (1).

p.Lower jaw fragment with molars
(after Cuvier, 1825)

The most distinct and diagnostic feature of mastodons is their grinding teeth (molars and premolars). Because of their distinctive anatomy, impressive size and durability, molars are typically the most commonly collected of mastodon fossils. These teeth, which are more primitive than those of elephants and mammoths, have pairs of large cusps (knobs) covered by dense enamel. A mastodon had a total six teeth on each side of the jaw during its lifetime (a total of 24 teeth for both sides of the upper and lower jaws). Worn teeth in the front of the jaw were replaced by teeth growing in from the back. Young animals had three teeth on each jaw, but most mature individuals usually only had two and old individuals often had only one.

The American mastodon was an adaptable, wide-ranging, and long-lived species; it exhibited remarkably little variation over time or space. It was restricted to North America, but its remains have been found from Alaska and northern Canada to Honduras and from coast to coast; mastodon fossils have even been collected in fishermen's nets as much as 180 miles (300 km) off the eastern coast of the United States. (2) The earliest records date from 3.7 million years ago (Pliocene). It's generally accepted that this species went extinct between 12,000 and 9,000 years ago.

Fossils are most frequent in the eastern United States and the Great Lakes Region, which were covered by spruce forests and open spruce woodlands during the Pleistocene. Elsewhere, mastodons probably favored forested valleys, lowlands and swamps. Its teeth were well suited for browsing on trees and shrubs, and its tusks may have been used for removing branches. Analysis of undigested plant remains revealed that they fed on a variety of plant types, but conifer needles were typically the most frequent food item.

Most fossils represent single individuals, which has led many researchers to infer that, unlike elephants and mammoths, adult mastodons were solitary. However, the existence of a few mass-mortality sites suggests that it was a social animal. In addition, age studies indicate that mastodons took about 10 years to reach maturity. This interval, which is longer than those of modern elephants, would require extended parental care that is often provided by cohesive herds.

p.Molar of Mammut borsoni
(after Buffon, 1778)

The American mastodon is a member of the family Mammutidae. The earliest known member of the family has been collected from 35 million year old deposits in North Africa. Members spread into Eurasia about 20 million years ago and entered Beringia (eastern Siberia, Alaska and Yukon) about 15 million years ago. Several members of this family have been recorded in North America, but the American mastodon is the only species present in the late Pliocene and Pleistocene. A close relative, Mammut borsoni, inhabited Europe about 3 million years ago (late Pliocene) (3).

Mastodons belong to the Order Proboscidea. A group of mammals characterized by the possession of trunks, tusks (on the upper and/or lower jaws) and heavy bodies. They originated in Africa and extended into Eurasia and the Americas. In addition to the American mastodon, several other proboscideans inhabited North America in the late Pleistocene. Two species of gomphotheres, Cuvieronius tropicus and Haplomastodon waringi (f4), were characteristic of the South American fauna, but extended into the southern part of the North America. Several species of mammoths were also present in the North American Pleistocene. One of these, the woolly mammoth (Mammuthus primigenius) was also found at Big Bone Lick.

The proboscideans were a diverse and successful group of large mammals. Currently, however, they are represented by only three species, the African elephant (Loxodonta africana), the forest African elephant (Loxodonta cyclotis) and the Indian elephant (Elephas maximus).