Mastodon

Karen Carr Artwork

A **mastodon** (Greek: μαστός "breast" and ὀδούς, "tooth") is any proboscidean belonging to the extinct genus Mammut (family Mammutidae) that inhabited North and Central America during the late Miocene  or late Pliocene  up to their extinction at the end of the Pleistocene 10,000 to 11,000 years ago. Mastodons lived in herds and were predominantly forest-dwelling animals that lived on a mixed diet obtained by browsing and grazing, somewhat similar to their distant relatives, modern elephants, but probably with greater emphasis on browsing.

The American mastodon (*M. americanum*), and the Pacific mastodon (*M. pacificus*), are the youngest and best-known species of the genus. Mastodons disappeared from North America as part of a mass extinction of most of the Pleistocene megafauna, widely believed to have been caused by a combination of climate changes at the end of the Pleistocene combined with overexploitation by Clovis hunters.

Compared to mammoths, mastodons had shorter legs, a longer body and were more heavily muscled, a build similar to that of the current Asian elephants. The average body size of the American mastodon was around 2.3 m (7 ft 7 in) in height at the shoulders, corresponding to a large female or a small male, but large males could grow up to 2.8 m (9 ft 2 in) in height and weigh as much as 4.5 tonnes (5 short tons). However, the 35-year-old specimen AMNH 9950 could grow 2.89 meters (9.5 ft) tall and weighed 7.8 tonnes (7.7 long tons; 8.6 short tons), and another male grew 3.25 meters (10.7 ft) tall and weighed 11 tonnes (11 long tons; 12 short tons). Another species, the Borson's mastodon (*M. borsoni*) (although it may actually be a species of the genus *Zygolophodon*), is known from 30–40-year-old males that were 3.9–4.1 meters (12.8–13.5 feet) tall and 14–16 tons (14–16 long tons; 15–18 short tons) in weight. Like modern elephants, the females were smaller than the males. They had a low and long skull with long curved tusks, with those of the males being more massive and more strongly curved. Mastodons had cusp-shaped teeth, very different from mammoth and elephant teeth (which have a series of enamel plates), well-suited for chewing leaves and branches of trees and shrubs.

## Distribution and Habitat

Range of most species of Mammut is unknown as their occurrences are restricted to few localities, the exception being the American mastodon (M. americanum), which is one of the most widely distributed Pleistocene proboscideans in North America. M. americanum fossil sites range in time from the Blancan to Rancholabrean faunal stages and in locations from as far north as Alaska, as far east as Florida, and as far south as the state of Puebla in central Mexico, with an isolated record from Honduras, probably reflecting the results of the maximum expansion achieved by the American mastodon during the Late Pleistocene. A few isolated reports tell of mastodons being found along the east coast up to the New England region, with high concentrations in the Mid-Atlantic region. There is strong evidence indicating that the members of Mammut were forest dwelling proboscideans, predominating in woodlands and forests, and browsed on trees and shrubs. They apparently did not disperse southward to South America, it being speculated that this was because of a dietary specialization on a particular type of vegetation. The Largest known specimens of Mammut were known as Giant Mastodons, which had a size of 10-13 tons. They included Mammut/Zygolophodon Borsoni from Pliocene Eurasia(mainly Greece, the Iberian Peninsula, Romania, & even China), formerly known as the “Borson’s Mastodon”, & an unknown species of Mammut from the Gray Fossil Site in Tennessee, which was dubbed as the “Tennessee Giant Mastodon”.

## Taxonomy

Mastodon as a genus name is obsolete; the valid name is Mammut, as that name preceded Cuvier's description, making Mastodon a junior synonym. The change was met with resistance, and authors sometimes applied "Mastodon" as an informal name; consequently it became the common term for members of the genus. "Mastodon" is also used informally to describe other non-elephant proboscideans, such as gomphotheres.

Species include:

* M. americanum, the American mastodon, is one of the best known and among the last species of Mammut. Its earliest occurrences date from the early-middle Pliocene (early Blancan stage). It was formerly regarded (see below) as having a continent-wide distribution, especially during the Pleistocene epoch, known from fossil sites ranging from present-day Alaska, Ontario and New England in the north, to Florida, and as far south as Honduras. Environmental DNA also suggests they ranged as far northeast as Greenland during the warmer conditions of the early Pleistocene. It had tusks that sometimes exceeded 5 m (16 ft) in length; they curved upwards, but less dramatically than those of the woolly mammoth. Its main habitat was cold spruce woodlands, and it is believed to have browsed in herds. It became extinct at the end of the Pleistocene approximately 11,000 years ago.
* M. matthewi — found in the Snake Creek Formation of Nebraska, dating to the late Hemphillian (Late Miocene-Early Pliocene). Some authors consider it practically indistinguishable from M. americanum.
* M. pacificus — based on a 2019 analysis, Pleistocene specimens from California and southern Idaho have been transferred from M. americanum to this new species. It differs from the eastern population in having narrower molars, six as opposed to five sacral vertebrae, a thicker femur, and a consistent absence of mandibular tusks.
* M. raki — Its remains were found in the Palomas Formation, near Truth or Consequences, New Mexico, dating from the early-middle Pliocene, between 4.5 and 3.6 Ma. It coexisted with Equus simplicidens and Gigantocamelus and differs from M. americanum in having a relatively longer and narrower third molar, similar to the description of the defunct genus Pliomastodon, which supports its arrangement as an early species of Mammut. However, like M. matthewi, some authors do not consider it sufficiently distinct from M. americanum to warrant its own species.
* M. cosoensis — found in the Coso Formation of California, dating to the Late Pliocene, originally a species of Pliomastodon, it was later assigned to Mammut.
* M. furlongi, known from a partial mandible with three preserved molars (m1-m3) and a referred m3 from the Clarendonian of Oregon, originally placed in Pliomastodon.
* M. nevadanus originally placed in Pliomastodon, based on a partial cranium with preserved molars and a right tusk from Thousand Creek beds of Humboldt County, Nevada, dating to the Late Miocene-Early Pliocene (Hemphillian) unlike M. americanum, the tusk cuves downwards.
* "M." borsoni known from the late Miocene to Early Pleistocene of Europe and China, one of the largest known proboscideans, its placement in the genus is equivocal, as its relationship with North American Mammut is unclear.

### Evolution

Mammut is a genus of the extinct proboscidean family Mammutidae, related to the family Elephantidae (mammoths and elephants), from which it originally diverged approximately twenty-seven million years ago. The following cladogram shows the placement of the American mastodon among other proboscideans, based on hyoid characteristics:

Mammutids originated in Africa during the Late Oligocene, with the oldest member of the family, Losodokodon known from deposits in Kenya approximately 24-27 million years old. Mammutids expanded into Eurasia during the Early Miocene, approximately 18 million years ago, following the collision between the two landmasses.
Mammutids, represented by Zygolophodon, first arrived in North America across the Bering Land Bridge during the late early Miocene, approximately 16.5 million years ago. Mammut is thought to have evolved from Zygolophodon, though the relationship between North American Mammut and some Eurasian species assigned to the genus, such as the Late Miocene-earliest Pleistocene species "Mammut" borsoni is uncertain. Authors have proposed various hypotheses, including a second migration of mammutids into North America during the Late Miocene-Pliocene with the North American Mammut being descended from Eurasian Mammut species, or that the Eurasian and North American species of Mammut are not closely related and evolved in parallel. The second migration hypothesis has been criticised for lacking supporting evidence.

## Description

Modern reconstructions based on partial and skeletal remains reveal that mastodons were very similar in appearance to elephants and, to a lesser degree, mammoths, though not closely related to either one. Compared to mammoths, mastodons had shorter legs, a longer body and were more heavily muscled, a build similar to that of the current Asian elephants. The average body size of the species M. americanum was around 2.3 m (7 ft 7 in) in height at the shoulders, corresponding to a large female or a small male; large males were up to 2.8 m (9 ft 2 in) in height. Among the largest male specimens, the 35-year-old AMNH 9950 was 2.89 m (9.5 ft) tall and weighed 7.8 tonnes (7.7 long tons; 8.6 short tons), while another was 3.25 m (10.7 ft) tall and weighed 11 tonnes (11 long tons; 12 short tons).

American mastodon molars at the State Museum of Pennsylvania
Like modern elephants, the females were smaller than the males. They had a low and long skull with long curved tusks, with those of the males being more massive and more strongly curved. Mastodons had cusp-shaped teeth, very different from mammoth and elephant teeth (which have a series of enamel plates), well-suited for chewing leaves and branches of trees and shrubs.

## Paleobiology

### Social behavior

Based on the characteristics of mastodon bone sites and strontium and oxygen isotopes from tusks, it can be inferred that, as in modern proboscideans, the mastodon social group consisted of adult females and young, living in bonded groups called mixed herds. The males abandoned the mixed herds once reaching sexual maturity and lived either alone or in male bond groupings. As in modern elephants, there probably was no seasonal synchrony of mating activity, with both males and females seeking out each other for mating when sexually active.

### Diet

Mastodons have been characterized as predominantly browsing animals. Of the New World proboscideans, they appear to have been the most consistent in browsing rather than grazing, consuming C3 as opposed to C4 plants, and in occupying closed forests versus more open habitats. This dietary inflexibility may have prevented them from invading South America during the Great American Interchange, due to the need to cross areas of grassland to do so. Most accounts of gut contents have identified coniferous twigs as the dominant element in their diet. Other accounts (e.g., the Burning Tree mastodon) have reported no coniferous content and suggest selective feeding on low, herbaceous vegetation, implying a mixed browsing and grazing diet, with evidence provided by studies of isotopic bone chemistry indicating a seasonal preference for browsing. Study of mastodon teeth microwear patterns indicates that mastodons could adjust their diet according to the ecosystem, with regionally specific feeding patterns corresponding to boreal forest versus cypress swamps, while a population at a given location was sometimes able to maintain its dietary niche through changes in climate and browse species availability. Mastodons have been found to have been eating pumpkins along with species like woolly mammoths and other elephant species at the time. The pumpkin would have been too toxic for many animals but mastodons are able to avoid their toxicity due to their large body size. Mastodons also distributed pumpkin seeds around the place aiding in pumpkin range expansion.

## Extinction

It is believed that the American Mastodon went extinct due to change in climate and human hunting. The American mastodon went extinct at the end of the Pleistocene during the Quaternary extinction event.

## Appearance in other media

### *Jurassic Park*

* In a couple video games, Jurassic World: The Game and Jurassic Park Builder