Mastodon

"Mammut" redirects here. For other uses, see Mammut (disambiguation) and Mastodon (disambiguation).

Mastodon Temporal range: Late Miocene - Late Pleistocene, 5.3–0.011 Ma PreЄ Є O S D C P T J K Pg N
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Mounted M. americanum skeleton (the "Warren mastodon"), AMNH
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Order:	Proboscidea
Family:	†Mammutidae
Genus:	†Mammut Blumenbach, 1799
Type species
†Elephas americanum Kerr, 1792
Species
M. americanum (Kerr, 1792) M. matthewi Osborn, 1921 M. raki Frick, 1933 M. cosoensis Schultz, 1937
File:Mammut distribution.svg
The inferred range of Mammut
Synonyms
Mastodon Cuvier, 1817 Tetracaulodon Godman, 1830 Missourium Koch, 1840 Leviathan Koch, 1841 (Emend. Koch, 1843) Pliomastodon Osborn, 1926

Mastodons (Greek: μαστός "breast" and ὀδούς, "tooth") are any species of extinct proboscideans in the genus Mammut, distantly related to elephants, 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 fed on a mixed diet of browsing and grazing with a seasonal preference for browsing, in contrast to living elephants that are mostly grazing animals.

M. americanum, the American mastodon, is the youngest and best-known species of the genus. They disappeared from North America as part of a mass extinction of most of the Pleistocene megafauna, widely presumed to have been related to overexploitation by Clovis hunters, and possibly also to climate change.

Description

File:Mammut americanum Sergiodlarosa.jpg

Restoration

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, 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 metres (9.5 ft) tall and weight 7.8 tonnes (7.7 long tons; 8.6 short tons), and another male grew 3.25 metres (10.7 ft) tall and weighed 11 tonnes (11 long tons; 12 short tons). Another species, M. borsoni, is known from 30–40-year-old males that could grow 3.9–4.1 metres (12.8–13.5 ft) tall and weighting 14–16 tonnes (14–16 long tons; 15–18 short tons). 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.

Discovery

The first remnant of Mammut, a tooth some in weight, was discovered in the village of Claverack, New York in 1705. The mystery animal became known as the "incognitum". The first bones to be collected and studied scientifically were found in 1739 at Big Bone Lick State Park, Kentucky by French soldiers, who carried them to the Mississippi River, from where they were transported to the National Museum of Natural History in Paris. Some time later, similar remains were found in South Carolina, which, according to the slaves, looked remarkably similar to those of African elephants, soon followed discoveries of complete bones and tusks in Ohio, and people started referring to the "incognitum" as a mammoth, like the ones that were being dug out in Siberia. Anatomists noted that the teeth of mammoth and elephants were different from those of incognitum, which possessed rows of large conical cusps, indicating that they were dealing with a distinct species. In 1806, the French anatomist Georges Cuvier named the incognitum "mastodon."

Classification and species

Comparison of woolly mammoth (L) and American mastodon (R)

Mammut is a genus of the extinct family Mammutidae, related to the proboscidean family Elephantidae (mammoths and elephants) from which it originally diverged approximately 27 million years ago. The following cladogram shows the placement of the American mastodon among other proboscideans, based on hyoid characteristics:

	Mammut americanum (American mastodon) Gomphotherium sp. Stegodon zdanskyi Loxodonta africana (African elephant) Elephas maximus (Asian elephant) Mammuthus columbi (Columbian mammoth)

File:Burning Tree Mastodon excavation (mid-December 1989), Burning Tree Golf Course, Heath, east-central Ohio.jpg

Excavation of a specimen in a golf course in Heath, Ohio, 1989

Over the years, several fossils from localities in North America, Africa and Asia have been attributed to Mammut, but only the North American remains have been named and described, one of them being M. furlongi, named from remains found in the Juntura Formation of Oregon, dating from the late Miocene. However, it is no longer considered valid, leaving only four valid species.

M. matthewi: Found in the Snake Creek Formation of Nebraska, dating from the late Hemphillian. Some authors consider it practically indistinguishable from M. americanum.

M. raki: Its remains were found in the Palomas Formation, nearby Truth or Consequences, New Mexico, dating from the early-middle Pliocene, between 4.5-3.6 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 don't consider it sufficiently distinct from M. americaum to warrant its own species.

M. cosoensis: Found in the Coso Formation of California, dating from the late Pliocene, originally a species of Pliomastodon it was later assigned to Mammut.

M. americanum: The American mastodon, the best known and the last species of Mammut, its earliest occurrences date from the early-middle Pliocene (early Blancan stage). It had a continent wide distribution, especially during the Pleistocene epoch, known from fossil sites ranging from present-day Alaska and New England in the north, to Florida, southern California, and as far south as Honduras. The American mastodon resembled a woolly mammoth in appearance, with a thick coat of shaggy hair. It had tusks that sometimes exceeded five meters 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.

A complete mtDNA sequence has been obtained from the tooth of an M. americanum skeleton found in permafrost in northern Alaska. The remains are thought to be 50,000 to 130,000 years old. This sequence has been used as an outgroup to refine divergence dates in the evolution of the Elephantidae. The rate of mtDNA sequence change in proboscideans was found to be significantly lower than in primates.

Etymology

File:Mastodon teeth.jpg

American mastodon molars at the State Museum of Pennsylvania

The name mastodon (or mastodont) means "breast tooth" (Ancient Greek: μαστός "breast" and ὀδούς, "tooth"), and was assigned by the French naturalist Georges Cuvier in 1817, for the nipple-like projections on the crowns of its molars.

Mastodon as a genus name is obsolete; the valid name is Mammut, a name that preceded Cuvier's description, making Mastodon a junior synonym. The change was met with resistance, and authors sometimes applied "Mastodon" as an informal name so it became the common term for members of the genus.

Paleobiology

Social behavior

File:La Brea Mastodons.jpg

Female and calf American mastodon at the George Page Museum

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

Range and habitat

File:Knight Mastodon.jpg

Restoration of a herd by Charles R. Knight

The 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 faunal stages of Blancan to Rancholabrean and in location 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.

Diet

Mastodons have been characterized as predominantly browsing animals. Most accounts of gut contents have identified coniferous twigs as the dominant element in their diet. Other accounts (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.

Extinction

They are generally reported as having disappeared from North America about 10,500 years ago as part of a mass extinction of most of the Pleistocene megafauna, widely presumed to have been as a result of human hunting pressure. The latest Paleo-Indians entered the American continent and expanded to relatively large numbers 13,000 years ago, and their hunting may have caused a gradual attrition of the mastodon population. Analysis of tusks of mastodons from the American Great Lakes region over a span of several thousand years prior to their extinction in the area shows a trend of declining age at maturation; this is contrary to what one would expect if they were experiencing stresses from an unfavorable environment, but is consistent with a reduction in intraspecific competition that would result from a population being reduced by human hunting.

See also

• Coats-Hines Site
• List of museums and colleges with mastodon fossils on display
• Manis Mastodon Site
• Snowmastodon Project

External links

• The Rochester Museum of Science - Expedition Earth Glaciers & Giants
• Illinois State Museum - Mastodon
• Calvin College Mastodon Page
• American Museum of Natural History - Warren Mastodon
• BBC Science and Nature:Animals - American mastodon Mammut americanum
• BBC News - Greek mastodon find 'spectacular'
• Paleontological Research Institute - The Mastodon Project
• Missouri State Parks and Histroric Sites - Mastodon State Historic Site
• Saint Louis Front Page - Mastodon State Historic Site
• Story of the Randolph Mastodon (Earlham College)
• The Florida Museum of Natural History Virtual Exhibit - The Aucilla River Prehistory Project:When The First Floridians Met The Last Mastodons
• Worlds longest tusks
• Western Center for Archaeology & Paleontology, home of the largest mastodon ever found in the Western United States
• Smithsonian Magazine Features Mammoths and Mastodons
• 360 View of Mastodon Skull from Indiana State Museumar:الصناجة