Mastodon

Mastodon
Mounted Mammut americanum skeleton. Mounted Mammut americanum skeleton.
Conservation status
Prehistoric
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Proboscidea Family: Mammutidae Hay, 1922
Species of Mammutgenus
Mammut americanum Mammut borsoni

Mastodon is the common name for any of the large, extinct elephant-like mammals comprising the family Mammutidae (syn. Mastodontidae) of the order Proboscidea, characterized by long tusks, large pillar-like legs, and a flexible trunk, or proboscis. Although similar to elephants (family Elephantidae, including mammoths, mastodons belong to a different family of proboscidians, and have molar teeth of a different structure. They also are known as mastodonts. Sometimes references to mastodons are limited to the genus Mammut (syn Mastodon).

Mastodons lived from about the Oligocene of the Paleogene period, about 30 million years ago, until about 10,000 years ago, when the only known North American species, the American mastodon (Mammut americanum) died out. This well-known species is a close relative of the Borson's mastodon (Mammut borsoni) that lived in Europe.

The name comes from the Greek μαστός and οδούς, meaning "nipple tooth," reflecting the distinctive, cone-like cusps or nipple-like protrusions on the crowns, which would have been more conducive to browsing on trees, shrubs, and swamp plants than grazing on grasses as with the mammoths and their flatter, ridged teeth (Dykens and Gillette, BBC 2008).

Overview and description

Life restoration of Mammut americanum.

Mastodons belong to the mammalian order Proboscidea. Today, only the elephant family, Elephantidae, includes extant (living) species. Mastodons belong to another proboscidean family, Mammutidae (syn. Mastodontidae). The mammoths are another extinct group that overlapped in time with the mastodons, also dying out about 10,000 years ago, but they also belonged to the Elephantidae family, as the genus Mammuthus. Altogether, paleontologists have identified about 170 fossil species that are classified as belonging to the Proboscidea, with the oldest dating from the early Paleocene epoch of the Paleogene period over 56 million years ago. Mastodons first appear in Northern Africa in the Oligocene of the Paleogene period about 30 million years ago, while Primelephas, the ancestor of mammoths and modern elephants, appeared in the late Miocene epoch, about 7 million years ago.

Mastodons, like elephants, are large, heavy mammals with tusks and flexible tusks. Their skulls tended to be larger than those of mammoths, and the American mastodon (Mammut americanum) has low-domed heads unlike the higher-domed heads of mammoths and modern-day Asian elephants (Dykens and Gillette). The skeleton of mastodons was stockier and more robust (Kurtén and Anderson 1980, p. 345). Mastodons also seem to have lacked the undercoat characteristic of mammoths (Kurtén and Anderson 1980, p. 345).

Mastodons differed from mammoths primarily in the blunt, conical, nipple-like projections on the crowns of their molars, which were more suited to chewing leaves than the high-crowned teeth mammoths used for grazing. Thus, the name mastodon, which means "nipple teeth," became both their common name and an obsolete name for their family (Mastodontidae) and the genus Mastodon (Agusti and Mauricio 2002). In contrast, mammoths, and elephants, whose molars were large, complex, specialized structures, had molars that were more flat and had low ridges of dense enamel on the surface (ANS). Mastodons are thought to have been browsers, while mammoths were grazers.

The American mastodon tended to be about 2.1 meters (7 feet) in height for females and 3.1 meters (10 feet) in height for the males, with adult mastodons weighing as much as 5500 kilograms (6 tons)(Dykens and Gillette). This is smaller than the imperial mammoth of North America, which reached great size, being up to at least 5 meterss (16 feet) at the shoulder (ANS). It also is smaller than the largest group of extant elephants, the African elephants, which are up to 3.9 meters (13 feet) tall. It is about the size of woolly mammoths, which had about the same height (2.8 to 3.4 meters, or 9 to 11 feet) and weight (4 to 6 tons) as the Asian elephants (ANSP).

Mastodon tusks tended to be less curved than mammoths, but longer and larger than those of modern elephans (Dykens and Gillette). The tusks of the American mastodon sometimes exceeded five meters in length and were nearly horizontal, in contrast with the more curved mammoth tusks (Kurtén and Anderson 1980). Young males had vestigial lower tusks that were lost in adulthood (Kurtén and Anderson 1980). However, it has been proven that female American mastodons had lower pairs of tusks.

The tusks of American mastodons were probably used to break branches and twigs, although some evidence suggests males may have used them in mating challenges; one tusk is often shorter than the other, suggesting that, like humans and modern elephants, mastodons may have had laterality (Kurtén and Anderson 1980). Examination of fossilized tusks revealed a series of regularly spaced shallow pits on the underside of the tusks. Microscopic examination showed damage to the dentin under the pits. It is theorized that the damage was caused when the males were fighting over mating rights. The curved shape of the tusks would have forced them downward with each blow, causing damage to the newly forming ivory at the base of the tusk. The regularity of the damage in the growth patterns of the tusks indicates that this was an annual occurrence, probably occurring during the spring and early summer (Fisher 2006).

Distribution and habitat

The Exhumation of the Mastodon by Peale

Fossils of the American mastodon (Mammut americanum) have been found across all of the North America, from Alaska to central Mexico, and on the eastern seaboard (Dykens and Gillette). Other species of mastodon were widely distributed throughout the world, with fossils found common and well-preserved in Pliocene and Pleistocene age deposits.

Though their habitat spanned a large territory, American mastodons were most common in the ice age spruce forests of the eastern United States, as well as in warmer lowland environments (Kurtén and Anderson, 1980). Their remains have been found as far as 300 kilometers offshore of the northeastern United States, in areas that were dry land during the low sea level stand of the last ice age (Kurtén and Anderson 1980). Mastodon fossils have been found in South America; on the Olympic Peninsula of Washington state, USA (Manis Mastodon Site) (Kirk and Daugherty 2007); in Kentucky (particularly noteworthy are early finds in what is now Big Bone Lick State Park); the Kimmswick Bone Bed in Missouri; in Stewiacke, Nova Scotia, Canada; in Richland County, Wisconsin; in La Grange, Texas; and north of Fort Wayne, Indiana, USA.

Appearance and extinction

Mastodons first appear in Northern Africa in the Oligocene of the Paleogene period about 30 million years ago. Members of the

Members of the Mammut (Mastodon) genus are thought to have first appeared almost four million years ago. They were native to both Eurasia and North America but the Eurasian species Mammut borsoni died out approximately three million years ago. Fossils of this species have been found in England, Germany, the Netherlands, and northern Greece. Mammut americanum, the American mastodon, disappeared from North America about 10,000 years ago (BBC 2007), at the same time as most other Pleistocene megafauna.

The cause for the extinction of the American mastodon is unknown. Recent studies indicate that tuberculosis may have been partly responsible for the extinction of the mastodon 10,000 years ago (Johnson 2006). Another influencing factor to their eventual extinction in America during the late Pleistocene may have been the presence of Paleo-indians, which entered the American continent in relatively large numbers 13,000 years ago. Their hunting caused a gradual attrition to the mastodon and mammoth populations, significant enough that over time the mastodons were hunted to extinction (Ward 1997).

References

ISBN links support NWE through referral fees

• Academy of Natural Sciences, Philadelphia (ANSP). n.d. American mastodon (Mammut americana). Academy of Natural Sciences. Retrieved May 16, 2008.

• Agusti, J., and M. Anton. 2002. Mammoths, Sabretooths, and Hominids. New York: Columbia University Press. ISBN 0231116403.

• British Broadcasting Corporation (BBC). 2008. American mastodon, Mammut americanum. BBC. Retrieved May 16, 2008.

• British Broadcasting Corporation (BBC). 2007. Greek mastodon find "spectacular". BBC July 24, 2007. Retrieved May 16, 2008.

• Dykens, M., and L. Gillette. n.d. Mammut americanum American mastodon. San Diego History Museum. Retrieved May 16, 2008.

• Fisher, D. 2006. Tusk cementum defects record musth battles in American mastodons. Sixty-Sixth Annual Meeting of the Society of Vertebrate Paleontology, Oct. 18-21, 2006.

• Johnson, K. 2006. Mastodons driven to extinction by tuberculosis, fossils suggest. National Geographic News October 3, 2006. Retrieved May 16, 2008.

• Kirk, R., and R. D. Daugherty. 2007. Archaeology in Washington. Seattle: University of Washington Press. ISBN 9780295986975.

• Kurtén, B., and E. Anderson. 1980. Pleistocene Mammals of North America. New York: Columbia University Press. ISBN 0231037333.

• Ward, P. D. 1997. The Call of Distant Mammoths: Why the Ice Age Mammals Disappeared. New York: Copernicus. ISBN 0387949151.

External links

• http://www.museum.state.il.us/exhibits/larson/mammut.html Retrieved May 16, 2008.
• http://www.amnh.org/exhibitions/expeditions/treasure_fossil/Treasures/Warren_Mastodon/warren.html?acts Retrieved May 16, 2008.
• http://www.priweb.org/mastodon/mastodon_home.html Retrieved May 16, 2008.
• http://www.mostateparks.com/mastodon.htm Retrieved May 16, 2008.
• http://www.slfp.com/Mastodon.htm Retrieved May 16, 2008.
• http://www.flmnh.ufl.edu/exhibits Retrieved May 16, 2008.

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