Related Biomes
Jeffersonian Mammoth
Jeffersonian Mammoth, Mammuthus jeffersonii
Approximately 1.5 to 1.8 million years ago the first mammoths entered North America. These mammoths came from Eurasia, crossing the Bering Strait at a time when sea level was lower than today. The first mammoths from Eurasia belonged to a species called M. meridionalis. The descendants of this species of mammoth included both Columbian and Jeffersonian mammoths.
Until recently, scientists recognized four species of mammoths (genus Mammuthus) during the late Pleistocene in North America. These were the Columbian mammoth (M. columbi), Jeffersonian mammoth (M. jeffersonii), woolly mammoth (M. primigenius), and the island pygmy mammoth (M. exilis) who lived on the Channel Islands off the coast of California. These species are defined primarily on differences in the morphology of their teeth and skeletons. However, recent genetic work on Columbian mammoths in Utah and Wyoming indicate a close relationship to woolly mammoths in Alaska, suggesting that, despite relatively large morphological differences between the two species of mammoths, genetically they were very similar (Enk et al 2011).
The Midwest was home to two species of mammoths, Jeffersonian and Woolly mammoths. Approximately 13,000 years ago all species of mammoths went extinct in North America. Mammoths, mastodons and modern elephants, are members of the order Proboscidea. The mammoths are closely related to the living elephants, especially to the Asian elephant (Elephas maximus).
Reconstructed Jeffersonian mammoth skeleton from Kewanee, Illinois. On display at the University of Nebraska State Museum, Lincoln, Nebraska.
Height: 3.0-3.7 m (10-12 ft)
Weight: 5500-7300 kg (6-8 tons)
Physical Description:
Mammoths were large members of the family Elephantidae. Unlike Woolly Mammoths, there are no mummified remains of Jeffersonian mammoths, so details of their outward appearance are unknown. Their presence in Midwestern loess deposits dating to the Last Glacial Maximum suggests some degree of cold-adaptation, similar to Woolly Mammoths; so it is likely that they had a thick coat of hair. Long, coarse hairs found in western cave deposits (Bechan Cave, Utah; Cowboy Cave, Utah; Pendejo Cave, New Mexico) suggests that the closely related Columbian mammoth had hair similar to its woolly cousins, although it is unknown how thick its coat may have been. Modern elephants are not very sensitive to temperature swings and to not exhibit discomfort in temperatures below freezing, nor do they grow longer hair in those conditions.
Mammoths, like modern elephants, have elongated upper incisors in the form of tusks. Tusks are large, heavy parts of the animal. Average sized tusks can weigh more than 350 pounds. Elements of this size require support in the form of additional robustness of the skull and axial skeleton. The skull and mandible of the Jeffersonian mammoth is longer, with a less pronounced forehead than the woolly mammoth. Although there is overlap in dental traits, the last upper molars of Jeffersonian mammoths are longer and more slender than their woolly counterparts, with more plates per tooth than the Columbian mammoth. The last lower molar is wider with less plate compression than woolly mammoths. Post-cranial elements of the skeleton are difficult to distinguish between different mammoth species. Like many large mammals, Mammoths show sexual dimorphism between males and females. The body size of bull mammoths may be up to 20% larger than females of the same age.
Jeffersonian mammoths occur throughout the eastern Great Plains and Midwest, although there are occasional records in the desert southwest and southeastern US (Saunders 1970). As with the Columbian mammoth to the west, scientists think that M. jeffersonii preferred an open, grassland habitat. Most midwestern records of this mammoth indicate a presence from the last interglacial, about 130,000 years ago, to the last glacial maximum, about 18,000 years ago. Midwestern environments during this time would have included relatively cold, arid habitats, including forest tundra, and spruce parkland.
Since the Jeffersonian mammoth has been found primarily in localities representative of cold, relatively open environments, it is likely that this species of mammoth had a diet dominated by cool-season grasses and sedges. This is supported by a limited dataset of stable carbon isotopes on M. jeffersonii bone collagen (Saunders et al. 2010).
Jeffersonian mammoths were primarily distributed throughout eastern northern North America, although there are outliers in the Great Plains and Southwest (Saunders 1970). This species probably split from the M. columbi lineage earlier. Excellent examples of M. jeffersonii are present in freshwater spring deposits from western Missouri dating to the last inter-glacial (75,000-130,000 BP; Saunders 1988). Although few specimens have been directly dated, Jeffersonian mammoths continued to roam the Midcontinent until at least the Last Glacial Maximum (18-24,000 BP). Two of these mammoths are present in Peoria loess deposits in western Illinois, at Principia College (Jersey County, Illinois) and Belleview (Calhoun County, Illinois) (Saunders et al. 2010).
Jeffersonian mammoths were extinct in the Midwest at the end of the last glacial maximum. The youngest dated specimen is late glacial in age (~19,000 years ago) and is a tooth from Bureau County, Illinois, near Wyanet (Pasenko and Schubert 2004).
In many ways, mammoths are anatomically similar to modern elephants. Some of these features are a function of their large body size. For instance, body temperature can vary by a few degrees in different parts of the body. Although their internal organs are not proporationally larger than smaller animals, the heart of mammoths has a bifid (double-pointed) apex, unlike humans.
The Principia Mammoth: https://content.principia.edu/sites/mammoth/
Pasenko, M. R. and B. W. Schubert. "Mammuthus jeffersonii (Proboscidea, Mammalia) from Northern Illinois" (2004). Paleobios 24:19-24.
Saunders, J., 1970. The Distribution and Taxonomy of Mammuthus in Arizona. MA Thesis, Department of Geosciences, University of Arizona, Tucson.
Saunders, J. 1988. Fossiliferous spring sites in southwestern Missouri. Bulletin of the Buffalo Society of Natural Sciences, 33, 127-140.
Saunders, Jeffrey J., et al. "Paradigms and proboscideans in the southern Great Lakes region, USA." Quaternary International 217.1 (2010): 175-187.
Treworgy, J. D., J. Saunders, and D. A. Grimley. "Mammoth (Mammuthus sp.) excavation on a college campus in Western Illinois, USA."Quaternary International 169 (2007): 24-28.
Related Animals:
