Temporal range: Late Pleistocene to Early Holocene, 0.013–0.011Ma
|Composite male skeleton in the Page Museum at the La Brea Tar Pits, Los Angeles|
The Columbian mammoth (Mammuthus columbi) was a species of mammoth, the common name for the extinct elephant genus Mammuthus. The Columbian mammoth was one of the last in a line of mammoth species, beginning with Mammuthus subplanifrons in the early Pliocene. M. columbi diverged from the steppe mammoth, M. trogontherii, about 200,000 years ago in eastern Asia. Its closest extant relative is the Asian elephant.
It lived in the Quaternary period and appeared in North America (in the present United States and to as far south as Nicaragua and Honduras) during the late Pleistocene. It had long, curved tusks and four molars, which were replaced six times during the lifetime of an individual. Its behaviour was similar to that of modern elephants, and it used its tusks and trunk for manipulating objects, fighting, and foraging.
The Columbian mammoth reached 4 m (13 ft) at the shoulders, and it weighed up to about 10 tonnes.
The Columbian mammoth was first scientifically described by Scottish naturalist Hugh Falconer in 1857, based on a partial upper molar found during the excavation of the Brunswick Altamaha Canal in Georgia in the south eastern United States.
American mammoths were classified in many different genera until the start of the 20th century. Larry Agenbroad, a respected researcher, believes that M. imperator is a non-valid name given to unusually large M. columbi. Given that proboscidean tusks grow throughout the animal's life, older animals will tend to have longer tusks, which are more likely to cross. He has also mooted the alternative interpretation that M. imperator represents a subspecies of large M. columbi. This has also been accepted by other scientists.
The earliest known proboscideans, the clade that contains the elephants, existed about 55 million years ago around the Tethys Sea area. The closest living relatives of the Proboscidea are the sirenians and the hyraxes. The family elephantidae existed six million years ago in Africa, and includes the living elephants and the mammoths. Among many now extinct clades, the mastodon is only a distant relative of the mammoths, and part of the distinct family Mammutidae, which diverged 25 million years before the mammoths evolved. The following cladogram shows the placement of the Columbian mammoth among other proboscideans, based on hyoid characteristics:
Since many remains of each species of mammoth are known from several localities, it is possible to reconstruct the evolutionary history of the genus through morphological studies. Mammoth species can be identified from the number of enamel ridges (or plates) on their molars; primitive species had few ridges, and the number increased gradually as new species evolved and replaced the preceding ones. The crowns of the teeth lengthened and the skulls became taller to accommodate this. At the same time, the skulls became shorter from front to back to minimise the weight. These adaptations were acquired gradually as mammoths turned to more abrasive food items.
The first known members of the genus Mammuthus are the African species M. subplanifrons from the Pliocene, and M. africanavus from the Pleistocene. The former is thought to be the ancestor of later forms. Mammoths entered Europe around 3 million years ago. The earliest type known from there has been named M. rumanus, which spread across Europe and China. Only its molars are known, which show that it had 8–10 enamel ridges. A population evolved 12–14 ridges, splitting off from and replacing the earlier type, becoming M. meridionalis. In turn, this species was replaced by the steppe mammoth, M. trogontherii, with 18–20 ridges, which evolved in eastern Asia c. 1 million years ago. Mammoths derived from M. trogontherii evolved molars with 26 ridges 200,000 years ago in Siberia and became the woolly mammoth, M. primigenius. The Columbian mammoth, M. columbi, evolved from a population of M. trogontherii that had entered North America, and retained similar molars. A 2011 genetic study showed that two examined specimens of the Columbian mammoth were grouped within a subclade of woolly mammoths. This suggests that the two populations interbred and produced fertile offspring. A North American form known as M. jeffersonii may be a hybrid between the two species.
A 2014 study concluded that asphalt may degrade DNA of animals deposited in it, after attempting to extract DNA from a Columbian mammoth from the La Brea tar Pits.
The shoulder height of the Columbian mammoth reached 4 m (13 ft), and it weighed up to about 10 tonnes, which is equal to the weight of 130 adult humans. This is larger than modern African elephants and the woolly mammoth, which reach about 2.7 to 3.4 m (9–11 ft). Female mammoths were smaller and more lighter built than males. Soft tissue of Columbian and other mammoths is not known, so much less is known about their appearance than that of the woolly mammoth. They lived in warmer habitats than the woolly mammoth, so they probably lacked many of the adaptations seen in that species. The tail of the Columbian mammoth was intermediate in length between that of modern elephants and the woolly mammoth.
Hair believed to have belonged to the Columbian mammoth has been discovered in the Bechan Cave, Utah, where mammoth dung has also been found. Some of this hair is coarse, and identical to that known to belong to woolly mammoths. Since this location is so far south, it is unlikely that the hair belonged to woolly mammoths. The distribution and density of this fur on the living animal is unknown.
Columbian mammoths had very long tusks, which were more curved than those of modern elephants. The largest known mammoth tusk belonged to a Columbian mammoth and is 4.9 metres (16 ft) long. Others range between 3.5 metres (11 ft) and 4.121 metres (13.52 ft) long, and Columbian mammoth tusks were usually not much larger than those of woolly mammoths, which reached 4.2 metres (14 ft). The tusks of females were much smaller and thinner. About a quarter of the length was inside the sockets. The tusks grew spirally in opposite directions from the base and continued in a curve until the tips pointed towards each other, sometimes crossing. In this way, most of the weight would have been close to the skull, and there would be less torque than with straight tusks. The tusks were usually asymmetrical and showed considerable variation, with some tusks curving down instead of outwards and some being shorter due to breakage. Columbian mammoth tusks were generally less twisted than those of woolly mammoths. Calves developed small milk tusks a few centimetres long at six months old, which were replaced by permanent tusks a year later. Tusk growth continued throughout life but became slower as the animal reached adulthood. The tusks grew by 2.5–15 cm (0.98–5.91 in) each year.
Columbian mammoths had four functional molar teeth at a time, two in the upper jaw and two in the lower. About 23 cm (9.1 in) of the crown was within the jaw, and 2.5 cm (1 in) was above. The crown was continually pushed forwards and up as it wore down, comparable to a conveyor belt. The teeth had separated ridges of enamel, which were themselves covered in "prisms" that were directed towards the chewing surface. These were quite wear resistant and kept together by cementum and dentine. A mammoth had six sets of molars throughout a lifetime, which were replaced five times. The first molars were about the size of those of a human, 1.3 cm (0.51 in), the third were 15 cm (6 in) 15 cm (5.9 in) long, and the sixth were about 30 cm (1 ft) long and weighed 1.8 kg (4 lb). The molars grew larger and contained more ridges with each replacement. The amount of ridges exceeded 20, and varied across individuals. It took about 10.6 years to grow 180.9 mm of ridge.
As in modern elephants, the sensitive and muscular trunk worked as a limb-like organ with many functions. It was used for manipulating objects, and in social interactions. Adult mammoths could effectively defend themselves from predators with their tusks, trunks and size, but juveniles and weakened adults were vulnerable to pack hunters such as wolves and large felines. Bones of juvenile Columbian mammoths were accumulated by Homotherium, the scimitar-toothed-cat, in Friesenhahn Cave, Texas, but no animals could have hunted healthy adult mammoths. The tusks may also have been used in intra-species fighting, such as territorial fights or fights over mates. Display of the large tusks of males could also have been used to attract females, and to intimidate rivals. Because of their curvature, the tusks were not suitable for stabbing, but may have been used for hitting. Two Columbian mammoths that died with their tusks interlocked found in Nebraska provide evidence of fighting behaviour. The mammoths used their tusks as weapons by thrusting them, swiping them, or crashing them down. They also used the tusks in pushing contests by interlocking them, which sometimes resulted in breakage.
Like modern elephants, Columbian mammoths were likely very social and lived in matriarchal family groups. It is therefore probable that most of their other social behaviour was similar to those of modern elephants. This is supported by fossil assemblages, such as in the Dent Site in Colorado and the Waco Mammoth Site in Waco, Texas, where groups consisting entirely of female and juvenile Columbian mammoths have been found, implying female-led family groups. It has been suggested that the latter group was killed by floodwater, and the arrangement of some of the skeletons may imply that females had formed a defensive ring around juveniles. The opposite situation is represented in the Hot Springs Mammoth Site in South Dakota, where all but one of the many skeletons are male, accumulated over time rather than in a single event. The site represents a 26,000 year old sinkhole (a natural trap), and it is assumed that like modern male elephants, male mammoths mainly lived alone and were more "adventurous", therefore more likely to end up in dangerous situations than the more cautious females.
It is unknown how many mammoths lived at one location at a time, as fossil deposits are often accumulations of individuals that died over long periods of time. It is likely that the amounts varied by season and life-cycle events. Modern elephants form large herds, sometimes formed by multiple family groups, sometimes including thousands of animals migrating together. Mammoths may have formed herds more often, as animals that live in open areas are more likely to form herds than those in forested areas. Accumulations of modern elephant remains have been termed "elephants' graveyards", as these sites were erroneously thought to be where old elephants went to die. Similar accumulations of mammoth bones have been found; it is thought these are the result of individuals dying near or in the rivers over thousands of years, and their bones eventually being brought together by the streams, or due to animals being mired in mud. Some accumulations are also thought to be the remains of herds that died together at the same time, perhaps due to flooding.
The age of a mammoth can be determined by counting the growth rings of its tusks when viewed in cross section. Each major line represents a year, and weekly and daily ones can be found in between. Dark bands correspond to summers, and it is therefore possible to determine the season in which a mammoth died. The growth of the tusks slowed when it became harder to forage, for example during disease, or when a male was banished from the herd. Mammoths continued growing past adulthood, like other elephants. Unfused limb bones show that males grew until they reached the age of 40, and females grew until they were 25. At the age of 6–12 months, the second set of molars would be in the process of erupting, and the first set would be worn out at 18 months of age. The third set of molars lasted for ten years, and this process was repeated until the final, sixth set emerged when the animal was 30 years old. Due to its larger size, the Columbian mammoth probably reached higher ages than woolly mammoths, which could reach about 60 years of age. By then the last set of molars would be worn out, the animal would be unable to chew and feed, and it would die of starvation.
An adult Columbian mammoth would have needed more than 180 kg (400 lb) of food, and may have foraged as long as twenty hours every day. Mammoths chewed their food by using their powerful jaw muscles to move the mandible forwards and close the mouth, then backwards while opening, which made the sharp enamel ridges cut across each other and grind the food. The ridges were wear-resistant to enable the animal to chew large quantities of food, which often contained grit. The trunk could be used for pulling off large grass tufts, picking buds and flowers, and tearing off leaves and branches where trees and shrubs were present. The tusks were also used for obtaining food, such as digging up plants and stripping off bark. This is indicated on many preserved tusks by flat, polished sections up to 30 centimetres (12 in) long on the part of the surface that would have reached the ground.
Stomach contents from Columbian mammoths are rare, since no carcasses are known, but plant remains were found between the pelvis and ribs of the "Huntingdon mammoth" when it was excavated in Utah. These masticated remains were shown to consist of sedge, grass, fir twigs and needles, oak, and maple, through microscopic analysis. A large amount of Columbian mammoth dung has also been found in two caves in Utah. The dry conditions and stable temperature of the Bechan Cave ("Bechan" is Navajo for large faeces) has preserved 16.000-13.500 thousand year old elephant dung most likely belonging to Columbian mammoths. The dung consists of 95% grass and sedge, with 0-25% woody plants between boluses, including saltbush, sagebrush, water birch, and blue spruce. This is similar to the diet documented for the wolly mammoth, though browsing seems to have been more important for the Columbian mammoth in comparison. The cover of dung is 41 cm (16 in) thick, and has a volume of 227 m³ (8.000 cubic ft), with the largest boluses being 20 cm (8 in) in diameter. The Bechan dung could have been produced by a small group of mammoths over a relatively short time, since adult African elephants drop 11 kg (25 lb) of dung on average every second hour, and 90–135 kg (200-300 lb) each day.
It is also theorized that the Columbian Mammoth ate the giant fruits of North America, such as the Osage-orange, Kentucky coffee and Honey locust, as there was no other large herbivore in North America at that time that could ingest these fruits.
Distribution and habitat
The Columbian mammoth inhabited the southern half of North America, which may have had more varied habitats than those areas inhabited by woolly mammoths. Some areas were covered by grass, herbaceous plants, trees and shrub; the exact composition varied from region to region, including grassland, savanna-like, and parkland habitats. There were also various woodlands, and though mammoths would not have preferred forests, clearings within them could provide grass and herbs.
Relationship with humans
In 2011, two 11,000-13,000 year old petroglyphs thought to depict Columbian mammoths were reported at the San Juan River in Utah. Petroglyphs in the Colorado plateau may depict Columbian mammoths, if they are not mastodons instead.
The Columbian mammoth was one of the last members of the American megafauna to go extinct, with the date of disappearance generally set at approximately 12,500 years ago. However, several specimens have been dated to 9,000 years ago or less, and one near Nashville, Tennessee was dated to only about 7,800 years ago. However, dates younger than 11,000 BP have not been viewed as credible.
The remains of Columbian mammoths were discovered in the La Brea Tar Pits, located in Los Angeles, California, and the skeleton of one of them is on exhibit in that site's museum. The Waco Mammoth Site in Waco, Texas, has, so far, produced a collection of bones from 19 females and juveniles who are believed to have died in the same flood event, as well as the skeletons of other mammoths who died in separate flood events.
In 1998, the Washington State Legislature approved the Columbian mammoth as the state fossil. Additionally, a specimen found in Nebraska in 1922 and named "Archie" is the state's official fossil. "Archie" is currently on display at Elephant Hall in Lincoln, Nebraska, and is the largest mounted mammoth specimen in the United States.
The most recent excavation of a Columbian mammoth's remains, which were at a site south of Mexico City, was in March 2013. As these remains had been blanketed in thick volcanic ash about 1 meter (3.3 feet) thick, ground-penetrating radar) was used to locate the fossil. According to local researchers, the mammoth died circa 10,000 BCE–8,000 BCE, at the age of approximately 30 and was the most complete skeleton ever to be found in the country (approximately 70% total by mid-April). As early as 2012, residents of the nearby town of Santa Ana Tlacotenco uncovered the animal's teeth, which were partially concealed by cacti.
- Patterson, D. B.; Mead, A. J.; Bahn, R. A. (2012). "New skeletal remains of Mammuthus columbi from Glynn County, Georgia with notes on their historical and paleoecological significance". Southeastern Naturalist 11 (2): 163–172. doi:10.1656/058.011.0201.
- Osborn, H. F. (1936). Percy, M. R., ed. Proboscidea: A monograph of the discovery, evolution, migration and extinction of the mastodonts and elephants of the world 2. New York: J. Pierpont Morgan Fund.
- Agenbroad, L. D. (2005). "North American Proboscideans: Mammoths: The state of Knowledge, 2003". Quaternary International. 126-128: 73–25. Bibcode:2005QuInt.126...73A. doi:10.1016/j.quaint.2004.04.016.
- McDaniel, G. E.; Jefferson, G. T. (2006). "Mammoths in our midst: The proboscideans of Anza-Borrego Desert State Park®, Southern California, USA". Quaternary International. 142-143: 124. Bibcode:2006QuInt.142..124M. doi:10.1016/j.quaint.2005.03.011.
- Lister, 2007. pp. 18-21
- Shoshani, J.; Tassy, P. (2005). "Advances in proboscidean taxonomy & classification, anatomy & physiology, and ecology & behavior". Quaternary International. 126–128: 5. Bibcode:2005QuInt.126....5S. doi:10.1016/j.quaint.2004.04.011.
- Lister, A. M.; Sher, A. V.; Van Essen, H.; Wei, G. (2005). "The pattern and process of mammoth evolution in Eurasia". Quaternary International. 126–128: 49. Bibcode:2005QuInt.126...49L. doi:10.1016/j.quaint.2004.04.014.
- Ferretti, M. P. (2003). "Structure and evolution of mammoth molar enamel". Acta Palaeontologica Polonica. 3 48: 383–396.
- Lister, 2007. pp. 12–43
- Enk, J.; Devault, A.; Debruyne, R.; King, C. E.; Treangen, T.; O'Rourke, D.; Salzberg, S. L.; Fisher, D.; MacPhee, R.; Poinar, H. (2011). "Complete Columbian mammoth mitogenome suggests interbreeding with woolly mammoths". Genome Biology 12 (5): R51. doi:10.1186/gb-2011-12-5-r51. PMC 3219973. PMID 21627792.
- Gold, D. A.; Robinson, J.; Farrell, A. B.; Harris, J. M.; Thalmann, O.; Jacobs, D. K. (2014). "Attempted DNA extraction from a Rancho La Brea Columbian mammoth (Mammuthus columbi): Prospects for ancient DNA from asphalt deposits". Ecology and Evolution 4 (4): 329–336. doi:10.1002/ece3.928.
- Lister, 2007. pp. 77–95
- McDaniel, G. E.; Jefferson, G. T. (2006). "Dental variation in the molars of Mammuthus columbi var. M. Imperator (Proboscidea, Elephantidae) from a Mathis gravel quarry, southern Texas". Quaternary International. 142-143: 166–177. doi:10.1016/j.quaint.2005.03.014.
- Dirks, W.; Bromage, T. G.; Agenbroad, L. D. (2012). "The duration and rate of molar plate formation in Palaeoloxodon cypriotes and Mammuthus columbi from dental histology". Quaternary International 255: 79. doi:10.1016/j.quaint.2011.11.002.
- Lister, 2007. pp. 96–111
- Malotki, Ekkehart and Wallace, Henry D. Columbian mammoth petroglyphs from the San Juan River near Bluff, Utah, United States [online]. Rock Art Research: The Journal of the Australian Rock Art Research Association (AURA), Vol. 28, No. 2, Nov 2011
- Lister, Adrian; Bahn, Paul (2007). Mammoths - Giants of the Ice Age (3 ed.). London: Frances Lincoln Limited. p. 192.
- BBC - Science & Nature - Wildfacts - Columbian mammoth
- Fiedel, S. (2009). "Sudden Deaths: The Chronology of Terminal Pleistocene Megafaunal Extinction". American Megafaunal Extinctions at the End of the Pleistocene. Vertebrate Paleobiology and Paleoanthropology. pp. 21–37. doi:10.1007/978-1-4020-8793-6_2. ISBN 978-1-4020-8792-9.
- "Waco Mammoth Site - Waco, Texas". Retrieved 16 October 2013.
- "Washington State Fossil". State Symbols USA. Retrieved 16 October 2013.
- "Nebraska State Fossil". State Symbols USA. Retrieved 16 October 2013.
- Boyd, Mildred. "The Regional Museum of Guadalajara". Retrieved 4 December 2012.
- "Mammoth remains discovered in Mexico". Light Years. Cable News Network. April 16, 2013. Retrieved 16 October 2013.
- Lister, A.; Bahn, P. (2007). Mammoths - Giants of the Ice Age (3 ed.). London: Frances Lincoln. ISBN 978-0-520-26160-0.
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