Columbian mammoth

From Wikipedia, the free encyclopedia
  (Redirected from Columbian Mammoth)
Jump to: navigation, search
Columbian mammoth
Temporal range: Late Pleistocene to Early Holocene, 0.013–0.011Ma
Columbian mammoth.JPG
Columbian mammoth in the Page Museum at the La Brea Tar Pits, Los Angeles
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Proboscidea
Family: Elephantidae
Genus: Mammuthus
Species: M. columbi
Binomial name
Mammuthus columbi
(Falconer, 1857)
Synonyms

The Columbian mammoth (Mammuthus columbi) was a species of mammoth of the Quaternary period that appeared in North America (in the present United States and to as far south as Nicaragua and Honduras) during the late Pleistocene.

Taxonomy[edit]

Specimen formerly referred to M. imperator

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.[1] This has also been accepted by other scientists.[2]

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.[3] 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.[4]

Evolution[edit]

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 separate mammutidae family, which diverged 25 million years before the mammoths evolved.[5] The following cladogram shows the placement of the Columbian mammoth among other proboscideans, based on hyoid characteristics:[6]




Mammut americanum (American mastodon)




Gomphotherium sp.




Stegodon zdanskyi




Loxodonta africana (African elephant)




Elephas maximus (Asian elephant)



Mammuthus columbi (Columbian mammoth)








M. jeffersonii, a possible hybrid between Columbian and woolly mammoths

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 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.[7] These adaptations were acquired gradually as mammoths turned to more abrasive food items.[8]

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.[7] The Columbian mammoth, M. columbi, evolved from a population of M. trogontherii that had entered North America. 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.[9]

Description[edit]

Restoration by Robert Bruce Horsfall, 1912

The Columbian mammoth was a savanna and grassland inhabitant, similar to the modern African elephant. Large males ranged from 3.7–4.0 m (12.1–13.1 ft) and weighed between 7–9 metric tons (7.7–9.9 short tons) with spiralled tusks that could grow up to 4.25 metres (13.9 ft) long.[10]

It was a herbivore, with a diet consisting of varied plant life ranging from grasses to conifers. 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. Using studies of African elephants, it has been estimated that a large male would have eaten approximately 700 pounds (320 kg) of plant material daily.[citation needed] The average Columbian mammoth ate 300 pounds of vegetation a day.

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.[11]

Discovery[edit]

Excavation of specimens at the Waco Mammoth Site

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.[12] This mammoth also lived in Mexico, where its remains are very common. A large individual is the central exhibit in the Regional Museum of Guadalajara, in the Mexican state of Jalisco.[13]

In 1998, the Washington State Legislature approved the Columbian mammoth as the state fossil.[14] 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.[15]

In 2011, two 11,000-13,000 year old petroglyphs thought to depict Columbian mammoths were reported at the San Juan River in Utah.[16] Petroglyphs in the Colorado plateau may depict Columbian mammoths, if they are not mastodons instead.[11]

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.[17]

References[edit]

  1. ^ 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.  edit
  2. ^ 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.  edit
  3. ^ BBC - Science & Nature - Wildfacts - Columbian mammoth
  4. ^ Fiedal, Stuart (2009). "Sudden Deaths: The Chronology of Terminal Pleistocene Megafaunal Extinction". In Haynes, Gary. American Megafaunal Extinctions at the End of the Pleistocene. Springer. pp. 21–37. doi:10.1007/978-1-4020-8793-6_2. ISBN 978-1-4020-8792-9. 
  5. ^ Lister, 2007. pp. 18-21
  6. ^ 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.  edit
  7. ^ a b 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.  edit
  8. ^ Ferretti, M. P. (2003). "Structure and evolution of mammoth molar enamel". Acta Palaeontologica Polonica. 3 48: 383–396. 
  9. ^ 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.  edit
  10. ^ "Quick facts". Denver Museum of Nature & Science. Retrieved 27 June 2012. 
  11. ^ a b Lister, Adrian; Bahn, Paul (2007). Mammoths - Giants of the Ice Age (3 ed.). London: Frances Lincoln Limited. p. 192. 
  12. ^ "Waco Mammoth Site - Waco, Texas". Retrieved 16 October 2013. 
  13. ^ Boyd, Mildred. "The Regional Museum of Guadalajara". Retrieved 4 December 2012. 
  14. ^ "Washington State Fossil". State Symbols USA. Retrieved 16 October 2013. 
  15. ^ "Nebraska State Fossil". State Symbols USA. Retrieved 16 October 2013. 
  16. ^ 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
  17. ^ "Mammoth remains discovered in Mexico". Light Years. Cable News Network. April 16, 2013. Retrieved 16 October 2013. 

External links[edit]