Meridiungulata

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Meridiungulata
Macrauchenia.jpg
Restoration of Macrauchenia patachonica by Robert Bruce Horsfall
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Eutheria
(unranked) Ungulata
(unranked) Mesaxonia
Superorder: Meridiungulata
McKenna 1975
Orders

Meridiungulata is an extinct clade with the rank of cohort or superorder, containing the South American ungulates Pyrotheria (possibly including Xenungulata), Astrapotheria, Notoungulata and Litopterna. It is not known if it is a natural group; it was erected to distinguish the ungulates of South America from other ungulates. Relationships between the orders inside Meridiungulata remain unresolved and it could well be a 'wastebasket' taxon. Most Meridiungulata died out following the invasion of South America by North American ungulates and predators during the Great American Interchange[citation needed]; a few of the largest species of notoungulates and litopterns survived until the end-Pleistocene extinctions.

Taxonomy[edit]

Meridiungulata might have originated in South America from a North American condylarth ancestor,[1] and they may be members of the clade Laurasiatheria, related to other ungulates, including artiodactyls and perissodactyls.[2] It has, however, been suggested the Meridiungulata are part of a different macro-group of placental mammals called Atlantogenata.[3]

Much of the evolution of meridiungulates occurred in isolation from other ungulates, a great example of convergent evolution. However, the argument that meridiungulates are related to artiodactyls and perissodactyls needs support from molecular sequencing. Some paleontologists have also challenged the monophyly of Meridiungulata by suggesting that the pyrotheres are more closely related to other mammals, such as Embrithopoda (an African order possibly be related to elephants), than to other South American ungulates.[4]

Results from the sequencing of collagen from Pleistocene fossils of the notoungulate Toxodon and the litoptern Macrauchenia have indicated that at least these two orders are indeed laurasiatheres, and so form a sister group to odd-toed ungulates.[5][6] This result has been corroborated with mitochondrial DNA extracted from Macrauchenia, which points towards a branching date of 66 million years ago.[7] Panperissodactyla has been proposed as the name of an unranked clade to include perissodactyls and their extinct South American ungulate relatives.[5]

Classification[edit]

The following classification is from Rose 2006:

  • Meridiungulata

Notes[edit]

References[edit]

  • Buckley, M. (2015-04-01). "Ancient collagen reveals evolutionary history of the endemic South American 'ungulates'". Proceedings of the Royal Society B: Biological Sciences. 282 (1806): 20142671–20142671. doi:10.1098/rspb.2014.2671. 
  • Hunter, J.P.; Janis, C.M. (2006). "Spiny Norman in the Garden of Eden? Dispersal and early biogeography of Placentalia". Journal of Mammalian Evolution. 13 (2): 89–123. OCLC 4669969299. doi:10.1007/s10914-006-9006-6. 
  • McKenna, M.C. (1975). "Toward a phylogenetic classification of the Mammalia". In Luckett, W.P.; Szalay, F.S. Phylogeny of the primates: a multidisciplinary approach (Proceedings of WennerGren Symposium no. 61, Burg Wartenstein, Austria, July 6–14, 1974. New York: Plenum. pp. 21–46. ISBN 978-1-4684-2168-2. doi:10.1007/978-1-4684-2166-8_2. 
  • Muizon, C. de; Cifelli, R.L. (2000). "The "condylarths" (archaic Ungulata, Mammalia) from the early Paleocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates". Geodiversitas. 22 (1): 47–150. Retrieved 30 June 2017. 
  • Naish, Darren (2008-02-08). "Snorki the giant’s friends and relatives". Tetrapod Zoology. Archived from the original on 21 May 2013. Retrieved 2014-10-07. 
  • Rose, Kenneth David (2006). The beginning of the age of mammals. Baltimore: JHU Press. ISBN 0801884721. 
  • Shockey, B.J.; Anaya, F. (2004). "Pyrotherium macfaddeni, sp. nov. (late Oligocene, Bolivia) and the pedal morphology of pyrotheres". Journal of Vertebrate Paleontology. 24 (2): 481–488. doi:10.1671/2521. 
  • Welker, F.; Collins, M. J.; Thomas, J. A.; Wadsley, M.; Brace, S.; Cappellini, E.; Turvey, S. T.; Reguero, M.; Gelfo, J. N.; Kramarz, A.; Burger, J.; Thomas-Oates, J.; Ashford, D. A.; Ashton, P. D.; Rowsell, K.; Porter, D. M.; Kessler, B.; Fischer, R.; Baessmann, C.; Kaspar, S.; Olsen, J. V.; Kiley, P.; Elliott, J. A.; Kelstrup, C. D.; Mullin, V.; Hofreiter, M.; Willerslev, E.; Hublin, J.-J.; Orlando, L.; Barnes, I.; MacPhee, R. D. E. (2015-03-18). "Ancient proteins resolve the evolutionary history of Darwin’s South American ungulates". Nature. 522: 81–84. ISSN 0028-0836. PMID 25799987. doi:10.1038/nature14249. 
  • Westbury, M.; Baleka, S.; Barlow, A.; Hartmann, S.; Paijmans, J. L. A.; Kramarz, A.; Forasiepi, A. M.; Bond, M.; Gelfo, J. N.; Reguero, M. A.; López-Mendoza, P.; Taglioretti, M.; Scaglia, F.; Rinderknecht, A.; Jones, W.; Mena, F.; Billet, G.; de Muizon, C.; Aguilar, J. L.; MacPhee, R. D. E.; Hofreiter, M. (2017-06-27). "A mitogenomic timetree for Darwin’s enigmatic South American mammal Macrauchenia patachonica". Nature Communications. 8: 15951. doi:10.1038/ncomms15951.