Xenungulata

Xenungulata Temporal range: Late Paleocene-Early Eocene (Riochican-Casamayoran) ~58.6–48.7  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Interpretation of Carodnia vieirai
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Placentalia
Clade:	† Meridiungulata
Order:	† Xenungulata Paula Couto 1952
Family and genera [1]
†Carodniidae Paula Couto 1952 [2] † Carodnia Simpson 1935 † Etayoa Villarroel 1987 † Rodcania Gelfo, García-López & Bergqvist 2020 [3] † Notoetayoa Gelfo, López & Bond 2008

Xenungulata ("strange ungulates") is an order of extinct and primitive South American hoofed mammals that lived from the Late Paleocene to Early Eocene (Itaboraian to Casamayoran in the SALMA classification). Fossils of the order are known from deposits in Brazil, Argentina, Peru, ^[4] and Colombia. The best known member of this enigmatic order is the genus Carodnia , a tapir-like and -sized animal with a gait similar to living African elephants. ^[5]

Description

Xenungulates are characterized by bilophodont M^1–2 and M_1–2, similar to pyrotheres, and complex lophate third molars, similar to uintatheres. Though other relationships, to arctocyonids for example, have been suggested, no proofs thereof have been found. The foot bones of xenungulates were short and robust and their digits terminated in broad, flat, and unfissured hoof-like unguals, quite unlike any other meridiungulates. The discovery of Etayoa in Colombia ^[6] made it clear that xenungulates are distinct from other groups: Etayoa lacks lophate molar talonid (in contrast to Carodnia) and, since no distinct lophodonty is present in basal pyrotheres, there is reason to assume that bilophodonty evolved separately in xenungulates and pyrotheres. Xenungulates also show some dental similarity to primitive astrapotheres. ^[7]

Taxonomy

Cifelli 1983 grouped Carodnia with pyrotheres based on a similarity in astragalus morphology, but later concluded that this observation was incorrect. ^[8]

Notoetayoa is most closely related to Etayoa. ^[9]

Distribution

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Locations of Xenungulata fossils
Bogotá Formation
Peñas Coloradas Formation
Mogollón Formation
Itaboraí Formation

Xenungulata fossils have been found in: ^[10]

• Bogotá Formation, Casamayoran, Colombia
• Peñas Coloradas Formation, Riochican, Argentina
• Mogollón Formation, Itaboraian-Riochican, Peru
• Itaboraí Formation, Itaboraian, Brazil

References

1. "Xenungulata". Palaeocritti. Retrieved 4 May 2013.
2. Carodniidae in the Paleobiology Database. Retrieved May 2013.
3. Gelfo, Javier N.; García-López, Daniel A.; Bergqvist, Lilian P. (2020). "Phylogenetic relationships and palaeobiology of a new xenungulate (Mammalia: Eutheria) from the Palaeogene of Argentina". Journal of Systematic Palaeontology. 18 (12): 993–1007. doi:10.1080/14772019.2020.1715496. S2CID   213052956.
4. Antoine et al. 2015
5. Fariña, Vizcaíno & De Iuliis 2013 , p. 86
6. Villarroel 1987
7. Rose 2006 , Xenungulata, p. 238
8. Gingerich 1985 , p. 131
9. Gelfo, López & Bond 2008 , Abstract
10. Xenungulata at Fossilworks.org

Bibliography

• Antoine, Pierre-Olivier; Billet, Guillaume; Salas Gismondi, Rodolfo; Tejada Lara, Julia; Baby, Patrice; Brusset, Stéphane; Espurt, Nicolas (2015). "A New Carodnia Simpson, 1935 (Mammalia, Xenungulata) from the Early Eocene of Northwestern Peru and a Phylogeny of Xenungulates at Species Level". Journal of Mammalian Evolution . 22 (2): 129–140. Retrieved 2019-02-13.
• Cifelli, Richard (1983). "Eutherian tarsals from the late Paleocene of Brazil". American Museum Novitates (2761). hdl:2246/5252. OCLC   10601277. Cifelli 1983
• Fariña, Richard A.; Vizcaíno, Sergio F.; De Iuliis, Gerry (2013). Megafauna: Giant Beasts of Pleistocene South America. Indiana University Press. ISBN   9780253007193. OCLC   779244424 . Retrieved 4 May 2013. Fariña, Vizcaíno & De Iuliis 2013
• Gelfo, Javier N.; López, Guillermo M.; Bond, Mariano (2008). "A new Xenungulata (Mammalia) from the Paleocene of Patagonia Argentina". Journal of Paleontology. 82 (2): 329–35. doi:10.1666/06-099.1. OCLC   4631927277. S2CID   131263926. Gelfo, López & Bond 2008
• Gingerich, Philip D. (1985). "South American Mammals in the Paleocene of North America" (PDF). In Stehli, Francis G.; Webb, S. David (eds.). The Great American Biotic Interchange. Topics in Geobiology. Vol. 4. Springer. pp. 123–137. doi:10.1007/978-1-4684-9181-4_5. ISBN   978-1-4684-9183-8. OCLC   716806225 . Retrieved 4 May 2013. Gingerich 1985
• Rose, Kenneth David (2006). The beginning of the age of mammals. Baltimore: JHU Press. ISBN   978-0801884726. Rose 2006
• Paula Couto, Carlos, de (1952). "Fossil mammals from the beginning of the Cenozoic in Brazil. Condylarthra, Litopterna, Xenungulata, and Astrapotheria". Bulletin of the American Museum of Natural History. 99: 355–394. hdl:2246/417. OCLC   18189741. Paula Couto 1952
• Simpson, George Gaylord (1935). "Descriptions of the oldest known South American mammals, from the Río Chico Formation". American Museum Novitates. Publications of the Scarritt Expeditions, no. 24 (793). hdl:2246/2125. OCLC   44083494. Simpson 1935
• Villarroel, Carlos (1987). "Características y afinidades de Etayoa n. gen., tipo de una nueva familia de Xenungulata (Mammalia) del Paleoceno medio (¿) de Colombia". Comunicaciones Paleontologicas del Museo de Historia Natural del Montevideo. 1 (19): 241–253. OCLC   18731966. Villarroel 1987