Cocatherium
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| Cocatherium | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Marsupialia |
| Order: | †?Polydolopimorphia |
| Genus: | †Cocatherium Goin et al. 2006 |
| Species: | †C. lefipanum |
| Binomial name | |
| †Cocatherium lefipanum Goin et al. 2006 | |
Cocatherium is an extinct genus of marsupial mammals of uncertain family placement, from the earliest Paleocene (early Danian) of South America, predating the Tiupampan South American land mammal age. The genus was described based on a fossil molar that was found in the Danian part of the Cretaceous-Paleogene Lefipán Formation in the Cañadón Asfalto Basin in north-central Patagonia, Argentina. The type species of the genus is C. lefipanum.[1]
The mammal, probably belonging to the Polydolopimorphia, is the oldest known representative of marsupials or any therian mammal in the Southern Hemisphere.
The genus was named Cocatherium ("Coca Beast") after "Coca", the nickname of San Martín of Estancia San Ramón, who assisted the researchers of the Museo de La Plata in working in the region where the fossils were found. The species epithet lefipanum honors Lefipán, one of the most prominent native Mapuche inhabitants of the region where the Lefipán Formation was deposited.[2]
Description
Cocatherium was described on the basis of the holotype fossil LIEB-PV 1001, an isolated right lower molar with a total length 2.90 millimetres (0.114 in), a trigonid width of 2.20 millimetres (0.087 in) and a talonid width of 2.27 millimetres (0.089 in). The molar has a well-developed wear pattern, contains all the features characteristic of a therian mammal and indicates it belonged to a bunodont marsupial of relatively large size. The mammal is the oldest known representative of marsupials or any therian mammal in the Southern Hemisphere.[3] The presence of the mammal predates the Tiupampan South American land mammal age.[4]
Classification
Cocatherium probably represents a basal polydolopiform, closely related to Roberthoffstetteria.[5] Polydolopoids are dentally derived marsupials primarily from the Paleocene and Eocene of South America. At least two genera are known from Antarctica.[6] According to the describing authors, the genus possibly belongs to the ?Polydolopimorphia, together with other North and South American genera as Iugomortiferum from the Campanian Wahweap Formation of Utah, Bonapartherium from the Casamayoran Lumbrera Formation and Mustersan Geste Formation of Argentina, Epidolops of the Itaboraian Las Flores Formation of the Golfo San Jorge Basin, Polydolops from Eocene Argentina, La Meseta Formation of Antarctica and Deseadan Salla Formation of Bolivia, Prepidolops, from the Lumbrera Formation, Ectocentrocristus, from the Maastrichtian Judith River and Kirtland Formations of the United States, Roberthoffstetteria of the Tiupampan Santa Lucía Formation of Bolivia, Procaroloameghinia of Las Flores Formation, and Caroloameghinia from the Casamayoran Sarmiento Formation of Argentina.[7]