{{Short description|Extinct genus of marsupials}} {{Italic title}} {{speciesbox | fossil_range = Early Danian<br/>(pre-Tiupampan)<br/>~{{fossil range|64}} | genus = Cocatherium | parent_authority = Goin et al. 2006 | species = lefipanum | authority = 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''.<ref name=FWCocatherium>[https://paleobiodb.org/classic/displayCollResults?collection_no=192149 ''Cocatherium''] at Fossilworks.org</ref>
The mammal, probably belonging to the Polydolopimorphia, is the oldest known representative of marsupials or any therian mammal in the Southern Hemisphere.
== Etymology == 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.<ref name=Goin2006_p505>Goin et al., 2006, p.505</ref>
== Description == ''Cocatherium'' was described on the basis of the holotype fossil LIEB-PV 1001, an isolated right lower molar with a total length {{convert|2.90|mm|in}}, a trigonid width of {{convert|2.20|mm|in}} and a talonid width of {{convert|2.27|mm|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.<ref name=Goin2006_p507>Goin et al., 2006, p.507</ref> The presence of the mammal predates the Tiupampan South American land mammal age.<ref name=Woodburne2013_p7>Woodburne et al., 2013, p.7</ref>
== Classification == ''Cocatherium'' probably represents a basal polydolopiform, closely related to ''Roberthoffstetteria''.<ref name=Woodburne2013_p38>Woodburne et al., 2013, p.38</ref> Polydolopoids are dentally derived marsupials primarily from the Paleocene and Eocene of South America. At least two genera are known from Antarctica.<ref name=FossilHunt>[https://www.fossilhunters.xyz/age-of-mammals/h-wnn.html Polydolopimorphia]</ref> 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.<ref name=Goin2006_p508>Goin et al., 2006, p.508</ref>
== Paleoecology ==
{{main|Lefipán Formation#The Cretaceous-Paleogene extinction event}} The Lefipán Formation ranges in age from the late Maastrichtian to the early Danian and preserves the Cretaceous-Paleogene boundary, though the exact layer is disturbed by bioturbation.<ref name=Donovan2016_p4>Donovan et al., 2016, p.4</ref> The Danian section of the formation shows a remarkably rapid recovery from the extinction event,<ref name=Donovan2016_p1>Donovan et al., 2016, p.1</ref> with aquatic plant taxa virtually undisturbed and other flora reappearing quickly.<ref name=Cuneo2014_p14>Cúneo et al., 2014, p.14</ref> A layer in the formation, known as the ''Turitella'' bed, is considered closest to the onset of the Paleogene and the fossil of ''Cocatherium'', as well as the bivalve ''Meretrix chalcedonica'', was found approximately {{convert|5|m|ft}} above the estimated K/Pg boundary.<ref name=Goin2006_p506>Goin et al., 2006, p.506</ref>
The formation has provided several macro- and microfossils of flora, which has led researchers to conclude the rapid recovery and low extinction rate of several genera and families of plants.<ref name=Barreda2012_p6>Barreda et al., 2012, p.6</ref> Hemipteran insect predation on leaves is noted at levels slightly above the K/Pg boundary.<ref name=Wilf2017_p1360>Wilf et al., 2017, p.1360</ref> While ''Cocatherium'' is the only mammal found in the formation, shark,<ref name=Goin2006_p507/> and ray teeth of ''Hypolophodon patagoniensis'',<ref name=Cione2013_p3>Cione et al., 2013, p.3</ref> occur in the Danian section and are indicative of a shallow marine to littoral (coastal) environment.<ref name=Cione2013_p6>Cione et al., 2013, p.6</ref>
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== See also == * ''Chulpasia'', from Early Eocene (Itaboraian) Peru * ''Didelphodon'', from Campanian to Maastrichtian North America * ''Eodelphis'', from Campanian North America
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== References == {{Reflist|20em}}
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Category:Prehistoric marsupial genera Category:Paleocene mammals of South America Category:Paleogene Argentina Category:Fossils of Argentina Category:Cañadón Asfalto Basin Category:Fossil taxa described in 2006 Category:Taxa named by Francisco J. Goin Category:Danian genera