Cocatherium
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''Cocatherium'' is an extinct
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...
mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s of uncertain family placement, from the earliest
Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...
( early Danian) of
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
, predating the
Tiupampan The Tiupampan () age is a period of geologic time (64.5–62.5 Ma) within the Paleocene epoch of the Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from th ...
South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as age ...
. The genus was described based on a fossil molar that was found in the
Danian The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretac ...
part of the Cretaceous-Paleogene
Lefipán Formation The Lefipán Formation is a Maastrichtian to Danian, straddling the Cretaceous-Paleogene boundary, geologic Formation (geology), formation of the Cañadón Asfalto Basin in Chubut Province, Patagonia, Argentina. The up to thick stratigraphic unit ...
in the
Cañadón Asfalto Basin The Cañadón Asfalto Basin () is an irregularly shaped sedimentary basin located in north-central Patagonia, Argentina. The basin stretches from and partly covers the North Patagonian Massif in the north, a high forming the boundary of the basin ...
in north-central
Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...
,
Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
. The
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
of the genus is ''C. lefipanum''.''Cocatherium''
at
Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...
.org
The mammal, probably belonging to the
Polydolopimorphia Polydolopimorphia is an extinct order of metatherians, closely related to extant marsupials. Known from the Paleocene-Pliocene of South America and the Eocene of Antarctica, they were a diverse group during the Paleogene, filling many niches, bef ...
, 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 The La Plata Museum () is a natural history museum in La Plata, Argentina. It is part of the (Natural Sciences School) of the National University of La Plata. The building, long, today houses three million fossils and relics (including 44,000 bo ...
in working in the region where the fossils were found. The species
epithet An epithet (, ), also a byname, is a descriptive term (word or phrase) commonly accompanying or occurring in place of the name of a real or fictitious person, place, or thing. It is usually literally descriptive, as in Alfred the Great, Suleima ...
''lefipanum'' honors Lefipán, one of the most prominent native
Mapuche The Mapuche ( , ) also known as Araucanians are a group of Indigenous peoples of the Americas, Indigenous inhabitants of south-central Chile and southwestern Argentina, including parts of Patagonia. The collective term refers to a wide-ranging e ...
inhabitants of the region where the Lefipán Formation was deposited.Goin et al., 2006, p.505


Description

''Cocatherium'' was described on the basis of the
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
fossil LIEB-PV 1001, an isolated right lower molar with a total length , a trigonid width of and a talonid width of . The molar has a well-developed wear pattern, contains all the features characteristic of a therian mammal and indicates it belonged to a
bunodont The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth ...
marsupial of relatively large size. The mammal is the oldest known representative of marsupials or any therian mammal in the Southern Hemisphere.Goin et al., 2006, p.507 The presence of the mammal predates the
Tiupampan The Tiupampan () age is a period of geologic time (64.5–62.5 Ma) within the Paleocene epoch of the Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from th ...
South American land mammal age The South American land mammal ages (SALMA) establish a geologic timescale for prehistoric South American fauna beginning 64.5 Ma during the Paleocene and continuing through to the Late Pleistocene (0.011 Ma). These periods are referred to as age ...
.Woodburne et al., 2013, p.7


Classification

''Cocatherium'' probably represents a basal polydolopiform, closely related to '' Roberthoffstetteria''.Woodburne et al., 2013, p.38 Polydolopoids are dentally derived marsupials primarily from the Paleocene and Eocene of South America. At least two genera are known from Antarctica.Polydolopimorphia
/ref> According to the describing authors, the genus possibly belongs to the ?
Polydolopimorphia Polydolopimorphia is an extinct order of metatherians, closely related to extant marsupials. Known from the Paleocene-Pliocene of South America and the Eocene of Antarctica, they were a diverse group during the Paleogene, filling many niches, bef ...
, together with other North and South American genera as '' Iugomortiferum'' from the
Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...
Wahweap Formation The Wahweap Formation of the Grand Staircase–Escalante National Monument is a geological Formation (geology), formation in southern Utah and northern Arizona, around the Lake Powell region, whose strata date back to the Late Cretaceous (Campan ...
of
Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...
, '' Bonapartherium'' from the
Casamayoran The Casamayoran () age is a period of geologic time (50.0–48.0 Ma) within the Early Eocene epoch of the Paleogene, used more specifically within the South American land mammal age (SALMA) classification. It follows the Itaboraian and precedes th ...
Lumbrera Formation and
Mustersan The Mustersan age is a period of geologic time (48.0–42.0 Mya (unit), Ma) within the Eocene epoch of the Paleogene, used more specifically within the South American land mammal age (SALMA) classification. It follows the Casamayoran and precedes th ...
Geste Formation The Geste Formation () is a fossiliferous geologic formation of the Puna Plateau in the western Salta Province and northern Catamarca Province of the Argentine Northwest, northwestern Argentina. The formation, reaching a thickness of , is the ol ...
of Argentina, '' Epidolops'' of the
Itaboraian The Itaboraian () age is a period within the Early Eocene geologic time (53.0–50.0 Ma) epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Riochican and precedes the Casamayoran age. E ...
Las Flores Formation of the
Golfo San Jorge Basin The Golfo San Jorge Basin () is a hydrocarbon-rich sedimentary basin located in eastern Patagonia, Argentina. The basin covers the entire San Jorge Gulf and an inland area west of it, having one half located in Santa Cruz Province and the other i ...
, '' Polydolops'' from
Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
Argentina,
La Meseta Formation The La Meseta Formation is a sedimentary sequence deposited during much of the Paleogene on Seymour Island off the coast of the Antarctic Peninsula. It is noted for its fossils, which include both marine organisms and the only terrestrial vertebr ...
of
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
and
Deseadan The Deseadan () age is a period of geologic time (29.0–21.0 Ma) within the Oligocene epoch of the Paleogene to the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It follows the Tingu ...
Salla Formation Salla, known as Kuolajärvi until 1936, is a municipality of Finland, located in Lapland. The municipality has a population of () and covers an area of of which is water. The population density is . The nearby settlement of Sallatunturi is ...
of
Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...
, '' Prepidolops'', from the Lumbrera Formation, '' Ectocentrocristus'', from the Maastrichtian
Judith River The Judith River is a tributary of the Missouri River, approximately 124 mi (200 km) long, running through central Montana in the United States. It rises in the Little Belt Mountains and flows northeast past Utica and Hobson. It is ...
and
Kirtland Formation The Kirtland Formation (originally the Kirtland Shale) is a Sedimentary rock, sedimentary geological formation. Description The Kirtland Formation is the product of alluvial muds and overbank sand deposits from the many channels draining the ...
s of the United States, ''Roberthoffstetteria'' of the Tiupampan
Santa Lucía Formation The Santa Lucía Formation is a Maastrichtian to Paleocene (Danian) geologic Formation (geology), formation in Bolivia. Fossil ornithopod tracks have been reported from the Cretaceous lower part of the formation.Weishampel, et al., 2004, pp.517-607 ...
of Bolivia, '' Procaroloameghinia'' of Las Flores Formation, and '' Caroloameghinia'' from the Casamayoran
Sarmiento Formation The Sarmiento Formation (Spanish language, Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million y ...
of Argentina.Goin et al., 2006, p.508


Paleoecology

The Lefipán Formation ranges in age from the late
Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...
to the early
Danian The Danian is the oldest age or lowest stage of the Paleocene Epoch or Series, of the Paleogene Period or System, and of the Cenozoic Era or Erathem. The beginning of the Danian (and the end of the preceding Maastrichtian) is at the Cretac ...
and preserves the Cretaceous-Paleogene boundary, though the exact layer is disturbed by
bioturbation Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a ...
.Donovan et al., 2016, p.4 The Danian section of the formation shows a remarkably rapid recovery from the extinction event,Donovan et al., 2016, p.1 with aquatic plant taxa virtually undisturbed and other flora reappearing quickly.Cúneo et al., 2014, p.14 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 Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
'' Meretrix chalcedonica'', was found approximately above the estimated K/Pg boundary.Goin et al., 2006, p.506 The formation has provided several macro- and microfossils of
flora Flora (: floras or florae) is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. The corresponding term for animals is ''fauna'', and for f ...
, which has led researchers to conclude the rapid recovery and low extinction rate of several genera and families of plants.Barreda et al., 2012, p.6
Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from ...
n insect predation on leaves is noted at levels slightly above the K/Pg boundary.Wilf et al., 2017, p.1360 While ''Cocatherium'' is the only mammal found in the formation, shark, and ray teeth of '' Hypolophodon patagoniensis'',Cione et al., 2013, p.3 occur in the Danian section and are indicative of a shallow marine to littoral (coastal) environment.Cione et al., 2013, p.6


See also

* '' Chulpasia'', from Early Eocene (
Itaboraian The Itaboraian () age is a period within the Early Eocene geologic time (53.0–50.0 Ma) epoch of the Paleogene, used more specifically with South American land mammal ages (SALMA). It follows the Riochican and precedes the Casamayoran age. E ...
) Peru * ''
Didelphodon ''Didelphodon'' (from ''is''/nowiki>">/nowiki>''is''/nowiki> "opossum" tooth "tooth") is a genus of extinct metatherian mammal from the Late Cretaceous of North America. Description Although perhaps little larger than a Virginia opossum, wit ...
'', from Campanian to Maastrichtian North America * ''
Eodelphis ''Eodelphis'', from eo- (dawn) and /nowiki>''delphis''">/nowiki>/nowiki>''delphis'' (a genus of Opossum), thus meaning "dawn opossum", is a genus of stagodont metatherians from the Late Cretaceous of North America, with distinctive crushing de ...
'', from Campanian North America


References


Bibliography

* * * * * * * {{Taxonbar, from=Q21998075 Prehistoric marsupial genera Paleocene mammals of South America Paleogene Argentina Fossils of Argentina Cañadón Asfalto Basin Fossil taxa described in 2006 Taxa named by Francisco J. Goin Danian genera