''Monotrematum sudamericanum'' is an extinct

monotreme Monotremes () are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

from the Paleocene ( Peligran)

Salamanca Formation The Salamanca Formation is a geologic formation in the Golfo San Jorge Basin of central Patagonia that yields well-preserved, well-dated fossils from the early Paleocene. Studies of these fossils are providing new data on plant and animal diversit ...

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. It is one of only two monotremes found outside

Oceania Oceania ( , ) is a region, geographical region including Australasia, Melanesia, Micronesia, and Polynesia. Outside of the English-speaking world, Oceania is generally considered a continent, while Mainland Australia is regarded as its co ...

Taxonomy

A species described in 1992 and assigned to a new genus ''Monotrematum'' as the type. It is currently the only known species of the genus. The authors compared their fossil material to the genus '' Obdurodon'',

ornithorhynchid The Ornithorhynchidae are one of the two extant families in the order Monotreme, Monotremata, and contain the platypus and its extinct relatives. The other family is the Tachyglossidae, or echidnas. Within the Ornithorhynchidae are the main Cen ...

species first discovered at Australian fossil sites in 1975. It is considered to possibly be a

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

-ornithorhynchid, although this is uncertain given that several divergence estimates have found the family to be significantly younger.

Description

''Monotrematum sudamericanum'' is known only from two lower and one upper

platypus The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or monotypi ...

-like teeth. It is the only known non-

Australasia Australasia is a subregion of Oceania, comprising Australia, New Zealand (overlapping with Polynesia), and sometimes including New Guinea and surrounding islands (overlapping with Melanesia). The term is used in a number of different context ...

. The main difference, apart from continent and age, is its size: the teeth of ''Monotrematum'' are around twice as large as those of other similar species in the related genus '' Obdurodon''. The teeth of ''M. sudamericanum'' presently reside in the collections of Museo de La Plata and Museo Paleontológico Egidio Feruglio, both in Argentina. According to Pascual, "The preserved enamel in the central region shows that the crown pattern is almost identical to that of ''Obdurodon'': it is composed of two V-shaped lobes, the anterior of which is wider, separated from the posterior one by a valley that connects the lingual and buccal sides of the crown separating the anterior and posterior lobes."

References

External links

* {{Taxonbar, from=Q782618 Ornithorhynchidae Prehistoric monotremes Paleocene mammals of South America Peligran Paleogene Argentina Fossils of Argentina Fossil taxa described in 1992 Taxa named by Rosendo Pascual Taxa named by Mike Archer (paleontologist) Taxa named by Edgardo Ortiz Jaureguizar Taxa named by Joyce Rodrigues do Prado Taxa named by Henk Godthelp Taxa named by Suzanne J. Hand Prehistoric mammal genera Golfo San Jorge Basin Salamanca Formation