''Elmerriggsia'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

Notoungulate Notoungulata is an extinct order of ungulates that inhabited South America from the early Paleocene to the end of the Pleistocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms re ...

, belonging to the family

Leontiniidae Leontiniidae is an extinct family comprising eighteen genera of notoungulate mammals known from the Middle Eocene (Mustersan) to Late Miocene (Huayquerian) of South America South America is a continent entirely in the Western Hemisphere ...

. It lived during the Late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

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 ...

Description

This animal, like all leontiniids, had a fairly robust body and strong legs. Unlike most of its relatives, however, ''Elmerriggsia'' was less than 1,5 meters long. ''Elmerriggsia'' had the V-shaped skull when viewed from above, the canine-shaped upper incisors (as well as the third lower incisor), and the mesodont typed dentition characteristic of all leontiniids. The skull of ''Elmerriggsia'' was characterized by the presence of premolars with a grooved protocone, without an intermediate lingual cingulum, and by a well developed labial cingulum on the lower molars. These dental features distinguished ''Elmerriggsia'' from any other leontiniids.

Classification

''Elmerriggsia fieldia'' was first described in 2012, based on fossil remains found near

Pico Truncado Pico Truncado is a town and municipality in Santa Cruz Province in southern Argentina. In 1921, the village's railway station was the site of one of the few open engagements between the Argentine Army and anarchist strikers at the time of the e ...

in the Santa Cruz Province of

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 ...

, in terrains dated from the

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 ...

(Late

). The fossils had been discovered over 75 years earlier, during an expedition to Argentina organized in 1924 by the

Field Museum The Field Museum of Natural History (FMNH), also known as The Field Museum, is a natural history museum in Chicago, Illinois, and is one of the largest such museums in the world. The museum is popular for the size and quality of its educationa ...

and led by Elmer S. Riggs, and were informally known as ''Leontinia'' sp.. Various fossils attributed to this animal were not only discovered near Pico Truncado, but also in various other areas of Argentina. ''Elmerriggsia'' was a rather basal leontiniid, despite its Late Oligocene age ; according to a cladistic analysis carried out in 2012, ''Elmerriggsia'' was part of a basal clade of leontiniids, shared with the

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 ...

genera ''

Martinmiguelia ''Martinmiguelia'' is an extinct genus of Notoungulate, belonging to the family Leontiniidae. It lived during the Middle Eocene, and its fossil remains were found in South America. Description This animal is only known from skull and mandible r ...

'' and ''

Coquenia ''Coquenia'' is an extinct genus of Notoungulate, belonging to the family Leontiniidae. It lived during the Middle Eocene, in what is today Argentina. Description Known only from skull and mandible remains, ''Coquenia'' may have been a heavily ...

''.

Bibliography

*B. J. Shockey, J. J. Flynn, D. A. Croft, P. Gans, and A. R. Wyss. 2012. New leontiniid Notoungulata (Mammalia) from Chile and Argentina: comparative anatomy, character analysis, and phylogenetic hypotheses. American Museum Novitates 3737:1-64 Toxodonts Oligocene mammals of South America Paleogene Argentina Fossils of Argentina Fossil taxa described in 2012 Prehistoric placental genera {{notoungulate-stub