''Dolichostylodon'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

, belonging to the order

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

. It lived during the Middle

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

, and its fossilized remains were discovered in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

Description

About the size of a

marmot Marmots are large ground squirrels in the genus ''Marmota'', with 15 species living in Asia, Europe, and North America. These herbivores are active during the summer, when they can often be found in groups, but are not seen during the winter, w ...

, this animal was quite similar to other basal notoungulates such as '' Oldfieldthomasia'', '' Ultrapithecus'' and ''

Colbertia ''Colbertia'' is an extinct genus of oldfieldthomasiid notoungulate. It lived from the Early to the Middle Eocene, and its fossilized remains were discovered in Argentina and Brazil. Description This animal was roughly the size of a Virginia ...

'', from which it was mainly distinguished by the characteristics of its teeth. The deciduous premolars were more triangular-shaped than in ''Ultrapithecus'', the paracone was more prominent, and the deciduous third lower premolar had a well-developed metaloph. The upper molars had a very prominent parastyle and metastyle. The metacone column was wider than in ''Colbertia'', and the mesiolabial dimple was not present, while the distolabial dimple was wide and shallow.

Classification

''Dolichostylodon saltensis'' was first described in 2009, based on fossil remains found in the locality El Simbola, in the

Salta Province Salta () is a province of Argentina, located in the northwest of the country. Neighboring provinces are from the east clockwise Formosa, Chaco, Santiago del Estero, Tucumán and Catamarca. It also surrounds Jujuy. To the north it borders Boliv ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. It was a typical basal representative of the order Notoungulata, a large group of mammals that occupied during most of the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

various ecological niches in

. ''Dolichostylodon'' was a member of the family

Oldfieldthomasiidae Oldfieldthomasiidae is an extinct family of notoungulate mammals known from the Late Paleocene to Late Eocene of South America. The family was classified by George Gaylord Simpson in 1945 and a synonym is Acoelodidae, defined by Florentino Ameghi ...

, a possibly paraphyletic group comprising various small and basal notoungulates. Within Oldfieldthomasiidae, ''Dolichostylodon'' was closely related to the other

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...

n species, despite the low-crowned (brachydont) teeth.

Bibliography

*D. A. García López and J. E. Powell. 2009. Un nuevo Oldfieldthomasiidae (Mammalia: Notoungulata) del Paleógeno de la provincia de Salta, Argentina. Ameghiniana 46(1):153-164 Eocene mammals of South America Paleogene Argentina Fossils of Argentina Fossil taxa described in 2009 Prehistoric placental genera Typotheres {{Mammal-stub