''Austrotriconodon'' is a

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 ...

genus 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 ...

and

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 ...

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 ...

. It currently contains only the type species, ''A. mckennai''. Originally assumed to be a

eutriconodont Eutriconodonta is an order (biology), order of early mammals. Eutriconodonts existed in Asia (including Insular India, pre-contact India), Africa, Europe, North America, North and South America during the Jurassic and the Cretaceous periods. The ...

, more recent studies have recovered it as a

meridiolestida Meridiolestida is an extinct clade of mammals known from the Cretaceous and Cenozoic of South America and possibly Antarctica. They represented the dominant group of mammals in South America during the Late Cretaceous. Meridiolestidans were morph ...

dryolestoid Dryolestida is an extinct order of mammals, known from the Jurassic and Cretaceous. They are considered Basal (phylogenetics), basal members of the clade Cladotheria, close to the ancestry of therian mammals. It is also believed that they develop ...

Description

''Austrotriconodon'' is known only from its teeth. Their similarity to the triconodont teeth of mammals such as

eutriconodonts Eutriconodonta is an order of early mammals. Eutriconodonts existed in Asia (including pre-contact India), Africa, Europe, North and South America during the Jurassic and the Cretaceous periods. The order was named by Kermack ''et al.'' in 1973 ...

has caused taxonomic confusion and referral of this taxon to eutriconodonta; however, discovery of similar teeth in animals such as '' Cronopio'' has led to its reinterpretation as a meridolestidan.

Discovery and species

''Austrotriconodon'' fossils were found in the Argentinean

Los Alamitos Formation The Los Alamitos Formation is a geological Formation (geology), formation of the North Patagonian Massif in Rio Negro Province, northwestern Patagonia, Argentina, whose strata date back to the Late Cretaceous (Campanian, Late Campanian to Maastri ...

, dating to the

age. The only known fossils are two lower premolariform teeth. The holotype of ''A. mckennai'' was later referred to by Bonaparte as "''A. ferox''" in the caption to an image figuring it. This name has been ignored by later researchers and is considered an objective synonym of ''A. mckennai''. A second species, ''A. sepulvedai'', was named by Bonaparte in 1992. However, a 2013 reinterpretation placed this taxon within Mesungulatidae, separate from ''A. mckennai'', and considered the name "''Austrotriconodon''" ''sepulvadai'' an invalid combination. The authors suggested possible synonymy with '' Mesungulatum houssayi'' but neither synonymised the two nor named a new genus.

References

{{Taxonbar, from=Q5712329 Meridiolestida Monotypic prehistoric mammal genera Campanian life Maastrichtian life Late Cretaceous mammals of South America Cretaceous Argentina Fossils of Argentina Los Alamitos Formation Fossil taxa described in 1986 Taxa named by José Bonaparte