''Alphadon'' is an extinct genus of small, primitive

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 ...

that was a member of the

metatheria Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as wel ...

ns, a group of mammals that includes modern-day

marsupials 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 ...

. Its fossils were first discovered and named by

George Gaylord Simpson George Gaylord Simpson (June 16, 1902 – October 6, 1984) was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the modern synthesis, contributing '' Tempo ...

in 1929.

Description

Not much is known about the appearance of ''Alphadon'', as it is only known from teeth, a lower jaw and skull fragments. It probably grew to about and may have resembled a modern

opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 126 species in 18 genera. Opossums originated in South America and entered North A ...

. Judging from its teeth, it was likely an

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

, feeding on fruits, invertebrates and possibly small vertebrates. ''Alphadon'' had a very good sense of smell and sight to track down its food, both during the day and night. Its possible whiskers could have also aided in its search for food.

Taxonomy and classification

The type species is ''Alphadon marshi''. Eight other species are known. The species ''Alphadon jasoni'' was originally described by Storer (1991); it was subsequently transferred to the herpetotheriid genus '' Nortedelphys''. Recent phylogenetic studies group it with other northern non-marsupial metatherians such as '' Albertatherium'' and '' Turgidodon''.S. Bi, X. Jin, S. Li and T. Du. 2015. A new Cretaceous metatherian mammal from Henan, China. PeerJ 3:e896 A 2016 phylogenetic analysis is shown below.

References

{{Taxonbar, from=Q3768782 Prehistoric metatherians Late Cretaceous mammals of North America Hell Creek fauna Milk River Formation Fossil taxa described in 1927