''Alticonodon'' is a genus of extinct mammal from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

of North America. It is the geologically youngest known

eutriconodont Eutriconodonta is an order of early mammals. Eutriconodonts existed in Asia, Africa, Europe, North and South America during the Jurassic and the Cretaceous periods. The order was named by Kermack ''et al.'' in 1973 as a replacement name for the ...

, and is a fairly more specialised animal than earlier representatives of this clade.

Description

''Alticonodon'' is currently a monotypic genus, represented exclusively by ''A. lindoei''. It is known from the

Milk River Formation The Milk River Formation is a sandstone-dominated stratigraphic unit of the Western Canada Sedimentary Basin in southern Alberta, Canada. It was deposited in near-shore to coastal environments during Late Cretaceous (late Santonian to early Campani ...

deposits of the early

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. Campani ...

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

. It is known from two specimens: a dentary fragment bearing two molars, and an isolated lower last molar.

Classification

''Alticonodon'' has been consistently recovered as a triconodontid, and more specifically as an alticonodontine, though the latter term may be redundant in relation to the rest of

Triconodontidae Triconodontidae is an extinct family of small, carnivorous mammals belonging to the order Eutriconodonta, endemic to what would become Asia, Europe, North America and probably also Africa and South America during the Jurassic through Cretaceous ...

Biology

Compared to earlier eutriconodonts, ''Alticonodon'' has molars better specialised for shearing. As eutriconodonts as a group had shearing molars due to their

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

habits, it can be inferred that ''Alticonodon'' was hypercarnivorous. This ecological speciation might have come due to competition with other mammals in the region, such as the various

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 we ...

ns.R. C. Fox. 1969. Studies of Late Cretaceous vertebrates. III. A triconodont mammal from Alberta. ''Canadian Journal of Zoology'' 47:1253-1256

Ecology

The

is a rich fossil environment that covered near-shore and terrestrial deposits. It included a few

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

species like ''

Saurornitholestes ''Saurornitholestes'' ("lizard-bird thief") is a genus of carnivorous dromaeosaurid theropod dinosaur from the late Cretaceous of Canada (Alberta) and the United States (Montana, New Mexico, Alabama, North Carolina, and South Carolina). Two spec ...

'' and ''

Acrotholus ''Acrotholus'' (Greek for "highest dome"- akros meaning highest and tholos meaning dome) is an extinct genus of pachycephalosaur dinosaur that lived during the Santonian of the late Cretaceous, in the Milk River Formation of Canada. The type spe ...

'', as well as a variety of other vertebrate such as the

crocodilian Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...

Gilchristosuchus ''Gilchristosuchus'' (meaning "Gilchrist type_specimen.html" ;"title="he owners of the ranch where the type specimen">he owners of the ranch where the type specimen was foundcrocodile") is an extinct genus of neosuchian crocodyliform.Crocodylifo ...

'', various

turtles Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

and

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...

. The mammalian fauna was primarily dominated by

ns and

multituberculates Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, ...

, as usual for Late Cretaceous mammaliafaunas, but a variety of older taxa remained; besides ''Alticonodon'', there was also the symmetrodont '' Symmetrodontoides'', and '' Potamotelses'' and picopsids. These were the last non-

theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. C ...

n mammals (other than the highly successful multituberculates) in North America, suggesting a relictual element to the region's fauna.

References

{{Taxonbar, from=Q12898680 Eutriconodonts Late Cretaceous mammals of North America Mesozoic mammals of North America Cretaceous animals of North America Fossil taxa described in 1969 Milk River Formation Taxa named by Richard C. Fox Prehistoric mammal genera