Alticonodon

Alticonodon
Temporal range: Santonian-Campanian, 84.5–83.5 Ma
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Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: †Eutriconodonta
Family: †Triconodontidae
Subfamily: †Alticonodontinae
Genus: †Alticonodon
Fox, 1969
Species:
†A. lindoei
Binomial name
†Alticonodon lindoei
Fox, 1969

Alticonodon is a genus of extinct mammal from the Late Cretaceous of North America. It is one of the geologically youngest known eutriconodonts, and is a fairly more specialised animal than earlier representatives of this clade.[1]

Description

Alticonodon is currently a monotypic genus, represented exclusively by A. lindoei. It is known from the Milk River Formation deposits of the early Campanian of Alberta, Canada. 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,[2] though the latter term may be redundant in relation to the rest of Triconodontidae.[3]

Biology

Compared to earlier eutriconodonts, Alticonodon has molars better specialised for shearing.[1] As eutriconodonts as a group had shearing molars due to their carnivorous habits,[4] it can be inferred that Alticonodon was hypercarnivorous.

This ecological specialisation might have come due to competition with other mammals in the region, such as the various metatherians.[1]

Ecology

The Milk River Formation is a rich fossil environment that covered near-shore and terrestrial deposits. It included a few dinosaur species like Saurornitholestes and Acrotholus, as well as a variety of other vertebrate such as the crocodilian Gilchristosuchus, various turtles and fish.

The mammalian fauna was primarily dominated by metatherians and multituberculates, 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-therian mammals (other than the highly successful multituberculates) in North America, suggesting a relictual element to the region's fauna.

References

  1. ^ a b c R. C. Fox. 1969. Studies of Late Cretaceous vertebrates. III. A triconodont mammal from Alberta. Canadian Journal of Zoology 47:1253-1256
  2. ^ L. C. Gaetano and G. W. Rougier. 2011. New materials of Argentoconodon fariasorum (Mammaliaformes, Triconodontidae) from the Jurassic of Argentina and its bearing on triconodont phylogeny. Journal of Vertebrate Paleontology 31(4):829-843 [R. Benson/R. Benson]
  3. ^ Thomas Martin, Jesús Marugán-Lobón, Romain Vullo, Hugo Martín-Abad, Zhe-Xi Luo & Angela D. Buscalioni (2015). A Cretaceous eutriconodont and integument evolution in early mammals. Nature 526, 380–384. doi:10.1038/nature14905
  4. ^ Zofia Kielan-Jaworowska, Richard L. Cifelli, Zhe-Xi Luo (2004). "Chapter 7: Eutriconodontans". Mammals from the Age of Dinosaurs: origins, evolution, and structure. New York: Columbia University Press. pp. 216–248. ISBN 0-231-11918-6.