Arctosaurus is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of extinct reptile

Reptile

Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

 originally classified as a small reptile of unknown affinities, but was often classified as a sauropodomorph dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

 in the years to follow. Although it has also been classified as a theropod, recent review finds that the similarities it shares with theropods are spread throughout several groups of Late Triassic

Late Triassic

The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...

 reptiles, and so it cannot be assigned any more specifically than to Archosauriformes

Archosauriformes

Archosauriformes is a clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Late Permian...

. Other authors have suggested trilophosaur

Trilophosaur

Trilophosaurs were lizard-like Triassic diapsid reptiles related to the archosaurs. The best known genus is Trilophosaurus, a herbivore up to 2.5 meters long. It had a short, unusually heavily-built skull, equipped with massive, broad flattened cheek teeth with sharp shearing surfaces for cutting...

ian affinities. It is based on

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 a neck vertebra that was found on Cameron Island

Cameron Island

Cameron Island is one of the Canadian arctic islands in Nunavut, Canada. Located in the Arctic Ocean, close to Bathurst Island, it has an area of . Île Vanier lies immediately to the south, across the Arnott Strait.- Commercial oil production :...

, Nunavut

Nunavut

Nunavut is the largest and newest federal territory of Canada; it was separated officially from the Northwest Territories on April 1, 1999, via the Nunavut Act and the Nunavut Land Claims Agreement Act, though the actual boundaries had been established in 1993...

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, in Late Triassic

Late Triassic

The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...

-age rocks.

External links

• Arctosaurus in The Dinosaur Encyclopaedia at Dino Russ's Lair