What is "arctosaurus"

Arctosaurus (meaning "arctic lizard") is an extinct genus of reptile originally classified as a small reptile of unknown affinities, but was often classified as a sauropodomorph dinosaur 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 reptiles, and so it cannot be assigned any more specifically than to Archosauriformes. Other authors have suggested trilophosaurian affinities. It is based on a neck vertebra that was found on Cameron Island, Nunavut, Canada, in Late Triassic-age rocks.