Arcusaurus pereirabdalorum, a new sauropodomorph dinosaur from the Early Jurassic of South Africa

Sauropodomorphs form a group of bipedal and quadrupedal herbivorous dinosaurs that reached gigantic proportions in the Jurassic and Cretaceous periods with the likes of Diplodocus, Argentinosaurus and Brachiosaurus. The Upper Elliot Formation of Early Jurassic age in South Africa is home of at least three species of sauropodomorphs. The best known is Massospondylus carinatus, with several specimens uncovered. The two other species are Massospondylus kaarae and Aardonyx celestae, both named very recently, while the status of Gryponyx africanus is unclear, and of Ignavusaurus rachelis, dubious.

Yet, another species, Arcusaurus pereirabdalorum, the smallest of them all, has been added to the list. Scattered remains of at least two individuals, probably juveniles, have been unearthed.
The generic name, which means “Rainbow lizard”, honors the people of South Africa, the “rainbow nation”. Interestingly, Arcusaurus, albeit its Plateosaurus-like deep snout, in the analysis looks very basal and came as a sister taxon of the triassic sauropodomorphs such as Thecodontosaurus and Efraasia. If this were the case, Arcusaurus would be a relict of the primitive Triassic sauropodomorphs that somehow made it to the Jurassic.

Adam M. Yates, Matthew F. Bonnan, and Johann Neveling have described the species in the May 2011 issue of the Journal of Vertebrate Paleontology.

References:

Barrett, P. M. 2009. A new basal sauropodomorph dinosaur from the upper Elliot Formation (Lower Jurassic) of South Africa. Journal of Vertebrate Paleontology 29:1032–1045.

Yates, A. M., M. F. Bonnan, J. Neveling, A. Chinsamy, and M. G. Blackbeard. 2010. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proceedings of the Royal Society B 277:787–794.

Yates, A.M.,  M. F. Bonnan, and J. Neveling. 2011. A New Basal Sauropodomorph Dinosaur from the Early Jurassic of South Africa. Journal of Vertebrate Paleontology, 31(3):610-625.