Barosaurus lentus, Marsh OC, 1890

Marsh, O. C., 1890, Description of new dinosaurian reptiles, American Journal of Science 39 (229), pp. 81-87 : 85-86

Barosaurus lentus , gen. et sp. nov.

A new genus of the Sauropoda , is indicated by various remains of a very large reptile secured by the writer during the past season. The most characteristic portions examined are the caudal vertebrae, which in general form resemble those of Diplodocus . They are concave below, as in the caudals of that genus, but the sides of the centra are also deeply excavated.

In the anterior caudals, this excavation extends nearly or quite through the centra, a thin septum usually remaining. In the median caudals, a deep cavity on each side exists, as shown in figures 1 and 2, on page 86.

On the distal caudals, the lateral cavity has nearly or quite disappeared. All the caudal vertebrae are proportionally shorter than in Diplodocus , and their chevrons have no anterior projection, as in that genus.

The remains on which the present description is based are from the Atlantosaurus beds of Dakota, about two hundred miles further north than this well-marked horizon has hitherto been recognized.