Species: wellesi CARPENTER, 1996
Etymology: In honor of Sam Welles for his life-long work on Cretaceous plesiosaurs.

Holotype: CM 2815

Locality: Near Connanp Creek, Rattlesnake Hills, Natrona County, Wyoming.

Horizon: Belle Fourche Shale.

Biostratigraphy:

Age: Lowermost Cenomanian Stage, Lower Upper Middle Gallic Subepoch, Lowermost Gulf Epoch, Middle Cretaceous.

Material: Complete skull with mandible, disarticulated cervicals, right (?) coracoid.