Species: alexandrae WELLES, 1943
Etymology:

Holotype: UCMP 33912

Locality: UC V3735 on the property of the Sun Ray Gypsum Mine, 2475 feet S 68'W of the mine buildings and in the bottom of the S. Fork of the first ravine S of Moreno Gulch, 900 ft E., 1500 feet S of NW. cor., Sec. 13, T 14S, R 11E., MDB and M., USGS Panoche Quadrangle, 22 miles due west of Mendota, Fresno County, California.

Horizon: Moreno Formation.

Biostratigraphy:

Age: Maastrichtian Stage, uppermost Senonian subepoch, Gulf Epoch, Late Cretaceous.

Material: Skull and a nearly complete skeleton, lacking only small parts of the skull, pectoral girdle, paddles, vertebral processes, and the last few caudal vertebrae.

Skull after Welles (1943): A) Dorsal; B) With closed jaws and C) with open jaws.