Fresnosaurus drescheri was named by Welles (1943). Its type specimen is CIT 2758, a set of postcrania (coracoids, humerus, pelvis, femora, and disarticulated paddle bones), and it is a 3D body fossil. Its type locality is LACM (CIT) 346, which is in a Maastrichtian marine horizon in the Moreno Formation of California.