Genus: Polycotylus COPE, 1869
Etymology: Greek, polys, “much, many”, Greek, kotyle, “hollow, cup”, + us: Very cupped vertebrae.

Species: latipinnis COPE, 1869
Etymology:

Referred material:

MARTIN, SCHUMACHER PARRIS & GRANDSTAFF, 1998

Locality: SDSM V9011, South Dakota.

Horizon: 1 meter below the Niobrara/Pierre contact.

Biostratigraphy:

Age: Late Cretaceous.

Material:

SDSM 23020: Nearly complete articulated skeleton.
Note: Paleopathology, humerus shows avascular necrosis (ROTHSCHILDS & STORRS, 2003)