Genus: Ceratosaurus MARSH, 1884
Etymology: Greek kerat (keras) “horn” and Greek sauros for lizard.

Species: nasicornis MARSH, 1884

Holotype: USNM 4735

Locality: Marsh-Felch’s YPM Quarry 1, Garden Park, Sec. 28, T17S, R70W, Canyon City, Fremont County, Colorado.

Horizon: Salt Wash Member, Morrison Formation.

Biostratigraphy: Zone 2.

Age: Comobluffian age, Kimmeridgian Stage, uppermost Malm Epoch, Late Jurassic.

Material: Skull, lower jaws, atlas, axis, 7 cervical vertebrae, 12 fragmentary dorsal vertebrae, complete sacrum, 50 caudal vertebrae, 20 chevrons, last thoracic rib, fragmentary cervical vertebrae, left scapula, left ulna, left radius, 4 left metacarpals, 3 left phalanges, 3 right metacarpals, 1 right phalanges, ilia, pubes lacking distal ends, ischia lacking distal ends, femora, right tibia, right fibula, right astragalus, right calcanum, 1 tarsal bones of distal left row, left pathological metatarsals, right metatarsals, 1 terminal left phalanx of digit IV, several skin ossicles.

Note: Left ulna has a pathology (pers. observation).

Species: dentisulcatus MADSEN & WELLES, 2000
Etymology: In reference to the persistent, parallel grooves on the medial surface of the premaxillary teeth and the anterior 3 teeth in the dentary.

Holotype: UMNH 5278

Locality: Cleveland-Llyod Dinosaur Quarry, approximately 20 miles south of Price, SE 1/4, SE 1/4, Sec. 21, T17S, R11E, SLBM. lat 39°19’00", Long. 110°41’15"W, San Rafael Swell Area, Carbon County, Utah.

Horizon: Brushy Basin Member, Morrison Formation.

Biostratigraphy: Zone 3.

Age: Upper Part, Comobluffian age, Kimmeridgian Stage, uppermost Malm Epoch, Late Jurassic.

Referred material:

UUVP 158: Left dentary.
Note: Pathology, the right dentary has a diastma that may be pathologic like “Labrosaurus ferox”.