Exostinus

Exostinus Temporal range: Maastrichtian–Oligocene PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Anguimorpha
Family:	Xenosauridae
Genus:	†Exostinus Cope, 1873
Type species
†Exostinus serratus Cope, 1873
Other species
Exostinus lancensis Gilmore, 1928
Synonyms[1]
Harpagosaurus parvus Gilmore, 1928 Prionosaurus regularis Gilmore, 1928

Exostinus is an extinct genus of xenosaurid lizard from the Late Cretaceous to Oligocene of the western United States. It was named in 1873 by Edward Drinker Cope as Exostinus serratus for jaw and skull bones found in the White River Formation of Colorado showing distinguishing cranial scutes. Material of E. serratus is also known from the Brule Formation, also Middle Oligocene in age, but in Wyoming. A second species, E. lancensis was named in 1928 by Charles W. Gilmore and is also known from skull and jaw bones, from the Maastrichtian Hell Creek, Lance and Fort Union Formations, and the Paleocene Tongue River Formation. Other species named by Gilmore are now considered synonyms of E. lancensis.^[1]