Diabloceratops (/daɪˌæbloʊˈsɛrətɒps/ dy-AB-loh-SERR-ə-tops) is an extinct genus of centrosaurine ceratopsian dinosaur that lived approximately 81.4-81 million years ago during the latter part of the Cretaceous Period in what is now Utah, in the United States.

The specific name honors Jeffrey Eaton, a paleontologist at Weber State University and long time friend of the lead author Jim Kirkland.

Type specimen UMNH VP 16699 was collected by Don DeBlieux in 2002, at the Last Chance Creek locality of this formation, in intraclastic sandstone that was deposited during the Campanian stage of the Cretaceous period.

Kirkland and DeBlieux saw this as an indication that the earlier species were not together included in some single natural group but instead presented a gradual sequence of ever more derived forms, increasingly closer related to the Ceratopsidae.

[2] During the time that Diabloceratops lived, the Western Interior Seaway was at its widest extent, almost completely isolating southern Laramidia from the rest of North America.

[12] Diabloceratops shared its paleoenvironment with other dinosaurs, such as the hadrosaur Acristavus gagslarsoni,[13][14] and the lambeosaur Adelolophus hutchisoni,[15] unnamed ankylosaurs and pachycephalosaurs, and the theropod Lythronax argestes, which was likely the apex predator in its ecosystem.

[16][17][18] Vertebrates present in the Wahweap Formation at the time of Diabloceratops included freshwater fish, bowfins, abundant rays and sharks, turtles like Compsemys, crocodilians,[19] and lungfish.

[23] Invertebrate activity in this formation ranged from fossilized insect burrows in petrified logs[24] to various mollusks, large crabs,[25] and a wide diversity of gastropods and ostracods.