Avaceratops is a genus of small herbivorous ceratopsian dinosaurs which lived during the late Campanian in what are now the Northwest United States.

The first remains of Avaceratops were found by Eddie Cole in the Judith River Formation of Montana, in 1981, on land of the Careless Creek Ranch, owned by rancher Arthur J.

The type specimen might represent a juvenile or a subadult individual, Dodson in 1986 being inclined to consider it almost fully grown.

[3] Kenneth Carpenter made a reconstruction of the skull, a cast of which was by Leroy Glenn combined with restored parts of the postcranial skeleton to create a mount that in 1986 was displayed in the Academy of Natural Sciences in Philadelphia; a copy of this skeletal mount was donated to the Upper Musselshell Valley Historical Museum in Harlowton.

A raised area at the base of the squamosal divides it into two equal halves, whereas more derived species have an enlarged top part.

Also the parietals are probably lacking fenestrae which are typical of many other genera except Triceratops, resulting in a solid frill,[1] although damage to the holotype allows for a small opening to be present.

[3] Avaceratops was by Dodson in 1986 assigned to the Ceratopsidae within the Ceratopsia (both names being derived from Ancient Greek for 'horned face'), a group of herbivorous dinosaurs with parrot-like beaks which thrived in what are now North America and Asia, during the Cretaceous Period.

A phylogenetic analysis performed by Sampson et al. (2013) found that Avaceratops was the sister taxon of the new genus Nasutoceratops, described and named in 2013.

[8] The cladogram presented below follows a phylogenetic analysis by Chiba et al. (2017):[10] Diabloceratops eatoni Machairoceratops cronusi Avaceratops lammersi (ANSP 15800)