Medusaceratops is an extinct genus of centrosaurine ceratopsian dinosaur known from the Late Cretaceous Judith River Formation (middle Campanian stage) of Montana, northern United States.

Trexler and Sweeney (1995) reinterpreted the spikes as eye-socket horncores and noted their similarity to those of the nomen dubium Ceratops montanus from a nearby area, however, could not refer the bonebed material to any valid existing taxon.

The bonebed is located at approximately the same level as the holotype of Albertaceratops, dating to 77.5 million years ago, to the middle Campanian stage of the Late Cretaceous.

Chiba et al. in 2017 described new material of Medusaceratops from the Mansfield Bonebed, found in 2011 and 2012 by David Trexler, indicating the presence of traits that were characteristic of Centrosaurinae in the skeleton of M. lokii.

The phylogenetic analysis conducted by the authors indicated that Medusaceratops was not a member of Chasmosaurinae after all, but rather an early centrosaurine ceratopsid that was more closely related to Centrosaurini and Pachyrhinosaurini than Nasutoceratopsini.

[4] Among valid ceratopsids from the Judith River Formation, Medusaceratops can be directly distinguished from centrosaurine Avaceratops,[3] and chasmosaurines Judiceratops and Spiclypeus[5] based on its unique frill ornamentation.

[1][3] The cladogram presented below follows a phylogenetic analysis by Chiba et al. (2017) who redescribed Medusaceratops as a centrosaurine:[3] Diabloceratops eatoni Machairoceratops cronusi Avaceratops lammersi (ANSP 15800)

Nasutoceratops titusi Malta new taxon Xenoceratops foremostensis Sinoceratops zhuchengensis Wendiceratops pinhornensis Albertaceratops nesmoi Medusaceratops lokii Centrosaurini Pachyrhinosaurini