Medusaceratopslokii

Overview: Medusaceratops lokii was discovered in the Late Cretaceous Judith River Formation of Montana in the late 20th Century, but due to confusion as to what it actually was, it wasn't named until 2010, being dubbed a “trickster” by the scientists who described it. Far from the only ceratopsid in Late Cretaceous Montana, this "trickster" can be distinguished from its kin by its thick "snake-like" spikes on its frill, which inspired its name.

Discovery: Medusaceratops lokii was discovered in the Mansfield Bonebed on the west side of Kennedy Coulee in the Milk River Natural Area, near Havre, Hill County of Montana in 1993 and was thought to be the remains of a Styracosaurus. In 1995, it was re-reported as possibly belonging to the dubious taxon Ceratops montanus. In 2003, Michael J. Ryan unofficially named it Medusaceratops in a dissertation, but later referred it to Albertaceratops, which he described in 2007. Subsequently, Ryan realized that the bones from the Mansfield Bonebed did not belong to Albertaceratops, and in 2010 Ryan, along with coauthors Anthony P. Russell and Scott Hartman, officially described and named Medusaceratops lokii as its own distinct taxon. Medusaceratops is Greek, meaning “Medusa horned face”, from the name Medusa combined with “ceratops” meaning “horned face”. Medusa refers to the character from Greek mythology who had snakes for hair and who’s gaze could turn people to stone. This was chosen because of Medusaceratops’s thick “snake-like” spikes on its frill. The species name lokii refers to Loki, the trickster god from Norse mythology, chosen because of the fossil’s history of tricking scientists regarding its identification.

Evolution, Description, and Ecology: Medusaceratops lived in the Judith River Formation of what is now Montana in the Late Cretaceous period, about 77.5 million years ago, and was a ceratopsid ceratopsian, a group of charismatic herbivorous dinosaurs that were fully quadrupedal and had horns and frills on their heads. In true trickster form, where Medusaceratops falls within Ceratopsidae has been more difficult to determine. When it was named, it was classified as an early chasmosaurine, Chasmosaurinae being a subfamily of ceratopsians which generally had large frills, small nasal horns, and large horns above the eyes. This group includes famous genera such as Chasmosaurus, Pentaceratops, and Triceratops. However, with the discovery of more material, Medusaceratops has been reclassified as an early member of the subfamily Centrosaurinae, which typically had shorter frills, often ornamented with paired spikes, shorter or absent brow horns, and longer nasal horns, and included such genera as Centrosaurus, Styracosaurus, and Pachyrhinosaurus, as well as Albertoceratops, which Medusaceratops was once classified as. The differences between centrosaurines and chasmosaurines in their early stages seem to be less pronounced however, as basal centrosaurines like Medusaceratops actually had shorter nasal horns and longer brow horns.

Medusaceratops had at least five pairs of spikes on its frill, which were thick and “snake-like” and curved out to the sides and downward. Its frill had two small holes in it, which would have been covered by skin and probably brightly colored, most likely used for display. Its horns were also probably display features, though they also could have doubled as a defense against predators like the tyrannosaurids Daspletosaurus and Gorgosaurus. At about 6 meters (19.7 ft) long, Medusaceratops was probably too large and heavily defended for smaller carnivores like Troodon, Saurornitholestes, and Dromaeosaurus to tackle, though these may have preyed on Medusaceratops hatchlings and juveniles if given the chance. Like all ceratopsids, Medusaceratops was an herbivore and probably fed low to the ground. Other herbivores from the Judith River Formation included fellow ceratopsids Avaceratops, Judiceratops, and Mercuryceratops, hadrosaurs such as Corythosaurus and the highly common Brachylophosaurus, and ankylosaurs such as Zuul.

Extinction and Legacy: As the Late Cretaceous progressed, Medusaceratops was eventually replaced by a variety of other ceratopsians, both centrosaurines and chasmosaurines, which came in great variety, and which lasted (as a group) to the end of the Age of Dinosaurs. Medusaceratops can be seen in the Wyoming Dinosaur Center in Thermopolis, WY, USA.