Vagaceratops Temporal range: Late Cretaceous, 76.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Cast of the holotype skull, Canadian Museum of Nature
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Suborder:	†Ceratopsia
Family:	†Ceratopsidae
Subfamily:	†Chasmosaurinae
Genus:	†Vagaceratops Sampson et al., 2010
Species:	†V. irvinensis
Binomial name
†Vagaceratops irvinensis (Holmes et al., 2001 [originally Chasmosaurus])
Synonyms
Chasmosaurus irvinensis Holmes et al., 2001

Vagaceratops (meaning "wandering (vagus, Latin) horned face", in reference to its close relationship with Kosmoceratops from Utah) is a genus of herbivorous ceratopsian dinosaur. It is a chasmosaurine ceratopsian which lived during the Late Cretaceous period (late Campanian) in what is now Alberta. Its fossils have been recovered from the Upper Dinosaur Park Formation. It is sometimes included in the genus Chasmosaurus as Chasmosaurus irvinensis instead of being recognized as its own genus.

History

In 2010, paleontologist Scott D. Sampson and colleagues named Vagaceratops (from the Dinosaur Park Formation, whose sole species, C. irvinensis, was formerly placed in Chasmosaurus), as well as Kosmoceratops and Utahceratops (from the Kaiparowits Formation) in the same article.^[1] These genera, which were considered unusual compared to typical members of their group, were part of a spate of ceratopsian discoveries in the early 21st century, when many new taxa were named (a 2013 study stated that half of all valid genera were named since 2003, and the decade has been called a "ceratopsid renaissance").^[2][3][4]

Description

Vagaceratops was a medium-sized ceratopsian, reaching 4.5 m (15 ft) in length and weighing 1.2 t (1.3 short tons).^[5] It is known primarily from three fossil skulls. Although the general structure was typical of ceratopsids (i.e. a parrot-like beak, large neck frill, and nasal horn) it has some peculiarities. The skulls are characterized by a reduced supraorbital horn, brow horns that are reduced to low bosses and a larger snout compared to related animals. Vagaceratops had smaller parietal fenestrae than most ceratopsids and had a strange configuration of epoccipitals (bones surrounding the frill). It possessed ten epoccipitals, eight of which were centrally flattened, curved forward and upward and fused together to form a jagged margin along the back of the frill. The frill was shorter and more square-shaped than other chasmosaurines, being wider than it was long.

Classification

Vagaceratops was named by Scott D. Sampson, Mark A. Loewen, Andrew A. Farke, Eric M. Roberts, Catherine A. Forster, Joshua A. Smith, and Alan L. Titus in 2010, and the type species is Vagaceratops irvinensis.^[1] This species was originally described as a species of Chasmosaurus (C. irvinensis) in 2001.^[6] Its relationships remain debated. Vagaceratops has variously been allied with Kosmoceratops^[1] or with Chasmosaurus.^[7][6]

The cladogram below is the phylogeny of the Chasmosaurinae by Brown et al. (2015):^[8]

Recently it has been suggested that Chasmosaurinae had a deep evolutionary split between a Chasmosaurus clade and a Pentaceratops clade. Vagaceratops was hypothesized to be the last member of the Chasmosaurus clade from northern Laramidia, with the last representative of the clade being its close relative Kosmoceratops.^[9]