| Mercuriceratops | |
|---|---|
| |
| A restoration of Mercuriceratops gemini | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| clade: | Dinosauria |
| Order: | †Ornithischia |
| Family: | †Ceratopsidae |
| Subfamily: | †Chasmosaurinae |
| Genus: | †Mercuriceratops Ryan et al., 2014 |
| Binomial name | |
| †Mercuriceratops Ryan et al., 2014 | |
Mercuriceratops is an extinct ceratopsid dinosaur known from the Late Cretaceous of Canada and the United States. The only type species it contains is Mercuriceratops gemini.
Discovery[]
In 2007, Triebold Paleontology Inc found The holotype (ROM 64222) in Fergus County, Montana.
In 2014, the type species Mercuriceratops gemini was described by Michael Ryan, David Evans, Philip John Currie and Mark Loewen. The generic name merges the name of the Roman god Mercury, with ~ceratops, an usual latin suffix in ceratopsian names. The specific name is that of the constellation Gemini, named after the twins Castor and Pollux, for the reference to the similar specimens the species is based on.
Description[]
The describers estimated that Mercuriceratops was the same size as Chasmosaurus. The holotype squamosal has a length of 793 millimetres (31.2 in; 2.602 ft). Ryan established a single autapomorphy, unique derived trait, of Mercuriceratops. The squamosal possesses a rear branch that is narrowed and rod-shaped instead of being blunt, triangular and tapering, the normal chasmosaurine form, or broadly rounded as with Triceratops. The narrowing is caused by an indentation of the outer rim of the squamosal. The squamosal carries at least six, and perhaps as many as eight, episquamosals, osteoderms on the frill rim. Based on the narrow form of the squamosal, it was deduced that the inner shield bones, the parietals, were very wide and pierced by enormous parietal fenestrae. Mercuriceratops was placed in the Chasmosaurinae. It is the oldest chasmosaurine known from Canada, and the first pre-Maastrichtian ceratopsid to have been collected on both sides of the Canada–US border. Though the profile of the Mercuriceratops squamosal suggests it was a transitional form between older rectangular squamosals of centrosaurine shape and later triangular squamosals, the describers rejected this hypothesis because juvenile centrosaurines do not show such a transitional phase during their ontogeny.
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