while its neck frill was moderately large. Unfortunately the specimens were incomplete so it cannot be determined if there were parietal openings in the frill like some other ceratopsians possessed. Classification Brachyceratops belonged to the Centrosaurinae, but its exact placement has been difficult to discover because it is known only from juvenile specimens. In 1997, Scott Sampson and colleagues re-examined Brachyceratops and noted that it is almost certainly the juvenile form of an already known centrosaurine dinosaur. However, because many features that distinguish ceratopsians from each other do not appear until adulthood, exactly which centrosaurine remained unknown, and Sampson et al. classified Brachyceratops as a nomen dubium, or dubious name. In 2007, Michael J. Ryan and colleagues suggested that Brachyceratops was possibly the juvenile form of Styracosaurus ovatus, which has since been reclassified as Rubeosaurus. A 2011 study supported this idea for the most mature specimen of Brachyceratops, USNM 14765, which shows one unique newly evolved feature (apomorphy) in common with Rubeosaurus to the exclusion of other centrosaurines. However, the same study suggested that because the holotype specimen of Brachyceratops is too incomplete and juvenile to preserve any determinable apomorphies, Brachyceratops must be considered a nomen dubium, and cannot be a senior synonym of Rubeosaurus. See also Timeline of ceratopsian research References Centrosaurines Late Cretaceous dinosaurs of North America Nomina dubia Fossil taxa described in 1914 Paleontology in Montana Taxa named by Charles W. Gilmore Campanian genus first appearances Campanian genus extinctions Ornithischian genera