In Depth
A genus of pachycephalosaurid dinosaur, Sphaerotholus has been raising a few questions as to its validity. The type species, S. goodwini is based upon only two very partial skull fossils. S. edmontonensis is based only upon three partial skull domes. This has led some to speculate that the genus is dubious and indifferent to S. goodwini, though others contend that it can be differentiated from the S. goodwini by a pair of hornlets on the back.
Of most interest though is the species S. buchholtzae which has been suggested to be synonymous with the genus Prenocephale from Asia. If this species of Sphaerotholus does actually represent specimens of Prenocephale, then this would make Prenocephale the most geographically widespread genus of pachycephalosaurid dinosaur so far known to us. However, Sphaerotholus buchholtzae is only known from a partial skull, and the level of preservation of this skull makes it very difficult to be certain if S. buchholtzae is synonymous with Prenocephale. If true however, then only this species of Sphaerotholus would be synonymous with Prenocephale, and not the whole genus as some have erroneously claimed. The only way the full Sphaerotholus genus could be synonymised with Prenocephale is if specimens of the type species S. goodwini can be definitively proven to be the same as Prenocephale.
Further Reading
- A study of the tro�dont dinosaurs with a description of a new genus and four new species. - Bulletin of the American Museum of Natural History 82(5): 115-149. - B. Brown & E. M. Schlaikjer - 1943. - A new genus of highly derived pachycephalosaurian from western North America. - Journal of Vertebrate Paleontology 22(4):779-801. - T. E. Carr & T. D. Williamson - 2002. - Revision of the dinosaur Stegoceras Lambe (Ornithischia, Pachycephalosauridae). - Journal Of Vertebrate Paleontology 23 (1): 181–207. - Robert M. Sullivan - 2003. - Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA. - Cretaceous Research 31: 274-284. Nicholas R. Longrich, Julia, T. Sankey & Darren Tanke - 2010.
