Name: Sphaerotholus.
Phonetic: Sfay-ro-fo-luss.
Named By: T.‭ ‬E.‭ ‬Carr‭ & ‬T.‭ ‬D.‭ ‬Williamson‭ ‬-‭ ‬2002.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Ornihischia,‭ ‬Marginocephalia,‭ ‬Pachycephalosauridae.
Species: S.‭ ‬goodwini‭ (‬type‭)‬,‭ ‬S.‭ ‬edmontonensis,‭ ‬S.‭ ‬buchholtzae‭?
Diet: Herbivore.
Size: Uncertain due to lack of fossil remains.
Known locations: Canada,‭ ‬Alberta‭ ‬-‭ ‬Horsehoe Canyon Formation.‭ ‬USA,‭ ‬Montana‭ ‬-‭ ‬Hell Creek Formation,‭ ‬New Mexico‭ ‬-‭ ‬Kirtland Formation.
Time period: Campanian/Maastrichtian of the Cretaceous.
Fossil representation: Partial skull domes.

       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.


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