Colepiocephale

{{Short description|Extinct genus of dinosaurs}} {{speciesbox | fossil_range = Late Cretaceous, {{Fossil range|80.45|78}} | image = Colepiocephale skull.jpg | image_caption = Holotype skull CMN 8818 | genus = Colepiocephale | parent_authority = Sullivan, 2003<ref name="sullivan2003"/> | species = lambei | authority = (Sternberg, 1945)<ref name="sternberg1945"/> | synonyms= * ''Stegoceras lambei'' {{small|Sternberg, 1945}} }}

'''''Colepiocephale''''' (meaning "knucklehead") is a genus of pachycephalosaurid dinosaur from Late Cretaceous (middle Campanian stage) deposits of Alberta, Canada. It was collected from the Foremost Formation. The type species, ''C. lambei'', was originally described by Sternberg in 1945 as ''Stegoceras lambei'', and later renamed by Sullivan in 2003. ''C. lambei'' is a domed pachycephalosaur characterized principally by the lack of a lateral and posteriosquamosal shelf, a steeply down-turned parietal, and the presence of two incipient nodes tucked under the posterior margin of the parietosquamosal border.<ref name="sullivan2003"/>

==History of naming== [[File:Colepiocephale lambei.png|thumb|left|Life reconstruction]] In 1923, a partial skull was collected from the Oldman Formation of Alberta by E.J. Whitaker, as the only fossil found at a locality {{cvt|3|mi|km|order=flip}} below Bow Island ferry along the South Saskatchewan River and {{cvt|200|-|300|ft|m|order=flip}} below the top of the Oldman Formation. It was acquired by the Geological Survey of Canada where it gained the accession number GSC No. 8818.<ref name="sternberg1945"/><ref name="brown1943"/> GSC 8818 was first described by American palaeontologists Barnum Brown and Erich Maren Schlaikjer in 1943 as a specimen of the pachycephalosaur ''Troodon validus'', which had earlier been given the name ''Stegoceras validus'' but was not believed to be a distinct genus by Brown and Schlaijker.<ref name="brown1943"/> This identification was disputed by American palaeontologist Charles Mortram Sternberg in 1945, who showed that ''Troodon'', for a time believed to be a pachycephalosaur, was instead a carnivorous theropod, who as a result revived ''Stegoceras'' as well as named the new family Pachycephalosauridae to house pachycephalosaurs. Sternberg also recognized that GSC 8818 was a separate species from ''S. validus'', and created the new species ''Stegoceras lambei'' with GSC 8818 as the holotype. The species name was in honour of the deceased Canadian palaeontologist Lawrence M. Lambe.<ref name="sternberg1945"/>

The separation of ''S. lambei'' from ''S. validum'' was not supported by the 1987 study of American palaeontologists Hans-Dieter Sues and British palaeontologist Peter Galton, who considered the two species as synonyms.<ref name="sues1987"/> However, American paleontologists Thomas E. Williamson and Thomas D. Carr chose to retain ''S. lambei'' as separate in 2002, finding it as a close relative of ''S. validum'' and ''Stegoceras sternbergi'' and more distantly related to ''Stegoceras breve''.<ref name="williamson2002"/> These species and the general taxonomy of ''Stegoceras'' was reviewed in 2003 by American palaeontologist Robert M. Sullivan, who found that ''S. lambei'' was closer to ''Pachycephalosaurus'' than ''Stegoceras'' and chose to give it the new genus name ''Colepiocephale''. The name is a combination of the Latin word ''colepium'', "knuckle", in reference to the curled knuckle-like appearance of the dome, and the Ancient Greek κεφαλή (''cephale'') meaning "head". The accession number for the holotype had also changed by this time to CMN 8818, as it was now held in the Canadian Museum of Nature. Along with the holotype, 13 other specimens were referred to ''Colepiocephale lambei'', held variously in the CMN, Royal Ontario Museum, Royal Tyrrell Museum of Palaeontology, and the University of Alberta Laboratory of Vertebrate Palaeontology, and all these specimens come from the Foremost Formation, part of the historical Oldman Formation. Being from the Foremost, ''Colepiocephale'' would be one of the oldest pachycephalosaurs from North America, from the early Campanian.<ref name="sullivan2003"/>

A redescription and revision of ''Colepiocephale'' was published by Canadian palaeontologists Ryan K. Schott and David C. Evans, and Williamson, Carr and Mark B. Goodwin in 2009, including identifying the first specimen of the taxon from the Judith River Formation of Montana. The distinctiveness of ''Colepiocephale'' was supported, as well as its status as an older genus, with the Judith River specimen from sediments in Kennedy Coulee that are approximately 78 million years old, while the specimens of the Foremost are between 79.79 and 80.45 million years old.<ref name="schott2009"/><ref name="thompson2024"/> 31 specimens from the Foremost are identifiable as pachycephalosaurs, and all of them, where complete enough, show the features diagnostic to ''Colepiocephale'' suggesting it was the only pachycephalosaur within its time and space interval. This gives the possibility that other age-equivalent specimens from Judith River could be part of the genus, though their identification is uncertain.<ref name="schott2009"/>

==References== {{Reflist|refs= <ref name="brown1943">{{cite journal|last1=Brown|first1=B.|author-link1=Barnum Brown|last2=Schlaikjer|first2=E.M.|author-link2=Erich Maren Schlaikjer|year=1943|title=A study of the troödont dinosaurs with the description of a new genus and four new species|journal=Bulletin of the American Museum of Natural History|volume=82|issue=5|pages=115–150}}</ref> <ref name="sternberg1945">{{cite journal|last=Sternberg|first=C.M.|author-link=Charles Mortram Sternberg|year=1945|title=Pachycephalosauridae proposed for dome-headed dinosaurs, ''Stegoceras lambei'', n. sp., described|journal=Journal of Paleontology|volume=19|issue=5|pages=534–538}}</ref> <ref name="sues1987">{{cite journal|last1=Sues|first1=H.D.|author-link1=Hans-Dieter Sues|last2=Galton|first2=P.M.|author-link2=Peter Galton|year=1987|title=Anatomy and classification of the North American Pachycephalosauria (Dinosauria: Ornithischia)|journal=Palaeontographica Abteilung A|volume=198|pages=1–40}}</ref> <ref name="williamson2002">{{cite journal|last1=Williamson|first1=T.E.|last2=Carr|first2=T.D.|author-link2=Thomas Carr (paleontologist)|year=2002|title=A new genus of derived pachycephalosaurian from western North America|journal=Journal of Vertebrate Paleontology|volume=22|issue=4|pages=779–801|doi=10.1671/0272-4634(2002)022[0779:ANGODP]2.0.CO;2|s2cid=86112901}}</ref> <ref name="sullivan2003">{{cite journal|last=Sullivan|first=R.M.|author-link=Robert M. Sullivan|year=2003|title=Revision of the dinosaur ''Stegoceras'' Lambe (Ornithischia, Pachycephalosauridae)|journal=Journal of Vertebrate Paleontology|volume=23|pages=181–207|doi=10.1671/0272-4634(2003)23[181:rotdsl]2.0.co;2}}</ref> <ref name="schott2009">{{cite journal|last1=Schott|first1=R.K.|last2=Evans|first2=D.C.|author-link2=David C. Evans (paleontologist)|last3=Williamson|first3=T.E.|last4=Carr|first4=T.D.|author-link4=Thomas Carr (paleontologist)|last5=Goodwin|first5=M.B.|year=2009|title=The anatomy and systematics of ''Colepiocephale lambei'' (Dinosauria: Pachycephalosauridae)|journal=Journal of Vertebrate Paleontology|volume=29|issue=3|pages=771–786|doi=10.1671/039.029.0329|bibcode=2009JVPal..29..771S }}</ref> <ref name="thompson2024">{{cite journal|last1=Thompson|first1=M.G.W.|last2=Cullen|first2=T.M.|last3=Evans|first3=D.C.|author-link3=David C. Evans (paleontologist)|last4=Schröder-Adams|first4=C.|last5=Ryan|first5=M.J.|year=2024|title=Multi-Proxy paleoenvironmental and paleoecological reconstruction of the Foremost Formation (Upper Cretaceous, Campanian) of Alberta|journal=PALAIOS|volume=39|issue=12|pages=425–443|doi=10.2110/palo.2022.061|bibcode=2024Palai..39..425T }}</ref> }}

Category:Pachycephalosauria Category:Dinosaur genera Category:Campanian dinosaurs Category:Fossil taxa described in 2003 Category:Dinosaurs of Canada