[D] Colepiocephale lambei [Su] [sG] [T]
Describer
Sullivan, 2003
Time
Cretaceous Late Campanian
Classification
Ornithischia Genasauria Cerapoda Marginocephalia Pachycephalosauria Pachycephalosauridae
Diet
Herbivore
Fossilsite
[Foremost Formation], Judith River Wedge, Alberta, Canada
Length
1-1,3 Meter
Info
Genus - Typespecies - Skull
Colopiocephale lambei (Sullivan, 2003) > Stegoceras lambei (Sternberg, 1945)
Abstract of: Sullivan, M. (2003) Revision of the dinosaur Stegoceras lambei (Ornithichia, Pachycephalosauridae) Journal of Vertebrate Paleontology: Vol. 23, No. 1, pp. 181–207.
Stegoceras (sensu lato) has been the recipient of a number of species. Most have been placed into synonymy with Stegoceras validum, some have been transferred to other genera (i.e., Gravitholus, Ornatotholus), whereas others have been interpreted as being sexual dimorphs. A parsimonious phylogenetic analysis using 49 characters, which include 9 new cranial characters based on pachycephalosaur frontoparietal domes, now permits a revision of the genus Stegoceras.
This analysis concludes that Stegoceras validum (sensu stricto) is a primitive, incipiently-domed pachycephalosaur that is characterized by a well-developed squamosal shelf and open supratemporal fossae. It is the sister taxon to the fully-domed [Pachycephalosaurinae]. The taxon Ornatotholus browni has a parietal and displays features identical to Stegoceras validum and is therefore a subjective junior synonym. Specimens consisting of flat, paired frontals are immature individuals of Stegoceras validum.
The holotype of “Stegoceras” lambei, and all morphotypes of this species, are unique in the construction of the posterior squamosal region and are placed in a new genus, Colepiocephale.
Colepiocephale lambei is known solely from the Foremost Formation and is the oldest diagnostic pachycephalosaur from North America.
An incomplete, and indeterminate, skull from the upper part of the Milk River Formation (upper Santonian) has the distinction of being the oldest known North American pachycephalosaur.
“Stegoceras” sternbergi lacks a posterior squamosal shelf and has squamosals directed laterally and is placed in a new genus, Hanssuesia, as Hanssuesia sternbergi.
Although the taxon Gravitholus albertae displays some characters (i.e., retention of the posterior squamosals separated by a distinct median parietal) and is similar to Hanssuesia sternbergi in some respects, the holotype is too incomplete for any definitive diagnosis and thus it is considered a nomen dubium. Sphaerotholus is a subjective junior of Prenocephale and the species Sphaerotholus buchholtzae is a subjective junior synonym of Prenocephale edmontonensis.
The taxa [Prenocephale brevis], Prenocephale edmontonensis, and [Prenocephale goodwini], form a monophyletic clade with monotypic Asian taxa Prenocephale prenes and Tylocephale gilmorei as an unresolved sister group. They are united by the possession of a distinct row of nodes on the squamosal and parietals. Tylocephale, if valid, is interpreted as the sister taxon to the Prenocephale clade.
After Sullivan, 2003
†Colepiocephale Sullivan, 2003
†Stegoceras Lambe, 1902; Sternberg, 1945 (in partim)
†Stegoceras Lambe; Sues & Galton, 1987 (in partim)
†Stegoceras Lambe; Baszio, 1997 (in partim)
†Stegoceras Lambe; Williamson & Carr, 2003 (in partim)
†Colepiocephale Sullivan, 2003
†Colepiocephale lambei (Sternberg, 1945) Sullivan, 2003
†Stegoceras lambei Sternberg, 1945
†Stegoceras validum (Lambe, 1902); Sues & Galton, 1987 (in partim)
†Stegoceras validum Lambe, 1918; Marya´nska, 1990
†S. sp. Baszio, 1997 (in partim)
†Stegoceras lambei Sternberg; Williamson & Carr, 2003
†Colepiocephale lambei (Sternberg, 1945) Sullivan, 2003
Sullivan, 2003
Time
Cretaceous Late Campanian
Classification
Ornithischia Genasauria Cerapoda Marginocephalia Pachycephalosauria Pachycephalosauridae
Diet
Herbivore
Fossilsite
[Foremost Formation], Judith River Wedge, Alberta, Canada
Length
1-1,3 Meter
Info
Genus - Typespecies - Skull
Colopiocephale lambei (Sullivan, 2003) > Stegoceras lambei (Sternberg, 1945)
Abstract of: Sullivan, M. (2003) Revision of the dinosaur Stegoceras lambei (Ornithichia, Pachycephalosauridae) Journal of Vertebrate Paleontology: Vol. 23, No. 1, pp. 181–207.
Stegoceras (sensu lato) has been the recipient of a number of species. Most have been placed into synonymy with Stegoceras validum, some have been transferred to other genera (i.e., Gravitholus, Ornatotholus), whereas others have been interpreted as being sexual dimorphs. A parsimonious phylogenetic analysis using 49 characters, which include 9 new cranial characters based on pachycephalosaur frontoparietal domes, now permits a revision of the genus Stegoceras.
This analysis concludes that Stegoceras validum (sensu stricto) is a primitive, incipiently-domed pachycephalosaur that is characterized by a well-developed squamosal shelf and open supratemporal fossae. It is the sister taxon to the fully-domed [Pachycephalosaurinae]. The taxon Ornatotholus browni has a parietal and displays features identical to Stegoceras validum and is therefore a subjective junior synonym. Specimens consisting of flat, paired frontals are immature individuals of Stegoceras validum.
The holotype of “Stegoceras” lambei, and all morphotypes of this species, are unique in the construction of the posterior squamosal region and are placed in a new genus, Colepiocephale.
Colepiocephale lambei is known solely from the Foremost Formation and is the oldest diagnostic pachycephalosaur from North America.
An incomplete, and indeterminate, skull from the upper part of the Milk River Formation (upper Santonian) has the distinction of being the oldest known North American pachycephalosaur.
“Stegoceras” sternbergi lacks a posterior squamosal shelf and has squamosals directed laterally and is placed in a new genus, Hanssuesia, as Hanssuesia sternbergi.
Although the taxon Gravitholus albertae displays some characters (i.e., retention of the posterior squamosals separated by a distinct median parietal) and is similar to Hanssuesia sternbergi in some respects, the holotype is too incomplete for any definitive diagnosis and thus it is considered a nomen dubium. Sphaerotholus is a subjective junior of Prenocephale and the species Sphaerotholus buchholtzae is a subjective junior synonym of Prenocephale edmontonensis.
The taxa [Prenocephale brevis], Prenocephale edmontonensis, and [Prenocephale goodwini], form a monophyletic clade with monotypic Asian taxa Prenocephale prenes and Tylocephale gilmorei as an unresolved sister group. They are united by the possession of a distinct row of nodes on the squamosal and parietals. Tylocephale, if valid, is interpreted as the sister taxon to the Prenocephale clade.
After Sullivan, 2003
†Colepiocephale Sullivan, 2003
†Stegoceras Lambe, 1902; Sternberg, 1945 (in partim)
†Stegoceras Lambe; Sues & Galton, 1987 (in partim)
†Stegoceras Lambe; Baszio, 1997 (in partim)
†Stegoceras Lambe; Williamson & Carr, 2003 (in partim)
†Colepiocephale Sullivan, 2003
†Colepiocephale lambei (Sternberg, 1945) Sullivan, 2003
†Stegoceras lambei Sternberg, 1945
†Stegoceras validum (Lambe, 1902); Sues & Galton, 1987 (in partim)
†Stegoceras validum Lambe, 1918; Marya´nska, 1990
†S. sp. Baszio, 1997 (in partim)
†Stegoceras lambei Sternberg; Williamson & Carr, 2003
†Colepiocephale lambei (Sternberg, 1945) Sullivan, 2003