Centrosaurinae

Centrosaurines Temporal range: Late Cretaceous, 80.8–66 Ma PreЄ Є O S D C P T J K Pg N
Centrosaurus "nasicornus" skeleton, Palaeontological Museum Munich
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Order:	†Ornithischia
Family:	†Ceratopsidae
Subfamily:	†Centrosaurinae Lambe, 1915
Type species
Centrosaurus apertus Lambe, 1904
Subgroups
Albertaceratops Diabloceratops Machairoceratops Monoclonius Medusaceratops Sinoceratops Wendiceratops Xenoceratops Nasutoceratopsini Avaceratops Nasutoceratops Yehuecauhceratops Eucentrosaura Centrosaurini Centrosaurus Coronosaurus Rubeosaurus Spinops Styracosaurus Pachyrhinosaurini
Synonyms
Pachyrhinosaurinae Sternberg, 1950 Monocloniinae Nopcsa, 1923

Centrosaurinae (Greek: pointed lizards) is a subfamily of ceratopsid dinosaurs, a group of large quadrupedal ornithiscians. Centrosaurinae was named by paleontologist Lawrence Lambe in 1915, with Centrosaurus as the type genus. The centrosaurines are further divided into three tribes: the Nasutoceratopsini, the Centrosaurini, and the Pachyrhinosaurini by Ryan et al (2016).^[1] Nasutoceratopsins are defined as centrosaurines closer to Nasutoceratops titusi than to Centrosaurus apertus and centrosaurins are defined as centrosaurines (more specifically eucentrosaurans) closer to Centrosaurus apertus than to Pachyrhinosaurus canadensis. The only division used up until then was Pachyrhinosaurini which was defined as centrosaurines closer to Pachyrhinosaurus canadensis than to Centrosaurus apertus. Centrosaurine fossil remains are known primarily from the northern region of Laramidia (modern day Alberta, Montana, and Alaska) but isolated taxa have been found in China and Utah as well.^[2] Defining features of centrosaurines include a large nasal horn, short supratemporal horns, and an ornamented frill projecting from the back of the skull.^[3] With the exception of Centrosaurus apertus, all adult centrosaurines have spike-like ornaments midway up the skull.^[4] Morphometric analysis shows that centrosaurines differ from other ceratopsian groups in skull, snout, and frill shapes.^[5] There is evidence to suggest that male centrosaurines had an extended period of adolescence and sexual ornamention did not appear until adulthood.^[3]

Classification

The cladogram presented here follows a 2016 phylogenetic analysis by Rivera-Sylva et al..^[6]

The cladogram presented below follows a phylogenetic analysis by Chiba et al. (2017):^[7]

Biogeography

Centrosaurine fossils have mostly been found in Western North America (Alberta, Montana, & Alaska).^[2] In the United States, two taxa, Diabloceratops and Machairoceratops, have been found as far south as Utah. Yehuecauhceratops is a nasutoceratopsin from Coahuila, Mexico and the southernmost occurrence of a centrosaurine in North America. ^[2] No centrosaurine fossils had been uncovered outside Western North America until 2010 when Sinoceratops zhuchengensis was discovered in the Shandong Province of China.^[8] Some authors question the placement of Sinoceratops within Centrosaurinae, however. All other Late Cretaceous dinosaur groups from North America have been found in Asia as well so the initial absence of Asian centrosaurines had been surprising.^[8] The current evidence suggests that Centrosaurinae originated in Laramidia 90-80 million years ago.^[2] This means Sinoceratops would have migrated to China from North America.^[1] Some hypothesize that centrosaurines originated in the south Laramidia and only later radiated north.^[9]

Body Size

Compared to their sister group, Chasmosaurinae, centrosaurines are relatively small. The primitive Sinoceratops zhuchengensis is an exception, with an estimated skull length of 180 cm.^[8] By contrast, the skull length of Albertoceratops was more typical for this group at only 67 cm.^[4] In general, centrosaurines were about the size of a rhinoceros with body lengths ranging from 2.5 to 8 meters.^[10]

Reproduction

Hypothesised ontogenic development of Pachyrhinosaurus perotorum

Possible neonate sized centrosaurine fossils have been documented in the scientific literature.^[11] Research indicates that centrosaurines did not achieve fully developed mating signals until nearly fully grown.^[12][3] Scott D. Sampson finds commonality between the slow growth of mating signals in centrosaurines and the extended adolescence of animals whose social structures are ranked hierarchies founded on age-related differences.^[12] In these sorts of groups young males are typically sexually mature for several years before actually beginning to breed, when their mating signals are most fully developed.^[13] Females, by contrast do not have such an extended adolescence.^[13]

See also

• Timeline of ceratopsian research

Footnotes

References

• Sampson, S. D. (1995b). "Two new horned dinosaurs from the Upper Cretaceous Two Medicine Formation of Montana; with a phylogenetic analysis of the Centrosaurinae (Ornithischia: Ceratopsidae)". Journal of Vertebrate Paleontology. 15 (4): 743–760. doi:10.1080/02724634.1995.10011259.
• Sampson, S. D., 2001, Speculations on the socioecology of Ceratopsid dinosaurs (Orinthischia: Neoceratopsia): In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 263–276.
• Tanke, D.H. and Brett-Surman, M.K. 2001. Evidence of Hatchling and Nestling-Size Hadrosaurs (Reptilia:Ornithischia) from Dinosaur Provincial Park (Dinosaur Park Formation: Campanian), Alberta, Canada. pp. 206–218. In: Mesozoic Vertebrate Life—New Research Inspired by the Paleontology of Philip J. Currie. Edited by D.H. Tanke and K. Carpenter. Indiana University Press: Bloomington. xviii + 577 pp.