Abstract
A previously undescribed chasmosaurine specimen excavated in 1919-1920 by William Cutler from the Dinosaur Park Formation of Alberta, Canada is referable to Chasmosaurus belli. The specimen comprises an almost complete skull in which, uniquely among Chasmosaurus, the cranial elements are disarticulated, allowing detailed examination of their morphology for the first time. The complete braincase is present and allows comparison with the braincase of other ceratopsians. The specimen also preserves an uncrushed and undistorted postcranium, including cervical, dorsal and sacral vertebrae and limb elements. The vertebral column of Chasmosaurus has never previously been described in detail, and NHMUK R4948 affords the opportunity to examine it because of the unparalleled state of vertebral preservation. A proliferation of new chasmosaurine genera has recently been described; many of them differ from each other only in details of frill and epiparietal morphology. Several of these are based on specimens previously referred to Chasmosaurus. As a result, the characters that distinguish Chasmosaurus from other Campanian chasmosaurines are unclear. However, the genus Chasmosaurus and species within the genus are diagnosable and valid based on unique combinations of characters and frill morphology. Detailed examination of the postcranial morphology of a variety of centrosaurines and chasmosaurines has highlighted previously undescribed synapomorphies for the two major ceratopsid clades, concentrated in the pectoral girdle and forelimb. Inconsistencies in the vertebral formula of specimens referred to Chasmosaurus belli suggests that the postcrania of ceratopsids may vary between species and genera far more than previously thought, and that postcranial characters should be incorporated into phylogenetic and taxonomic studies.References
Alexander, R.McN. (1991) How dinosaurs ran. Scientific American, 264, 62–68.
Bonnan, M.F. (2003) The evolution of manus shape in sauropod dinosaurs: implications for functional morphology, forelimb orientation, and phylogeny. Journal of Vertebrate Paleontology, 23, 595–613.
Brown, B. (1917) A complete skeleton of the horned dinosaur Monoclonius, and description of a second skeleton showing skin impressions. Bulletin of the American Museum of Natural History, 37, 281–306 +9 pl.
Brown, B. (1933) A new longhorned Belly River ceratopsian. American Museum Novitates, 669, 1–3.
Brown, B. & Schlaikjer, E.M. (1940) The structure and relationships of Protoceratops. Annals of the New York Academy of Sciences, 40, 133–266.
Butler, R.J., Upchurch, P. & Norman, D.B. (2008) The phylogeny of the ornithischian dinosaurs. Journal of Systematic Palaeontology, 6, 1–40.
Campione, N.E. & Holmes, R.B. (2006) The anatomy and homologies of the ceratopsid syncervical. Journal of Vertebrate Paleontology, 26, 1014–1017.
Chinnery, B.J. (2004) Morphometric analysis of evolutionary trends in the ceratopsian postcranial skeleton. Journal of Vertebrate Paleontology, 24, 591–609.
Chinnery, B.J. & Weishampel, D.B. (1998) Montanoceratops cerorhynchus (Dinosauria: Ceratopsia) and relationships among basal neoceratopsians. Journal of Vertebrate Paleontology, 18, 569–585.
Currie, P.J., Langston Jr., W. & Tanke, D.H. (2008) A new species of Pachyrhinosaurus (Dinosauria, Ceratopsidae) from the Upper Cretaceous of Alberta. In: Currie, P.J., Langston Jr., W. & Tanke, D.H. (Eds), A New Horned Dinosaur from an Upper Cretaceous Bone Bed in Alberta. NRC Research Press, Ottawa, pp. 1–108.
Dilkes, D.W. (2000) Appendicular myology of the hadrosaurian dinosaur Maiasaura peeblesorum from the Late Cretaceous (Campanian) of Montana. Transactions of the Royal Society of Edinburgh, Earth Sciences, 90, 87–125.
Dodson, P., Forster, C.A. & Sampson, S.D. (2004) Ceratopsidae. In: Weishampel, D.B., Dodson, P. & Osmólska, H. (Eds), The Dinosauria (2nd edition). University of California Press, Berkeley, pp. 494–516
Eberth, D.A., Brinkman, D.B. & Barkas, V. (2010) A centrosaurine mega–bonebed from the Upper Cretaceous of southern Alberta: implications for behaviour and death events. In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 495–508.
Erickson, B.R. (1966) Mounted skeleton of Triceratops prorsus in the Science Museum. Scientific Publications of the Science Museum, 1, 1–16.
Farke, A.A. (2006) Morphology and ontogeny of the cornual sinuses in chasmosaurine dinosaurs (Ornithischia: Ceratopsidae). Journal of Paleontology, 80, 780–785.
Farke, A.A. (2010) Evolution, homology, and function of the supracranial sinuses in ceratopsian dinosaurs. Journal of Vertebrate Paleontology, 30, 1486–1500.
Farke, A.A. (2011) Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U.S.A. PLoS ONE, 6, e16196. doi:10.1371/journal.pone.0016196.
Forster, C.A. (1996) New information on the skull of Triceratops. Journal of Vertebrate Paleontology, 16, 246–258.
Forster, C., Sereno, P.C., Evans, T.W. & Rowe, T. (1993) A complete skull of Chasmosaurus mariscalensis (Dinosauria: Ceratopsidae) from the Aguja Formation (Late Campanian) of west Texas. Journal of Vertebrate Paleontology, 13, 161–170.
Godfrey, S.J. & Holmes, R. (1995) Cranial morphology and systematics of Chasmosaurus (Dinosauria: Ceratopsidae) from the Upper Cretaceous of western Canada. Journal of Vertebrate Paleontology, 15, 726–742.
Goodwin, M.B., Clemens, W.A., Horner, J.R. & Padian, K. (2006) The smallest known Triceratops skull: new observations on ceratopsid cranial anatomy and ontogeny. Journal of Vertebrate Paleontology, 26, 103–112.
Hartwig, H.–G. (1993) The central nervous system of birds: a study of functional morphology. In: Farner, D.S., King, J.R. & Parkes, K.C. (Eds), Avian Biology: Volume IX. Academic Press, London, pp. 1–93.
Hatcher, J.B., Marsh, O.C. & Lull, R.S. (1907) The Ceratopsia. Monographs of the United States Geological Survey, 39, 1–295.
Hay, O.P. (1909) On the skull and the brain of Triceratops, with notes on the brain–cases of Iguanodon and Megalosaurus. Proceedings of the U.S. National Museum, 36, 95–108.
Holmes, R.B., Forster, C., Ryan, M.J. & Shepherd, K.M. (2001) A new species of Chasmosaurus (Dinosauria, Ceratopsia) from the Dinosaur Park Formation of southern Alberta. Canadian Journal of Earth Sciences, 38, 1423–1438.
Holmes, R.B., Ryan, M.J. & Murray, A.M. (2005) Photographic atlas of the postcranial skeleton of the type specimen of Styracosaurus albertensis with additional isolated cranial elements from Alberta. Syllogeus, 75, 1–75.
Hopson, J.A. (1979) Paleoneurology. In: Gans, C., Northcutt, R.G. & Ulinski, P. (Eds), Biology of the Reptilia:Volume 9. Academic Press, London, pp. 39–148.
Horner, J.R. & Goodwin, M.B. (2006) Major cranial changes during Triceratops ontogeny. Proceedings of the Royal Society B, 273, 2757–2761.
Irmis, R.B. (2007) Axial skeleton ontogeny in the Parasuchia (Archosauria: Psuedosuchia) and its implications for ontogenetic determination in archosaurs. Journal of Vertebrate Paleontology, 27, 350–361.
Ketchum, H.F. & Benson, R.B.J. (2010) Global interrelationships of Plesiosauria (Reptilia, Sauropterygia) and the pivotal role of taxon sampling in determining the outcome of phylogenetic analyses. Biological Reviews,85, 361–392.
Kirkland, J.I. & Deblieux, D.D. (2010) New basal centrosaurine ceratopsian skulls from the Wahweap Formation (Middle Campanian), Grand Staircase–Escalante National Monument, southern Utah. In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 117–140.
Lambe, L.M. (1902) New genera and species from the Belly River series (Mid–Cretaceous). Contributions to Canadian Palaeontology, 3, 25–81.
Lambe, L.M. (1914a) On Gryposaurus notabilis, a new genus and species of trachodont dinosaur from the Belly River Formation of Alberta, with a description of the skull of Chasmosaurus belli. The Ottawa Naturalist, 27, 145–154.
Lambe, L.M. (1914b) On the fore–limb of a carnivorous dinosaur from the Belly River Formation of Alberta, and a new genus of Ceratopsia from the same horizon, with remarks on the integument of some Cretaceous herbivorous dinosaurs. The Ottawa Naturalist, 27, 129–135.
Lambe, L.M. (1915) On Eoceratops canadensis, gen. nov., with remarks on other genera of Cretaceous horned dinosaurs. Canada Geological Survey Museum Bulletin, 12 (24), 1–50.
Lehman, T.M. (1989) Chasmosaurus mariscalensis, sp. nov., a new ceratopsian dinosaur from Texas. Journal of Vertebrate Paleontology, 9, 137–162.
Lehman, T.M. (1993) New data on the ceratopsian dinosaur Pentaceratops sternbergii Osborn from New Mexico. Journal of Paleontology, 67, 279–288.
Lehman, T.M. (1996) A horned dinosaur from the El Picacho Formation of west Texas, and review of ceratopsian dinosaurs from the American southwest. Journal of Paleontology, 70, 494–508.
Loewen, M.A., Sampson, S.D., Lund, E.K., Farke, A.A., Aguillón–Martínez, M.C., De Leon, C.A., Rodríguez–de la Rosa, R.A., Getty, M.A. & Eberth, D.A. (2010) Horned dinosaurs (Ornithischia: Ceratopsidae) from the Upper Cretaceous (Campanian) Cerro del Pueblo Formation, Coahuila, Mexico. In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 99–116.
Longrich, N.R. (2010) Mojoceratops perifania, a new chasmosaurine ceratopsid from the late Campanian of western Canada. Journal of Paleontology, 84, 681–694.
Longrich, N.R. (2011) Titanoceratops ouranous, a giant horned dinosaur from the Late Campanian of New Mexico. Cretaceous Research, 32, 264–276.
Lucas, S.G., Sullivan, R.M. & Hunt, A.P. (2006) Re–evaluation of Pentaceratops and Chasmosaurus (Ornithischia, Ceratopsidae) in the Upper Cretaceous of the Western Interior. New Mexico Museum of Natural History & Science Bulletin, 35, 367–370.
Lull, R.S. (1933) A revision of the Ceratopsia or horned dinosaurs. Memoirs of the Peabody Museum of Natural History, Yale University, 3, 1–173.
Maidment, S.C.R. & Porro, L.B. (2010) Homology of the palpebral and origin of supraorbital ossifications in ornithischian dinosaurs. Lethaia, 43, 95–111.
Maidment, S.C.R., Norman, D.B., Barrett, P.M. & Upchurch, P. (2008) Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia). Journal of Systematic Palaeontology, 6, 367–407.
Makovicky, P.J. (2001) A Montanoceratops cerorhynchus (Dinosauria: Ceratopsia) braincase from the Horseshoe Canyon Formation of Alberta. In: Tanke, D.H. and Carpenter, K. (Eds), Mesozoic Vertebrate Life. Indiana University Press, Bloomington, 243–262.
Mallon, J.C. & Holmes, R.B. (2006) A reevaluation of sexual dimorphism in the postcranium of the chasmosaurine ceratopsid Chasmosaurus belli (Dinosauria: Ornithischia). The Canadian Field–Naturalist, 120, 403–412.
Mallon, J.C. & Holmes, R.B. (2010) Description of a complete and fully articulated chasmosaurine postcranium previously assigned to Anchiceratops (Dinosauria: Ceratopsidae). In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 189–202.
Marsh, O.C. (1888) A new family of horned dinosaurs from the Cretaceous. American Journal of Science, series 3, 36, 477–478.
Maryańska, T. & Osmólska, H. (1975) Results of the Polish–Mongolian palaeontological expeditions – part 6: Protoceratopsidae (Dinosauria) of Asia. Palaeontologia Polonica, 33, 133–182.
Norman, D.B. (1986) On the anatomy of Iguanodon atherfieldensis (Ornithischia: Ornithopoda). Bulletin de l'Institut Royal des Sciences Naturelle de Belgique: Sciences de la Terre, 56, 281–372.
Ott, C.J. & Larson, P.L. (2010) A new, small ceratopsian dinosaur from the latest Cretaceous Hell Creek Formation, northwest South Dakota, United States: a preliminary description. In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 203–220.
Paul, G.S. & Christiansen, P. (2000) Forelimb posture in neoceratopsian dinosaurs: implications for gait and locomotion. Paleobiology, 26, 450–465.
Romer, A.S. (1956) Osteology of the Reptiles. Krieger Publishing Company, Malabar, Florida, 771 pp.
Rega, E., Holmes, R.B. & Tirabaso, A. (2010) Habitual locomotor behavior inferred from manual pathology in two Late Cretaceous chasmosaurine ceratopsid dinosaurs, Chasmosaurus irvinensis(CMN 41357) and Chasmosaurus belli (ROM 843). In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs. The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 340–354.
Ryan, M.J. & Evans, D.C. (2005) Ornithischian dinosaurs. In: Currie, P.J. & Koppelhus, E.B. (Eds), Dinosaur Provincial Park: A Spectacular Ecosystem Revealed. Indiana University Press, Bloomington, pp. 312–348.
Ryan, M.J., Russell, A.P., Eberth, D.A. & Currie, P.J. (2001) The taphonomy of a Centrosaurus (Ornithischia: Ceratopsidae) bone bed from the Dinosaur Park Formation (Upper Campanian), Alberta, Canada, with comments on cranial ontogeny. Palaios, 16, 482–506.
Ryan, M.J., Eberth, D.A., Brinkman, D.B., Currie, P.J. & Tanke, D.H. (2010) A new Pachyrhinosaurus–like ceratopsid from the upper Dinosaur Park Formation (Late Campanian) of southern Alberta, Canada. In: Ryan, M.J., Chinnery–Allgeier, B J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 141–155.
Sampson, S.D. & Witmer, L.M. (2007) Craniofacial anatomy of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. In: Sampson, S.D. & Krause, D.W. (Eds), Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. Society of Vertebrate Paleontology Memoir 8, pp. 32–98.
Sampson, S.D., Loewen, M.A., Farke, A.A., Roberts, E.M., Forster, C.A., Smith J.A. & Titus, A.L. (2010) New horned dinosaurs from Utah provide evidence for intracontinental dinosaur endemism. PLoS One, 5 (9), 1–12.
Sereno, P.C. (1986) Phylogeny of the bird–hipped dinosaurs (order Ornithischia). National Geographic Research, 2, 234–256.
Sereno, P.C. (1998) A rationale for phylogenetic definitions, with application to the higher–level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie–Abhandlungen, 210, 41–83.
Sereno, P.C. (1999) The evolution of the dinosaurs. Science, 284, 2137–2147.
Starck, D. (1979) Cranio–cerebral relations in recent reptiles. In: Gans, C. Northcutt, R.G. & Ulinski, P. (Eds), Biology of the Reptilia:Volume 9. Academic Press, London, pp. 1–38.
Sternberg, C.M. (1925) Integument of Chasmosaurus belli. The Canadian Field–Naturalist, 39, 108–110.
Sternberg, C.M. (1927) Horned dinosaur group in the National Museum of Canada. The Canadian Field–Naturalist, 41, 67–73. Sternberg, C.M. (1940). Ceratopsidae from Alberta. Journal of Paleontology, 14, 468–480.
Sullivan, R.M. & Lucas, S.G. (2010) A new chasmosaurine (Ceratopsidae, Dinosauria) from the Upper Cretaceous Ojo Alamo Formation (Naashoibito Member) San Juan Basin, New Mexico. In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 169–180.
Tanke, D.H. (2010) Lost in plain sight: discovery of William E. Cutler's lost Eoceratops. In: Ryan, M.J., Chinnery–Allgeier, B.J. & Eberth, D.A. (Eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington, pp. 541–550.
Tanke, D.H. & Farke, A.A. (2007) Bone resorption, bone lesions and extra cranial fenestrae in ceratopsid dinosaurs: a preliminary assessment. In: Carpenter, K. (Ed.), Horns and beaks: ceratopsian and ornithopod dinosaurs. Indiana University Press, Bloomington, pp. 319–347.
Thompson, S. & Holmes, R.B. (2007) Forelimb stance and step cycle in Chasmosaurus irvinensis (Dinosauria: Neoceratopsia). Palaeontologia Electronica, 10, 1–17.
Thompson, R.S., Parish, J.C., Maidment, S.C.R. & Barrett, P.M. (In press) Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora). Journal of Systematic Palaeontology.
Tsuihiji, T. (2010) Reconstructions of the axial muscle insertions in the occipital region of dinosaurs: evalutations of past hypotheses on Marginocephalia and Tyrannosauridae using the Extant Phylogenetic Bracket approach. The Anatomical Record, 293, 1360–1386.
Tsuihiji, T. & Makovicky, P.J. (2007) Homology of the neoceratopsian cervical bar elements. Journal of Paleontology, 81, 1132–1138.
Upchurch, P. (2009) The sauropod supermatrix: towards a global phylogeny of the largest terrestrial animals. Journal of Vertebrate Paleontology, 29 (3 suppl.), 194A.
Wiman, C. (1930) Über Ceratopsia aus der oberen kreide in New Mexico. Nova Acta Regiae Societatis Scientiarum Upsaliensis, series 4, 7, 1–19 +7 pl.
Witmer, L.M. & Ridgely, R.C. (2008) Structure of the brain cavity and inner ear of the centrosaurine ceratopsid dinosaur Pachyrhinosaurus based on CT scanning and 3D visualization. In: Currie, P.J. (Ed.), A New Horned Dinosaur From an Upper Cretaceous Bone Bed in Alberta. National Research Council Research Press, Ottawa, pp. 117–144.