The endocranium of the theropod dinosaur Ceratosaurus studied with computer tomography

• Autorzy: Sanders R K , Smith D.K.
• Języki publikacji: EN

Abstrakty

EN

A well preserved specimen of the theropod Ceratosaurusfrom the Upper Jurassic Morrison Formation of western Colorado was recently described and given the name C. magnicornis. The systematics of the genus is outside the scope of the present study but, as a generally accepted basal tetanuran, the braincase was CT scanned to provide a description of the endocranium, inner ear, pneumatic, and venous sinus systems in a primitive member of this clade. Five major subregions of the theropod endocranium are distinguished for the purpose of simplifying cranial computed tomographic interpretation and to provide a systematic means of comparison to other endocrania. The skull morphology of Ceratosaurus influences the overall braincase morphology and the number and distribution of the major foramina. The low pontine angle and relatively unflexed braincase is considered a more primitive character. The orientation of the horizontal semicircular canal confirms a rather horizontal and unerect posture of the head and neck. As in birds, the narrower skull morphology of Ceratosaurusis associated with fewer cranial nerve foramina. Additionally, the maxillary dominated dentigerous upper jaw of Ceratosaurusis felt to share with the alligator a large rostrally directed maxillary division of the trigeminal nerve and a small ophthalmic branch. The upper bill of birds, being dominated by the premaxillary and lacking teeth, is innervated predominantly by the ophthalmic division of the trigeminal nerve. For this reason, avian−based cranial nerve reconstructions are felt to be inappropriate for basal theropods.Ceratosaurusskull pneumatization and possible evidence of olfactory conchal structures is on the other hand very avian in character. Based on computed tomography, Ceratosaurusis determined to have possessed a typical basal theropod endocranium and bipedal vestibular system similar to Allosaurus.

Słowa kluczowe

EN

cranial pneumatic system; Ceratosaurus; virtual rendering; paleoneurology; Theropoda; theropod dinosaur; computer tomography; dinosaur; endocranium; paleontology

• Wydawca: -
• Czasopismo: Acta Palaeontologica Polonica
• Rocznik: 2005
• Tom: 50
• Numer: 3
• Opis fizyczny: p.601-616,fig.,ref.

Twórcy

autor

Sanders R K

• University of Utah HSC, 50 North Medical Drive, 1A71, Salt Lake City, Utah 84132, USA

autor

Smith D.K.

Bibliografia

• Bang, B. and Wenzel, B. 1985. Nasal cavity and olfactory system. In: A. King and J. McLelland (eds.), Form and Function in Birds, 195–225. Academic Press. London.
• Britt, B.B. 1993. Pneumatic Postcranial Bones in Dinosaurs and Other Archosaurs. 383 pp. Unpublished Ph. D. thesis. University of Calgary, Calgary.
• Brochu, C.A. 2000. A digitally−rendered endocast for Tyrannosaurus rex. Journal of Vertebrate Paleontology 20: 1–6.
• Brochu, C.A. 2003. Osteology of Tyrannosaurus rex: Insight from a nearly complete skeleton and high−resolution computed tomographic analysis of the skull. Society of Vertebrate Paleontology Memoir 7: 1–138.
• Burda, D.J. 1969. Developmental aspects of intracranial arterial supply in the alligator brain. Journal of Comparative Neurology 135: 369–380
• Coria, R.A. and Currie, P.J. 2003. The braincase of Giganotosaurus carolinii (Dinosauria: Theropoda) from the Upper Cretaceous of Argentina. Journal of Vertebrate Paleontology 22: 802–811.
• Chiasson, R. 1962. Laboratory Anatomy of the Alligator. 56 pp. W.M.C. Brown Company Publishers, Dubuque, Iowa
• De Beer, G.R. 1947. How animals hold their heads. Proceedings of the Linnean Society of London 159: 175–139.
• Dujim, M. 1951. On the head posture in birds and its relation to some anatomical features. Proceedings of the Koninklijke Nederlandse Akademie Van Wetenschappen, Series C. Biological and Medical Sciences 54: 260–271.
• Erichsen, J.T., Hodos, W., Evinger, C., Bessette, B.B., and Phillips, S.J. 1989. Head orientation in pigeons: postural, locomotor and visual determinants. Brain Behavior Evolution 33: 268–27.
• Fitzgerald, T. 1969. Splanchnology. In: The Coturnix Quail Anatomy and Histology, 239–243. Iowa State University Press, Ames, Iowa.
• Gilmore, C.W. 1920. Osteology of the carnivorous Dinosauria in the United States National Museum, with special reference to Antrodemus (Allosaurus) and Ceratosaurus. Bulletin of the United States National Museum 110: 1–154.
• Holtz, T.R. 2004. Tyrannosauroidea. In: D.B. Weishampel, P. Dodson, and H. Osmólska (eds.), The Dinosauria (second edition), 111–136. University of California Press, Berkeley, California.
• Hopson, J.A. 1979. Paleoneurology. In: C. Gans, R.G. Northcutt, and P. Ulinski (eds.), Biology of the Reptilia, Vol. 9, 39–146. Academic Press, New York.
• Kuhne, R. and Lewis, B.1985. External and middle Ears. In: A. King and J. McLelland (eds.), Form and Function in Birds, Vol. 3, 227–271. Academic Press, London.
• Larsson, H. 2001. Endocranial anatomy of Carcharodontosaurus saharicus (Theropoda: Allosauroidea) and its implications for theropod brain evolution. In: D. Tanke and K. Carpenter (eds.), Mesozoic Vertebrate Life, 19–33. Indiana University Press, Indianapolis.
• Madsen, J. and Welles, S. 2000. Ceratosaurus (Dinosauria, Theropoda): A revised osteology. Utah Geological Survey Miscellaneous Publication 2: 1–80.
• Marsh, O. 1896. The dinosaurs of North America. Annual Report of the United States Geological Survey 16: 133–244.
• Rogers, S.W. 1998. Exploring dinosaur neuropaleobiology: viewpoint computed tomography scanning and analysis of an Allosaurus fragilis endocast. Neuron 21: 673–679.
• Rogers, S.W. 1999. Allosaurus, crocodiles, and birds: evolutionary clues from spiral computed tomography of an endocast. The Anatomical Record 257: 162–173.
• Schumacher, G. 1973. The Head muscles and hyolaryngeal skeleton. In: C. Gans and T. Parsons (eds.), Biology of the Reptilia, 109–199. Academic Press. London.
• Sipla, J., Georgi, J., and Forster, C. 2004. The semicircular canals of dinosaurs: tracking major transitions in locomotion. Journal of Vertebrate Paleontology 24: 113A.
• Smith, C.A. 1985. Inner ear. In: A.S. King and J. McLellan (eds.), Form and Function in Birds, 273–310. Academic Press, London.
• Watanabe, T. and Yasuda, M. 1970. Comparative and topographical anatomy of the fowl XXVI: Peripheral course of the trigeminal nerve. The Japanese Journal of Veterinary Science 32: 43–57.
• Wedel, M.J., Cifelli, R.L., and Sanders, R.K. 2000. Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. Acta Palaeontologica Polonica 45: 343–388.
• Wever, E.G. 1978. Chapter 24. Order Crocodilia: The crocodiles. In: The Reptile Ear: Its Structure and Function, 924–964. Princeton University Press, Princeton, New Jersey.
• Witmer, L.M. 1995. Homology of facial structures in extant archosaurs (birds and crocodilians), with special reference to paranasal pneumaticity and nasal conchae. Journal of Morphology 225: 269–327.
• Witmer, L.M. 1997a. The evolution of the antorbital cavity of archosaurs: A study in soft−tissue reconstruction in the fossil record with an analysis of the function of pneumaticity. Journal of Vertebrate Paleontology 17, Memoir 3: 1–73.
• Witmer, L.M. 1997b. Craniofacial air sinus systems. In: P.J. Currie and K. Padian (eds.), Encyclopedia of Dinosaurs, 151–159. Academic Press, New York.
• Zippel, K.C., Lillywhite, H.B., and Mladinich, C.R.J. 2003. Anatomy of the crocodilian spinal vein. Journal of Morphology. 258: 327–335.