The imagery on this page is the basis for a paper entitled Structural Extremes in a Cretaceous Dinosaur, by P.C. Sereno, J.A. Wilson, L.A. Witmer, J.A. Whitlock, A. Maga, O. Ide, and T.B. Rowe (PLoS ONE 2(11):e1230). The abstract is as follows:

       Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic.

This specimen, the left surangular, was collected from the Aptian-Albian horizons of the Tegama Group, Gadoufaoua region, Niger. It was made available for scanning by Dr. Paul Sereno of the University of Chicago. Funding for scanning and image processing was provided by Dr. Sereno. Additional funding for image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of the Department of Geological Sciences, The University of Texas at Austin.

The specimen was scanned by Matthew Colbert and Philip Watson on 1 February 2005 along the coronal axis for a total of 502 slices. Each 1024x1024 pixel slice is 0.2382 mm thick, with an interslice spacing of 0.2382 mm and a field of reconstruction of 104 mm.

Literature

Bakker, R.T. 1978. Dinosaur feeding behaviour and the origin of flowering plants. Nature 274:661-663.

Barrett, P.M., and Willis, K.J. 2001. Did dinosaurs invent flowers? Dinosaur–angiosperm coevolution revisited. Biological Reviews 76:411-447.

Calvo, J.O., and Salgado, L. 1995. Rebbachisaurus tessonei sp. nov., a new sauropod from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae. Gaia 11:13-33.

Dalla Vecchia, F.M. 2005. Between Gondwana and Laurasia: Cretaceous sauropods in an intraoceanic carbonate platform, pp. 395-429. In Carpenter, K., and Tidwell, V. (eds.), Thunder-lizards: The Sauropodomorph Dinosaurs. Indiana University Press, Bloomington.

Dalla Vecchia, F.M. 1998. Remains of Sauropoda (Reptilia, Saurischia) in the Lower Cretaceous (Upper Hauterivian/Lower Barremian) limestones of SW Istria (Croatia). Geologia Croatica 51/2:105-134.

Erickson, G.M. 1996. Incremental lines of von Ebner in dinosaurs and the assessment of tooth replacement rates using growth line counts. Proceedings of the National Academy of Sciences USA 93:14623-14627.

Evans, D.C. New evidence on brain-endocranial cavity relationships in ornithischian dinosaurs. Acta Palaeontologica Polonica 50:617-622.

Fiorillo, A.R. 1998. Dental microwear patterns from the sauropod dinosaurs Camarasaurus and Diplodocus: evidence for resource partitioning in the Late Jurassic of North America. Historical Biology 13:1-16.

Franzosa, J. W., and Rowe, T. 2005. Cranial endocast of the Cretaceous theropod dinosaur Acrocanthosaurus atokensis. Journal of Vertebrate Paleontology 25:859-864.

Gallina, A., and Apesteguía, S. 2005. Cathartesaura anaerobica gen. et sp. nov., a new rebbachisaurid (Dinosauria, Sauropoda) from the Huincul Formation (Upper Cretaceous), Río Negro, Argentina. Revista del Museo Argentino de Ciencias Naturales, nuevo serie 7:153-166.

Gheerbrant, E., and Rage, J.C. 2006. Paleobiogeography of Africa: how distinct from Gondwana and Laurasia? Palaeogeography, Palaeoclimatology, Palaeoecology 241:224-246.

Gradstein, F.M., Ogg, J.G., and Smith, A.G. (eds.). 2004. A Geologic Time Scale 2004. Cambridge University Press, Cambridge, pp. 589.

Hopson, J.A. 1979. Paleoneurology, pp. 39-146. In Gans, C. (ed.), Biology of the Reptilia Volume 9, Academic Press, London.

Janensch, W. 1929. Die Wirbelsäule der Gattung Dicraeosaurus. Palaeontographica (Suppl. 7) 2:39-133.

Kellner, A.W.A. 1996. Remarks on Brazilian dinosaurs. Memoirs of the Queensland Museum 39:611-626.

Krassilov, V.A. 1981. Changes of Mesozoic vegetation and the extinction of dinosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology 34:207-224.

Martin, J. 1987. Mobility and feeding of Cetiosaurus (Saurischia: Sauropoda) – why the long neck?, pp. 150-155. In Currie, P.J. and Koster, E.H. (eds), Fourth Symposium on Mesozoic Terrestrial Ecosystems, short papers. Tyrrell Museum of Palaeontology, Drumheller, Canada.

Naish, D., and Martill, D.M. 2001. Saurischian dinosaurs 1: sauropods, pp. 185-241. In Martill, D.M. and Naish, D. (eds.), Dinosaurs of the Isle of Wight. The Palaeontological Association, London.

Pereda-Suberbiola, X., Torcida, F., Izquierdo, L. A., Huerta, P., Montero, D. and Perez, G. 2003. First rebbachisaurid dinosaur (Sauropoda, Diplodocoidea) from the early Cretaceous of Spain: palaeobiogeographical implications. Bulletin de la Societe Geologique de France 174:471-479.

Rauhut, O.W.M., Remes, K., Fechner, R., Cladera, G., and Puerta, P. 2005. Discovery of a short-necked sauropod dinosaur from the Late Jurassic period of Patagonia. Nature 435:670-672.

Salgado, L., and Bonaparte, J.F. 1991. Un nuevo saurópodo Dicraeosauridae Amargasaurus caqaui gen. et sp. nov., de la Formación La Amarga, Neocomiano de la Provincia del Neuquén, Argentina. Ameghiniana 28:333-346.

Salgado, L., Garrido, A., Cocca, S.E., and Cocca, J.R. 2004. Lower Cretaceous rebbachisaurid sauropods from Cerro Aguada Del León, Neuquén Province, northwestern Patagonia, Argentina. Journal of Vertebrate Paleontology 24:903-912.

Schwarz, D., Frey, E., and Meyer, C.A. 2007. Pneumaticity and soft-tissue reconstructions in the neck of diplodocid and dicraeosaurid sauropods. Acta Palaeontologica Polonica 52:167-188.

Seebacher, F. 2001. A new method to calculate allometric length-mass relationships of dinosaurs. Journal of Vertebrate Paleontology 21:51-60.

Sereno, P.C., and Wilson, J.A. 2005. Structure and evolution of a sauropod tooth battery, pp. 157-177. In Rogers, K.C. and Wilson, J. (eds.), The Sauropods: Evolution and Paleobiology. University of California Press, Berkeley.

Sereno, P.C., Beck, A.L., Dutheil, D.B., Larsson, H.C.E, Lyon, G.H., Moussa, B., Sadleir, R.W., Sidor, C.A., Varricchio, D.J., Wilson, G.P., and Wilson, J.A. 1999. Cretaceous sauropods from the Sahara and the uneven rate of skeletal evolution among dinosaurs. Science 286:1342–1347.

Stevens, K.A., and Parrish, J.M. 2005. Digital reconstructions of sauropod dinosaurs and implications for feeding, pp. 178-200. In Rogers, K.C., and Wilson, J.A. (eds.), The Sauropods: Evolution and Paleobiology. University of California Press, Berkeley.

Upchurch, P., and Barrett, P.M. 2000. The evolution of sauropod feeding mechanisms, pp. 79-122. In Sues, H.-D. (ed.), Evolution of Herbivory in Terrestrial Vertebrates: Perspectives from the Fossil Record. Cambridge University Press, Cambridge.

Wilson, J.A., and Sereno, P.C. 1998. Early evolution and higher-level phylogeny of sauropod dinosaurs. Journal of Vertebrate Paleontology 18(2 SS):1-72.

Witmer, L.M. 2001. Nostril position in dinosaurs and other vertebrates and its significance for nasal function. Science 293:850-853.

Links

Nigersaurus on the Project Exploration website

The animations below were generated by Mr. Ryan Ridgely and Dr. Lawrence Witmer of Ohio University. Larger versions of the animations are available here.

Click on the thumbnail to the left for a yaw rotation animation (4.8 mb) of the reconstructed Nigersaurus skull model in natural alert posture.

Click on the thumbnail to the left for a yaw rotation animation (4.5 mb) of the reconstructed Nigersaurus skull model in intermediate posture.

Click on the thumbnail to the left for a roll rotation animation (2.9 mb) of the Nigersaurus brain and inner ear endocast.

Click on the thumbnail to the left for a yaw rotation animation (2.9 mb) of the Nigersaurus brain and inner ear endocast.

Click on the thumbnail to the left for a tumble rotation animation (2.7 mb) of the Nigersaurus brain and inner ear endocast.

Click on the thumbnail to the left for a rotation animation (6.1 mb) of the Nigersaurus maxilla rendered semi-transparent with tooth battery.

Click on the thumbnail to the left for a rotation animation (4.8 mb) of the Nigersaurus premaxilla rendered semi-transparent with tooth battery.