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 dentary, 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 on 1 February 2005 along the coronal axis for a total of 956 slices. Each 1024x1024 pixel slice is 0.1297 mm thick, with an interslice spacing of 0.1297 mm and a field of reconstruction of 120 mm.

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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.