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Virtual cranial reconstruction of Sahelanthropus tchadensis

Abstract

Previous research in Chad at the Toros-Menalla 266 fossiliferous locality (about 7 million years old) uncovered a nearly complete cranium (TM 266-01-60-1), three mandibular fragments and several isolated teeth attributed to Sahelanthropus tchadensis1,2,3. Of this material, the cranium is especially important for testing hypotheses about the systematics and behavioural characteristics of this species, but is partly distorted from fracturing, displacement and plastic deformation. Here we present a detailed virtual reconstruction of the TM 266 cranium that corrects these distortions. The reconstruction confirms that S. tchadensis is a hominid and is not more closely related to the African great apes4,5. Analysis of the basicranium further indicates that S. tchadensis might have been an upright biped, suggesting that bipedalism was present in the earliest known hominids, and probably arose soon after the divergence of the chimpanzee and human lineages.

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Figure 1: State of preservation of the unreconstructed TM 266 cranium.
Figure 2: Virtual reconstruction of the TM 266 cranium (Frankfurt Horizontal plane orientation, orthographic projection).
Figure 3: TM 266 cranial reconstruction and comparative fossil hominid/African ape morphology.
Figure 4: Angular relationship between foramen magnum (FM) and orbital (OP) planes.

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Acknowledgements

We thank the Chadian Authorities (Ministère de l'Éducation Nationale de l'Enseignement Supérieur et de la Recherche, Université de N'Djaména, Centre National d'Appui à la Recherche au Tchad), the Ministère Français de l'Éducation Nationale (Faculté des Sciences, Université de Poitiers), Ministère de la Recherche (CNRS: Départment SDV & ECLIPSE), Ministère des Affaires Étrangères (DCSUR Commission des fouilles, Paris, et SCAC Ambassade de France à N'Djaména), the Revealing Hominid Origins Initiative (co-principal investigators F. C. Howell and T. D. White), the American School of Prehistoric Research, Harvard University, and the Swiss National Science Foundation, for support; the MultiMedia Laboratorium, University of Zürich (P. Stucki); EMPA Dübendorf, Switzerland, for industrial computed tomography (A. Flisch); all the MPFT members; and S. Riffaut, X. Valentin, G. Florent and C. Noël for technical support and administrative guidance.

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Correspondence to Michel Brunet.

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The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Table S1

Craniometric measurements of the virtual reconstruction of the TM 266-01-60-1 Sahelanthropus tchadensis cranium. (XLS 12 kb)

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Zollikofer, C., Ponce de León, M., Lieberman, D. et al. Virtual cranial reconstruction of Sahelanthropus tchadensis. Nature 434, 755–759 (2005). https://doi.org/10.1038/nature03397

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