Restoration by other means: CT scanning and 3D computer modeling for the re-restoration of a previously restored skull from the Magdalenian Era

J. P. Brown and Robert D. Martin

Abstract

The Cap Blanc skeleton was discovered in France in 1911 by a workman who struck the skull at least once with a pickaxe while lowering the floor of the recently excavated rock shelter at Cap Blanc. The skeleton proved to be a Magdalenian era human and was subsequently acquired by the Field Museum in 1927. It was initially displayed with the fragmentary skull, but, in the early 1930s, the skull was reconstructed under the direction of Dr. Gerhardt von Bonin of the University of Illinois.

In 2012, we were able to use a mobile CT scanner to image the bones of the skeleton, including the skull. Upon examination of the scans, it became apparent that some features of the reconstruction of the cranium (sloped brow, small orbital cavities, and projecting nasal bones with large nasal opening) were anatomically incorrect, perhaps due to a self-consciously primitive restoration of the skull. We briefly considered reversing the 1930s reconstruction and using the original skull fragments to produce a more anatomically realistic reconstruction, but the importance of the specimen and the robust nature of the adhesive and gap-fill used in the 1930s reconstruction made the risk of damage while reversing the restoration unacceptably high. We, therefore, attempted to restore the skull to a more anatomically feasible state by converting the CT scan to a 3D software model showing each fragment in its current alignment, and then repositioning the fragments in software to produce a new reconstruction which could be viewed in software. We then 3D-printed the new reconstruction for further study.

In this paper we discuss the methods and software used for extracting and repositioning the fragments and the problem of arriving at a definitive reconstruction by this method. We include some commentary on 3D printing as a long-term preservation problem with consideration on the longevity of 3D-printed artwork. Finally, we review the result of our re-restoration of the skull.

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