Electronic segmentation methods reveal the preservation status and otherwise unobservable features of the Mladeč 1 cranium

Abstract

History The story of the recovery of the Upper Paleolithic Mladeč/Lautsch site (Moravia, Czech Republic) is reasonably well known (Szombathy, 1925; Svoboda, 2000; Oliva, 1989; Jelínek, 1983). In 1881 and in 1882, Joseph Szombathy, assistant at the k.u.k. Naturhistorisches Museum, Vienna, carried out the first systematic excavations in the Johann von und zu Liechtenstein cave, commissioned to do so by the Imperial Academy of Sciences (Szombathy, 1882). All the human fossils collected by Szombathy were handed over to the newly established Anthropologisch-ethnographische Abteilung of the k.u.k. Naturhistorisches Museum, Vienna (Szombathy, 1925). Included in this trove and still stored in this Abteilung was the almost complete cranium of a young adult (16±1 years of age) female (Wolpoff et al., this volume), inventoried as Mladeč 1. This specimen has recently been dated at 31 thousand 14C years BP (Wild et al., 2005). Many illustrations of the cranium show the left side, hiding the fact that a large part of the right parietal is missing: the specimen had been damaged during the discovery and removal phase in 1881 (Szombathy, 1925). This (false) impression introduces a difficulty when assessing the morphology and is further corroborated by the fact that the missing parietal parts have been reconstructed during Szombathy's directorship of the Anthropologische Abteilung of the Naturhistorisches Museum, Vienna (perhaps even by Szombathy himself) using gypsum. (Indeed, in his 1925 publication, Szombathy himself concedes of having been once mislead in one morphological assessment due to the right-hand side having been reconstructed.) After this reconstruction had been completed, the exterior of the cranium had been covered with a curing agent and perhaps painted with shellac, changing the color of the fossilized bone and making the color difference between the gypsum reconstruction and the rest less apparent (see Wolpoff et. al., this volume, chap. 8, Plate I). The same covering had been applied to layers of encrustations (brownish calcite - we henceforth call this sinter - and considerably thick whitish staligmatic material) adhering to the many parts of fossilized cranium, notably at the base (see chap. 8, Plate I, below right) and inside the nasal aperture (see chap. 8, Plate I, top left). In this paper, we present a suite of electronic segmentation and removal procedures. As these are applied solely to the CT-scan of the specimen, they are reversible, non-invasive and leave the (priceless) original intact and unaltered. The result of the electronic segmentation procedure permits us to present, for the first time, the isolated fossil with all later additions/reconstructions and the encrustations removed. Because the methodologies use a CT-scan, we can also apply them to the interior of the cranium. As a result, we also present the heretofore-unknown endocranial status of this specimen. The result of this segmentation process and electronic "cleaning" or "preparation" is a 3D data file, which has been used to produce images, with and without the encrustations (Plates I-IV) for comparison and assessment purposes. Because a considerable part of Mladeč 1 has been left encrusted, morphological assessment using the (original) museum specimen is fraught with risks. One outcome of the segmentation process presented here is therefore the opportunity to reappraise the morphological features present in Mladeč 1. Another is that a more detailed record of the restoration work (especially the gypsum reconstructions of the crushed parietals) and the taphonomy has become possible. A third is the possibility of determining the 3D-coordinates of landmarks covered with encrustations in the original specimen. © 2006 Springer-Verlag/Wien. All rights are reserved.