PALEVO 1631-0683 Elsevier S1631-0683(10)00074-6 10.1016/j.crpv.2010.07.006 Research article General palaeontology Applications of imaging methodologies to paleoanthropology: Beneficial results relating to the preservation, management and development of collections Applications des méthodes d’imagerie en paléoanthropologie : apports en termes de préservation, gestion et développement des collections Clément Gaël Geffard-Kuriyama Didier Balzeau Antoine abalzeau@mnhn.fr a Crevecoeur Isabelle b h Rougier Hélène c b Froment Alain d Gilissen Emmanuel e f Grimaud-Hervé Dominique a Mennecier Philippe g Semal Patrick h CNRS, UMR 7194, département de préhistoire du Muséum national d’histoire naturelle, musée de l’Homme, 17, place du Trocadéro, 75016 Paris, France Laboratoire d’anthropologie des populations du passé, UMR 5199 PACEA, université Bordeaux 1, Talence, France Department of Anthropology, California State University Northridge, 18111 Nordhoff St., Northridge, CA 91330-8244, USA UMR 208, IRD et département hommes, natures, sociétés du Muséum national d’histoire naturelle, musée de l’Homme, 17, place du Trocadéro, 75016 Paris, France Department of African Zoology, Royal Museum for Central Africa, 3080 Tervuren, Belgium Laboratory of Histology and Neuropathology, université Libre de Bruxelles, 1070 Brussels, Belgium Direction des collections du Muséum national d’histoire naturelle, musée de l’Homme, 17, place du Trocadéro, 75016 Paris, France Laboratory of Anthropology and Prehistory, Royal Belgian Institute of Natural Sciences, 29, Vautier street, 1000 Brussels, Belgium 9 6-7 S1631-0683(10)X0006-9 Imaging & 3D in palaeontology and palaeoanthropology 3D & imagerie en sciences paléontologiques et paléoanthropologiques 265 275 © 2010 Académie des sciences. Published by Elsevier B.V. All rights reserved. 2010 Académie des sciences Full (PDF)

The limited number of unearthed fossils and their accessibility are factors that hinder paleoanthropological studies. Original remains, but also osteological collections of extant specimens, have to be curated in optimal and adapted environments, and direct manipulation needs to be limited in order to preserve this irreplaceable patrimony. Imaging methodologies have recently provided ways for innovative advances in the preservation of these collections, as well as offering new perspectives to museographic displays and original scientific studies. Here, we describe recent examples of developments obtained from imaging methodologies and discuss methodological and ethical implications of these new “virtual” collections. Undeniably, “virtual anthropology” is an additional tool in our large set of analytical possibilities and for curators, with its specific constraints related to the particular nature of the analysed material. Finally, we suggest some possible guidelines for the optimisation of the preservation, management and development of collections while preserving their scientific exploitation.

Le nombre réduit de fossiles découverts et leur accessibilité sont deux facteurs limitants en paléoanthropologie. Les fossiles originaux et les collections ostéologiques de spécimens actuels doivent être conservés dans des environnements parfaitement adaptés et leur manipulation doit être restreinte pour préserver ce patrimoine irremplaçable. Les méthodes d’imagerie ont récemment permis des avancées innovantes pour la préservation de ces collections, mais ont aussi ouvert de nouvelles perspectives en termes de présentation muséographique et d’analyses scientifiques. Nous décrivons des exemples récents obtenus grâce aux méthodes d’imagerie et discutons des implications méthodologiques et éthiques de ces nouvelles collections « virtuelles ». Incontestablement, « l’anthropologie virtuelle » est un outil supplémentaire dans notre éventail de possibilités analytiques, mais aussi pour les conservateurs, avec des contraintes liées aux particularités du matériel étudié. Enfin, nous proposons des pistes pour l’optimisation de la préservation, la gestion et le développement des collections tout en favorisant leur exploitation scientifique.

 Methods, Interdisciplinarity, Collaborations, Internal anatomy, Fossils, Cultural heritage, Digitisation Méthodes, Interdisciplinarité, Collaborations, Morphologie interne, Fossiles, Héritage culturel, Digitalisation presented Written on invitation of the Editorial Board Introduction

Numerous well-known limitations compose the everyday life of paleoanthropologists. The limited number of unearthed fossils and their accessibility are two factors that hinder studies of specimens’ characteristics and comparative analyses. Moreover, specimens are disseminated all around the world and students and researchers working on restricted budgets may encounter difficulties to be involved in analyses including original specimens. Fossils are also fragile and their manipulation has to be restricted, which complicates their exhaustive observation, particularly of hidden internal structures. The role of curators is twofold: preserving unique fossil remains and osteological collections on the one hand, and facilitating their museographic and scientific valorisation on the other. This difficult conciliation can be conflict-provoking at times regarding paleoanthropological study requests.

Historically, the invention of new imaging methodologies has encouraged rapid applications to the study of fossil hominid remains. As an example, the discovery of X-rays by Roentgen dates back to 1895, and Gorjanović-Kramberger (1902) published the first study based on two-dimensional radiographs on the Krapina fossils (other early examples are Walkhoff, 1903 and Schoetensack, 1908). Computed-Tomography (CT) was developed in the early 1970s (e.g., Hounsfield, 1973 and Hounsfield, 1976) and its use in anthropological research began as early as in the next decade. Pioneer researchers (e.g., Jungers and Minns, 1979, Ruff and Leo, 1986, Tate and Cann, 1982, Wind, 1984 and Zonneveld and Wind, 1985) were attracted by the opportunity to get access to the hidden structures of fossils, in spite of the technical limits of earlier equipment, at least compared to the current potentialities. Since then, this remarkable technological enhancement has produced numerous and diverse applications (e.g., see Spoor et al., 2000a and Spoor et al., 2000b for a review of elementary concepts in applications of diagnostic radiology to paleoanthropology). CT has obviously been a tool for diagnosis of normal anatomy and pathology in medical sciences but it has also been applied to ancient human skeletal remains for researching taphonomic bone alteration and pathology, and for describing their morphology. This imaging methodology permits to register, preserve and share our cultural heritage and opens up new perspectives while giving access to previously unavailable internal morphological features (Fig. 1 and Fig. 2). It therefore considerably increases the range of available data for studying morphological variability and the evolution of fossil hominids. Some examples of applications in paleoanthropology include the study of the frontal sinuses and their relationship with the face (e.g., Prossinger, 2008 and Seidler et al., 1997), the morphology of the maxilla and its pneumatisation (e.g., Maureille and Bar, 1999, Rae and Koppe, 2000 and Zollikofer et al., 2008), the temporal bone pneumatisation (e.g., Balzeau and Radovčić, 2008), the bony labyrinth (e.g., Hublin et al., 1996 and Spoor et al., 2003; Fig. 2a, b), the auditory capacities (e.g., Martínez et al., 2004), teeth (e.g., Conroy, 1988 and Conroy et al., 1995), the cranial vault thickness and its internal composition (e.g., Balzeau and Rougier, 2010 and Weber and Kim, 1999), the endocranial morphology (e.g., Bruner and Manzi, 2008, Falk et al., 2005 and Rosas et al., 2008), the mandibular corpus (e.g., Daegling, 1989 and Zollikofer et al., 1998), some previously unavailable features to evaluate individual specimen's age (e.g., Coqueugniot et al., 2004) and pathological alterations (e.g., Bräuer et al., 2003, Gracia et al., 2009 and Lukaszek et al., 2010). Moreover, this methodology allows the reconstitution and reconstruction of partial and/or deformed skulls (e.g., Suwa et al., 2009 and Zollikofer, 2005), the virtual association of anatomical structures and of osteological chains to modelize biological mechanisms (e.g., Chapman et al., in press and Ponce de León et al., 2008; Fig. 2c, d, e), and prototypes can be obtained from the 3D reconstructions (e.g., Seidler et al., 1997 and Zur Nedden et al., 1994; Fig. 1c). Applications to studies of the infra-cranial skeleton are less frequent and most have concerned the structural characteristics of long bones based on analyses of 2D sections (e.g., Ruff et al., 1999). Studies of enamel thickness and of the internal structure of teeth have recently benefited from rapid advances in micro-CT (μCT) (e.g., Bayle et al., 2010, Braga et al., 2010, Macchiarelli et al., 2006, Olejniczak et al., 2008, Skinner et al., 2008 and Smith and Tafforeau, 2008). Finally, imaging methodologies are also becoming a common complementary tool for the description of fossil specimens at the time of their announcement (e.g., Berger et al., 2010).

Imaging methodologies have recently provided ways for innovative advances in the preservation of collections of fossil and osteological specimens as well as offered new perspectives to museographic displays and original scientific studies. Here, we present some examples of applications of imaging methodologies to “cultural heritage” and scientific purposes and we discuss the limits and constraints of this approach. We also describe recent examples of collaborative developments of shared databases obtained from imaging methodologies and we discuss methodological and ethical implications of these new “virtual” collections. Finally, we suggest some guidelines for the optimisation of the preservation, management and development of collections as well as their scientific exploitation.

 General considerations about anthropological collections

Original fossil remains, as well as osteological collections of extant specimens, have to be kept in an optimal environment in terms of light, humidity and temperature, and manipulations have to be limited in order to preserve this patrimony. Fossil specimens are rare, fragile and evidently unique and irreplaceable. This is also true for osteological collections, which constitute the comparative samples of paleoanthropological studies, and which represent a valuable material for the analysis and interpretation of traits variability in recent and large samples. When considering, for instance, the great ape osteological material of the Royal Museum for Central Africa in Tervuren (Belgium), it even comes to mind that the biodiversity present in museums may in the future outgrow the natural biodiversity encountered in the field (Gilissen, 2009). Similarly, collections of anatomically modern humans housed in institutions around the world constitute a record of humankind in all its spatial and chronological aspects, which largest part remains to be studied.

Curators face a dilemma that lies in dealing with two antagonist missions: preserving unique fossil remains and osteological material on one hand, and facilitating their museologic and scientific development on the other, whereas the repetitive use of collections may at times endanger the preservation of their integrity (e.g., Culotta, 2005, Orschiedt, 2008 and White and Toth, 1981). Moreover, museum collection management has entered a new era because of the increasing use of new methodologies. Geometric morphometrics and imaging facilities, among others, and the development of new tools (e.g., digitizers, surface or CT scanners, etc.) have indeed generated a growing demand for access to osteological collections. New analytical methods also provide useful information in various fields (e.g., dating, diet, growth, pathology, palaeogenetics…), but they require destructive sampling, i.e. definitive damage to collections (e.g., Hublin et al., 2008). Undoubtedly, the value of a collection depends on what the data collected from its specimens can contribute to the scientific accumulation of knowledge.

In this context, applications of imaging methodologies offer important new opportunities for the preservation and the development of collections. All the information concerning the dimensions and the morphology of specimens may be registered. Moreover, this pluridisciplinary approach allows “virtual” manipulations and modifications of specimens, which were not possible before. Based on imaging datasets, the different parts of an object may be individualised, moved, rotated, scaled, restored, deformed, completed… In this respect, imaging methodologies represent an important opportunity for anatomical studies. They allow the observation, description, and quantification of previously unavailable features and, at the same time, they offer new perspectives for the preservation of collections.

Imaging methodologies are reputed for their non-destructive nature. This is partly true as the technique itself does not require any invasive preparation of the specimens to be imaged. Nevertheless, it is necessary to manipulate the original objects to dispose them in the acquisition equipment and to take them back to their repository after the procedure. Any manipulation is risky, be it in the lab with portative CT equipment or when specimens have to travel to be scanned in a hospital, in another laboratory or at a synchrotron facility. Moreover, the effects of intensive (and repetitive) exposure of fossils and osteological specimens to X-rays have not been studied on a large scale yet (e.g., Horton et al., 2010).

For these reasons, the digitisation of collections should not be intensively repeated until major technical improvements are achieved and the role of curators is crucial in managing the preservation of collections, the digitisation of specimens and their study by the scientific community.

 Specific constraints of “virtual anthropology”

2D CT datasets and 3D reconstructions, when correctly used, allow the observation and quantification of information similar to that obtained directly from original fossils. Moreover, “virtual” objects are permanently available for study. Classic descriptions, metric analyses and approaches in geometric morphometrics can be generated from this data, while preserving the original specimens.

Nevertheless, paleoanthropologists eager for novelty have to be aware that application of these methods to their field of research has limits. Some are directly inherent to the methodology itself. For example, in the case of heavily mineralised specimens, the settings of the acquisition procedure can be modified to avoid or limit imaging artefacts like overflow and beam hardening (Spoor and Zonneveld, 1994), but it is not always possible to obtain precise images with information about the fossil's internal structures with a CT scanner. Partial volume averaging and limits in spatial resolution (Spoor and Zonneveld, 1995) are two other important limitations of slice-based imaging methodologies. In relation to these two constraints, the accuracy and the reproducibility of measurements and of the definition of landmarks coordinates on both 2D and 3D data were tested and validated (e.g., Coleman and Colbert, 2007, Richtsmeier et al., 1995 and Schoenemann et al., 2007). However, the influence of measurement error is rarely quantified and discussed in publications in the field of “virtual (paleo)anthropology” (or VA). Different sources of uncertainty are involved at each step of the complete procedure when imaging methodologies are exploited, from the acquisition of imaging datasets on the original specimen, through informatics treatments of the data, and to metric or landmark determination on the virtual 3D reconstruction.

At the time of data acquisition, it is imperative to restrict the field of acquisition to the anatomical structure to be studied (Badawi-Fayad et al., 2005). Moreover, slice thickness has to be of comparable size as, or smaller than, pixel size in order to optimise the definition of the dataset in 3D. Physical and technical limitations may prevent the acquisition of some objects because of their size; this is particularly true for industrial CT scanners that are devoted to very small objects. Moreover, high-resolution acquisitions implicate large datasets that cause difficulties for their storage and their informatics processing. Today, it is sometimes necessary to reduce the resolution of original datasets obtained from μ-CT scanners or Synchrotron facilities to be able to study them because of limitations in informatic calculation capacities. On another hand, it is important not to dramatically reduce the spatial resolution during 3D reconstruction when using smoothing, compression or reduction procedures. The objective is not to obtain a beautiful model but a precise one. Slice data are by nature an incomplete registration of the 3D morphology of the original specimen. Computer-calculation reconstructs the 3D model from “cubic” information (i.e. voxels; pixels are the slices components and slice thickness provides the 3rd coordinates). Global segmentation permits to easily and rapidly obtain a 3D reconstruction. However, this model does not necessarily have a definition corresponding to the original spatial resolution of the CT dataset and does not automatically reproduce exactly the morphology of the original specimen because of variations in density of the different elements composing the images. It would be interesting to test the variation and accuracy of models obtained with different automatic segmentation procedures, and using various algorithms and software. Furthermore, users may encounter difficulties in defining precise outlines with automatic procedures. It is necessary to use manual segmentation with as many different settings as necessary to accurately isolate the outlines of a structure, particularly when sediment or plaster are present, or when the different parts of a fossil are characterised by large variations of density. In previous studies, we used multiple threshold values as a function of the variation in the mineralisation of fossils’ different components (bone, matrix, plaster…) to obtain 3D models. This was done for the endocranial cavity of the Mojokerto calvaria that is filled with sediment (Balzeau et al., 2005) and for virtually “cleaning” models of the Spy Neandertal crania (Balzeau et al., in press) of all the non-osseous structures that were used to complete the specimens just after their discovery at the end of the 19th century (Fig. 1).

Measurement error cannot be inferior to the resolution of the data used to quantify measurements of a specimen, but we have to be aware that the error can be very large depending on the different factors described above. Resolution of the original imaging dataset, estimations during 3D reconstruction, difficulties in determining the position of the landmarks on a virtual model are additional sources of error to more classic ones like repeatability of the determination of landmarks, quantification of the analysed traits and validity of the analytical protocol. We recently developed a specific protocol to quantify endocranial petalias using CT data (Balzeau and Gilissen, 2010 and Balzeau et al., 2010). Datasets were obtained following the previous recommendations for acquisition and treatment procedures. Measurement error was defined as the variation of the traits used to quantify symmetry and which actually represent a small percentage of anatomical traits size. Measurement error was then tested on a large part of the analysed samples and at the various methodological steps by comparing different CT acquisitions, different 3D reconstructions and different landmark acquisitions for the same specimens. Measurement error was found to be small compared to the variation observed for the different analysed features and it was comparable to the definition of the CT datasets used to reconstruct 3D models of the endocranial cavities. This demonstrates the high potential of imaging methodologies for studying small size anatomical traits when used properly.

The highest available resolution is of course preferable for the acquisition of specimens, but it should be kept in mind that analytical protocols are not necessarily reliable and valid simply because high resolution datasets are recorded.

First, the classic uncertainty in the determination of anatomical landmarks has to be considered. It is very easy to visualise details of a structure on a 3D model thanks to magnification possibilities on computer screens, probably even easier than on original specimens. However, a type II or III landmark (e.g., Bookstein, 1991 and O’Higgins, 2000) is obtained by construction on the virtual model and the user has to determine its location with the inherent imprecision of such a procedure. Similarly, the junction of sutures, in the case of type I landmarks, is not a point of infinitely small size that can be perfectly localised.

Second, any analytical protocol has to consider the particularities of imaging data, such as those described above, and particularly when dealing with 2D slices. A slice defined as passing through a particular structure or a number of anatomical landmarks does not have a real anatomical significance and will not be repetitive between individuals, even less between species. Moreover, a slice cuts structures in different oblique orientations depending on the orientation of the slice and of the structure that was imaged. This limitation is particularly significant when quantifying the thickness of a structure on 2D slices, such as cranial vault thickness (see Balzeau, 2006, Balzeau, 2007 and Balzeau and Rougier, 2010 for examples of protocols overcoming this problem; see Spoor and Zonneveld, 1995 for a protocol to analyse semi-circular canals size; Fig. 2a).

Finally, other limitations of “virtual anthropology” are the restricted number of specimens concerned by the studies and the difficulties in getting access to imaging datasets. The small sizes of our samples have to be acknowledged when interpreting results in terms of individual characteristics and variation.

Studies of internal anatomical features with imaging methodologies should be built while keeping in mind all the aspects presented above about the different steps of VA. For this reason, it is important that anthropologists working with imaging data are aware of all the information concerning the data they study; this is particularly true for data that were passed on by another scientist, and for 3D models that were not reconstructed by the user himself (Kullmer, 2008). In this context, scientists need complementary knowledge and skills in anatomy, imaging methodologies and informatics as much software is necessary for the various applications in paleoanthropology.

 Formats and supports

From a technical viewpoint, the great variability existing in raw data format is problematic. The Digital Imaging and Communication in Medicine (DICOM) format is a standard that was originally defined within the field of medical sciences to homogenise data obtained from CT scanning imaging equipment. However, variation remains between manufacturers and dedicated software is not able to open all DICOM format data. μ-CT devices produce radiographs that are turned into 2D slices after a reconstruction step. Classically, slices obtained from a μ-CT scanner are in TIFF format. Imaging datasets have the great advantage to be informatics data, hence easy to transport and to share, but they represent a large amount of data. In the near future, μ-CT scanners, and more probably synchrotron equipments, will certainly allow the acquisition of imaging data for complete skulls and large infra-cranial bones at a resolution of 50 μm or even less. Such a dataset would be meaningful in terms of the recording and preservation of a specimen at high resolution; however, it would require excessively large capacities of storage, and it would be extremely time consuming. In any case, possibilities of access to synchrotron facilities are currently so restricted that it is impossible to image more than one (or two) specimens at a time. Finally, the question of the long-term existence of data is problematic regarding both the storage of information and informatics formats. A policy for long-term management of “virtual” databases will be necessary and should be developed in museums in the same way as it exists for ‘physical’ collections.

 Perspectives for “virtual” paleoanthropologists

In the future, progresses in data acquisition and informatics treatment will certainly facilitate applications of imaging methodologies to paleoanthropology and will allow studying additional anatomical features of fossil specimens. It will also certainly be possible to include more specimens in “virtual” analyses as data acquisition becomes easier and cheaper, at least if present practices for data management and sharing evolve in a positive and productive way. Potential developments will concern the analysis of minute traits thanks to higher resolution capacities of acquisition facilities and the study of highly mineralised specimens thanks to the higher ability of these equipments to discriminate fossilised structures. Other possibilities will concern the reconstruction of fragmented fossils and the reversal of post-mortem deformations (Gunz et al., 2009), and advanced morphometric approaches based on large amounts of landmarks, surface and volume data.

 Perspectives for “virtual” curators

2D slices, CT derived or surface scanning 3D virtual reconstructions (e.g., Slizewski and Semal, 2009) and their derived prototypes are only partial images of the original objects, and their visualisation and analysis encounter specific constraints. Therefore, paleoanthropologists still have to study the original fossils to have a total understanding of the specimens. VA needs to be considered as an additional tool in our large set of analytical possibilities. For the institutions and museums represented by the curators, VA provides a “digital backup” of the specimens, it allows studies of taphonomic and/or curational processes and it provides useful information for the preservation and restoration of collections. For this reason, virtual models should be a part of the documentation associated to original collections in combination with pictures, drawings and metadata. This implicates the development of new expertise(s) related to the digitisation of original collections, not only for specific scientific questions but for a larger spectrum of applications.

 Ownership of “virtual” data

The question of ownership of “virtual” data deserves some attention. The simplest case is when the curator of the actual specimen is also responsible for the virtual data. It may occur that a specimen is imaged by a scientist with his own equipment or at his request. In this case, the scientist may consider that the virtual data are his property or he may request a period of exclusivity. This strategy is unproductive for the curator of the original specimen as well as for the scientific community. We should distinguish the importance and paternity of ideas and those of the specimens we study. Two principal levels of study of specimens are concerned by the applications of imaging methodologies. On one side, paleoanthropologists accomplish the exhaustive study of specimens and of their anatomy, either completing the study of ancient discoveries using new methodologies or describing recently unearthed and yet unpublished fossils. On the other side, applications concern the variation of anatomical traits among large samples to test general anthropological hypotheses. It is reasonably rational to preserve some mystery and discretion around analytical protocols and hypotheses to be tested before the publication of a paper or the accomplishment of a Ph.D. thesis. It is also undoubtedly natural that the discoverers of specimens be guaranteed the best conditions by curators to achieve the exhaustive study of their discoveries. Nevertheless, we should dismiss the longstanding idea that fossils and “digital fossils” are the unique property of their inventor, of their curator or of a scientist. A detailed policy should be established in order to manage this problematics.

During our own experience as “virtual paleoanthropologists”, we have had the opportunity to include specimens in our samples, which were unpublished or not yet fully published, because our work was not in conflict with the exhaustive studies of the fossils by their discoverers. The people in charge of these fossils gave us access to different sorts of data (CT, 3D model or landmark coordinates, depending on the protocol we used) for specific studies. In this context, we were able to analyse the variation of internal anatomical traits in hominins including large comparative series and important new specimens. In the same way, during the reassessment of the Spy collections by a pluridisciplinary team (Fig. 1 and Fig. 2), most of the 3D data sets produced were uploaded on the NESPOS and MARS databases and available to scientists on request.

 Ethical issues

Ethical issues are a complex aspect of VA. Rules for the use of imaging data and of the resulting images should be the same as for original specimens. The current policies concerning imaging data of fossils and osteological collections are highly variable between institutions according to various factors. Means in terms of staff, available budgets and collections are the three main elements that have permitted institutions to enter the “VA world” more or less rapidly. Institutions with paleoanthropologists interested in imaging methodologies and with funding resources have had opportunities to image their own collections or to contact other institutions to scan their specimens. Therefore, the scientific perspectives of applying imaging methodologies to paleoanthropology have been favoured first, and aspects of preservation and management of collections became a matter of interest only more recently. No one could have imagined the development of VA in terms of methodological improvement, multiplication of applications, quality of the results and number of scientists involved in such a short period of time. As a result, we have inherited a situation in which the management and control of the new “virtual” collections is ruled by variably well-defined conventions between scientists and institutions. Some problems arose and it is probably time for global, mutual and collaborative discussions and brainstorming. Following are some examples of situations that may emerge with the expansion of VA; they are marginal at the most, but they illustrate how complex the current situation is and why it would be useful to agree on some solutions.

STL files generated from imaging datasets permit one to obtain physical replicas of original specimens that may easily be used for commercial purposes. This issue is difficult to control, and it demonstrates the necessity of well-defined conventions at the time of imaging acquisition and before potential dissemination of the data. In some cases, a given scientist who generates a “virtual collection” may think that since he is the source of the collection, he may be its owner. This is a crucial point, and this situation might occur because CT scans, which are basically data, can easily be confused with the actual collections. When such an amalgam occurs, museums lose their intellectual property. This might happen when CT scans are shared by two or more scientists without leaving a copy at the museum where the scanned specimens are deposited; the museum (and funding agencies which covered the costs of the CT scanning) might not be acknowledged in publications using the CT data and they might be replaced by the owner of the CT scans. The same problem might occur with all of the information derived from original CT data, such as 3D models, and images of 2D slices and of 3D models. 3D reconstructions may indeed be shared by scientists without referring to the curators of the original specimens, and images obtained from CT data are occasionally published without reference to the institutions where the specimens are housed.

Finally, allowing a period of exclusivity to scientists who generated CT scans of specimens is problematic. When researchers scan specimens in institutions other than those that house the fossil material or with their own acquisition instrument, if the issue of intellectual property of the scans is not properly addressed, repeated scanning may occur and data may be unavailable for long periods of time. This raises issues about costs, repeated transport, repeated use, and repeated radiations, which consequences are naturally harmful to collections. Again, the role of curators is essential in combining the optimal conditions for the preservation of original specimens and for their scientific and museologic exploitation.

 Overview of “virtual” collections and of their policies

In this section, we want to present a few examples of anthropological “virtual” collections, which involve objectives in terms of both the preservation of collections and data sharing with the scientific community in prevision of new analyses. The earliest example of imaging datasets that were made widely available dates back to 1997 and concerns an osteological collection of extant modern humans (Shapiro and Richtsmeier, 1997). Data for fossil specimens have been made available to the scientific community starting in 1999 through the digital archives of fossil hominoids (Weber, 2001); CT scans of Kenyan fossil hominins are accessible through the National Museums of Kenya under individual license conditions. Another example is the Open Research Scan Archive (ORSA) database funded by the National Science Foundation and containing CT data of extant specimens (http://plum.museum.upenn.edu/∼orsa/). The basic policy of this experience is to encourage data exchange, which may be problematic for those who do not have “virtual” collections, but also when considering problems relating to data property as discussed above.

CT data of the specimens housed at the Museum national d’histoire naturelle (France) are disseminated to researchers for specific scientific purposes with the interdiction of sharing the data with a third party. Further analyses are only allowed after a new request is submitted in order to avoid conflicts in case of concurrent scientific approaches by different teams or scientists. Recently, some of us described and quantified the internal cranial features of RG 9338, the type specimen of Pan paniscus housed in the Royal Museum for Central Africa, Tervuren, Belgium, and most importantly, we provided a complete landmark description together with a 3D model (http://www.metafro.be/primates/panpaniscustype) in order to allow other scientists to include this key specimen in their own research (Balzeau et al., 2009a and Balzeau et al., 2009b). The original CT dataset is also available to scientists on request.

The largest project of 2D and 3D datasets repository in paleoanthropology is the NESPOS Society database (http://www.nespos.org) developed in the framework of ‘The Neanderthal Tools’ (TNT 2004–2006, a combined RTD- and demonstration project of the 6th framework program of the EU; see Semal et al., 2004b and Weniger et al., 2007). This project represents a major step in terms of collaborative and sharing developments of a web-based database for imaging datasets of fossil hominins, as well as of specific tools for anthropological and paleontological studies (i.e. the Visicore suite). The database is divided between public and private spaces. Registered users may download data on their local computer in order to use specific applications. Nevertheless, they are requested to mention the NESPOS origin of the data in the references of the publications using them. For the private spaces, sharing of data is established after a request is submitted and an agreement is found with the curator of the data. The NESPOS database offers a centralised solution for hosting 3D datasets. Curators are relieved of the hardware and technical infrastructure needed for housing digital collections, and they benefit from a common searching and sharing platform related to Pleistocene people and places.

The Royal Belgian Institute of Natural Sciences (RBINS) also developed a web database based on OpenSource technologies (Plone/Zope), which houses and allows the sharing of the digital collections of the institute, including all metadata related to original fossils. The MARS project (Multimedia Archeological Research System; Semal et al., 2004a), funded by the Belgian Science policy, hosts all CT, μCT and surface scanning files of the RBINS anthropological Pleistocene collections. This includes the Neandertal specimens from Spy, La Naulette and Fond-de-Forêt (Semal et al., 2005), and the Late Stone Age human remains from Ishango (Democratic Republic of Congo). To access these collections, a request has to be submitted to the curator and a user profile is then created on the MARS system.

This approach allows institutions to manage their own databases as a Multimedia CMS related to their collections. The use of a common portal like NESPOS, or other collaborative systems, redirects users to the server of each institution with their specific access rules and policy.

 Proposed guidelines for the benefit of collections

Through our various experiences, as scientists studying collections or dealing with particular anatomical traits, and/or as curators of fossil specimens and osteological collections, we have encountered the different difficulties discussed in this article about applications of imaging methodologies to paleoanthropology. This gave us the opportunity to think about possible guidelines for the preservation, management and development of collections while preserving their scientific exploitation.

 It is the role of curators to guarantee optimal conditions for the preservation of original specimens

Whenever possible, specimens should be documented using photography, high-resolution molding or prototyping, and surface and (μ)-CT scanning. This record of specimens is crucial in the perspective of possible repatriations of osteological elements, when invasive sampling is considered (e.g., Semal et al., 2009), or in the case of the loan and/or the exhibition of specimens, which are as many situations when the integrity of fossils may be threatened. Moreover, existing CT scans, surface data and 3D models should be made available at the request of visitors in order to limit manipulations of the original specimens for all the data acquisition that may be done as accurately on the “virtual” objects as on the originals. Finally, curators have to facilitate and to manage the scientific exploitation of the specimens in their care and of the corresponding “virtual” datasets.

 Imaging data obtained from specimens should remain the property of the institutions where the specimens are housed

A distinction should be made between raw data (original CT data, radiographs, TIFF files in the case of micro-CT data, photographs and surface views), which constitute a digital record of the specimens and are part of the collections, and segmented or reconstructed data (3D models produced from the various imaging methodologies, labels and segmented areas on slice-based data), which result from data processing and represent the work generated by the scientist him/herself. Nonetheless, any information derived from the original CT data, such as 3D models or images of 2D slices or of 3D models, should not be shared without referring to the curators of the original specimens.

Institutions and museums represented by the curators of fossil and/or osteological collections being also responsible for the management of the corresponding “virtual” raw data allows major benefits for the preservation and the exploitation of collections. Curators may grant several scientists or teams simultaneous access to the imaging datasets of specimens housed in their institution when it permits the achievement of complementary analyses and does not impede ongoing studies. When testing similar approaches or hypotheses, scientists should discuss potential conflicts of interest and redundancy of their analyses, and curators have to arbitrate in the best interest of the collection they are in charge of.

Finally, any scientific publication using fossil and/or osteological collections should systematically acknowledge the institutions which supplied the imaging datasets and where specimens are housed.

 Conclusions

In the near future, one of the major tasks concerning applications of imaging methodologies to paleoanthropology will be to conciliate the interests of the institutions and museums represented by the curators, who are in charge of the preservation and management of fossil and osteological collections, and of paleoanthropologists, who study the specimens. Imaging methodologies have provided ways for innovative advances in the preservation of collections as well as offered new perspectives for original scientific studies, which are sometimes conflicting. Ongoing and future developments of imaging methodologies, through the optimisation of acquisition equipments and of dedicated software, will certainly expand the possibilities of “virtual anthropology”. Methodological aspects of this pluridisciplinary approach should not be dismissed either. Scientists should be concerned with the optimal adaptations of acquisition and treatment protocols to the specific constraints of paleoanthropological remains and with the improvement of the repeatability and validity of their analytical procedures. Curators and scientists may find a common interest in developing a pedagogical approach for the public that they have more or less abandoned so far. Beautiful, colour images published in popular journals and flashy animations presented in congresses are now the rule, but we may also use the newly available opportunities for more advanced museographic displays. Finally, we hope that collaborative studies based on large samples of imaging datasets will be possible soon. This would provide more robust results and would certainly be beneficial for the preservation and the exploitation of collections. Fossils and osteological specimens compose the foundation of our research, and we should do all we can to preserve this heritage.

 Acknowledgments

We thank G. Clément and D. Geffard-Kuriyama for their invitation to contribute to this special issue, F. Détroit for his comments and discussions on the topics addressed in this paper, and L. Bouchneb and T. Chapman for their contribution to the illustrations. We are grateful to the institutions that funded the TNT (The Neanderthal Tools, IST 6th framework), the Spy Action 1 (Research project MO/36/012, Belgian Science Policy), and the MARS (IST project I2/2F/212, Belgian Science Policy) projects and the Ishango post-doctoral fellowship to I.C. (IRSIB, 2007-2009) that gave the opportunity to digitise the Pleistocene human remains of the RBINS. We also acknowledge the “Paul Broca II” project, 6th Framework Program of the European Community (contract number: 029023). The comments from two anonymous reviewers greatly improved this article.

 Badawi-Fayad J. Yazbeck C. Balzeau A. Nguyen T.H. Grimaud-Hervé D. Cabanis E.A. Multi-detector row CT scanning in Paleoanthropology at various tube current settings and scanning mode Surg. Radiol. Anat. 27 2005 536–543 Balzeau A. Are thickened cranial bones and equal participation of the three structural bone layers autapomorphic traits of Homo erectus? Bull. Mem. Soc. Anthrop. Paris 18 2006 145–163 Balzeau A. Variation and characteristics of the cranial vault thickness in Krapina and Western European Neandertals Period. Biol. 109 2007 369–377 Balzeau A. Gilissen E. Endocranial shape asymmetries in Pan paniscus, Pan troglodytes and Gorilla gorilla assessed via skull based landmark analysis J. Hum. Evol. 59 2010 54–69 Balzeau A. Radovčić J. Variation and modalities of growth and development of the temporal bone pneumatization in Neandertals J. Hum. Evol. 54 2008 546–567 Balzeau A. Rougier H. Is the suprainiac fossa a Neandertal autapomorphy? A complementary external and internal investigation J. Hum. Evol. 58 2010 1–22 Balzeau A. Gilissen E. Wendelen W. Coudyzer W. Internal cranial anatomy of the type specimen of Pan paniscus and available data for study J. Hum. Evol. 56 2009 205–208 Balzeau A. Gilissen E. Wendelen W. Coudyzer W. Erratum to Internal cranial anatomy of the type specimen of Pan paniscus and available data for study J. Hum. Evol. 57 2009 96–97 Balzeau, A., Grimaud-Hervé, D., Gilissen, E. 2010. Endocranial shape asymmetries in hominids, including fossil hominins and extant hominids, assessed via skull based landmark analysis of 3D reconstructions from CT images. Am. J. Phys. Anthropol. 141, S50, 60. Balzeau A Grimaud-Hervé D. Jacob T. Internal cranial features of the Mojokerto child fossil (East Java, Indonesia) J. Hum. Evol. 48 2005 535–553 Balzeau, A., Semal, P., Louryan, S., in press. CT reconstructions. In: Rougier, H., Semal, P. (Eds.), Spy Cave. State of 125 Years of Pluridisciplinary Research on the Betche-aux-Rotches from Spy (Jemeppe-sur-Sambre, Province of Namur, Belgium). Royal Belgian Institute of Natural Sciences and NESPOS Society, Brussels. Bayle P. Macchiarelli R. Trinkaus E. Duarte C. Mazurier A. Zilhão J. Dental maturational sequence and dental tissue proportions in the early Upper Paleolithic child from Abrigo de Lagar Velho Portugal Proc. Natl. Acad. Sci. U S A 107 2010 1338–1342 Berger L.R. de Ruyter D.J. Churchill S.E. Schmid P. Carlson K.J. Dirks P.H.G.M. Kibii J.B. Australopithecus sediba: a new species of Homo-like Australopith from South Africa Science 328 2010 195–204 Bookstein F.L. Morphometric tools for landmark data: geometry and biology 1991 Cambridge University Press Cambridge 456 p Braga J. Thackeray J.F. Subsol G. Kahn J.L. Maret D. Treil J. Beck A. The enamel-dentine junction in the post-canine dentition of Australopithecus africanus: intra-individual metameric and antimeric variation J. Anat. 216 2010 62–79 Bräuer G. Groden C. Delling G. Kupczik K. Mbua E. Schultz M. Pathological alterations in the archaic Homo sapiens cranium from Eliye Springs Kenya Am. J. Phys. Anthropol. 120 2003 200–204 Bruner E. Manzi G. Paleoneurology of an “early” Neandertal: endocranial size, shape, and features of Saccopastore 1 J. Hum. Evol. 54 2008 729–742 Chapman, T., Van Sint Jan, S., Moiseev, F., Louryan, S., Rooze, M., in press. From Modern Humans to Spy Ancestors? Comparison of the locomotion of anatomically modern humans and Neandertals (Spy II): a feasibility study. In: Rougier, H., Semal, P. (Eds.), Spy Cave. State of 125 Years of Pluridisciplinary Research on the Betche-aux-Rotches from Spy (Jemeppe-sur-Sambre, Province of Namur, Belgium). Royal Belgian Institute of Natural Sciences and NESPOS Society, Brussels. Chapman T. Moiseev F. Sholukha V. Louryan S. Rooze M. Semal P. Van Sint Jan S. Reconstruction of a Neandertal model by virtual modelling: with an example of application on the muscle moment arms of the hamstrings C. R. Palevol 2010 011 10.1016/j.crpv.2010.07.006 This issue Coleman M.N. Colbert M.W. Technical note: CT thresholding protocols for taking measurements on three-dimensional models Am. J. Phys. Anthropol. 133 2007 723–725 Conroy G.C. Alleged synapomorphy of the M1/I1 eruption pattern in robust australopithecines and Homo: evidence from high-resolution computed tomography Am. J. Phys. Anthropol. 75 1988 487–492 Conroy G.C. Lichtman J.W. Martin L.B. Some observations on enamel thickness and enamel prism packing in the Miocene hominoid Otavipithecus namibiensis Am. J. Phys. Anthropol. 98 1995 595–600 Coqueugniot H. Hublin J.J. Veillon F. Houët F. Jacob T. Early brain growth in Homo erectus and implications for cognitive ability Nature 431 2004 299–302 Culotta E. Discoverers charge damage to “hobbit” specimens Science 307 2005 1848 Daegling D. Biomechanicals of cross-sectional size and shape in the hominoid mandibular corpus Am. J. Phys. Anthropol. 80 1989 91–106 Falk D. Hildebot C. Smith K. Morwood M.J. Sutikna T. Brown P. Jatmiko Saptomo E.W. Brunsden B. Prior F. The brain of LB1. Homo floresiensis Science 308 2005 242–245 Gilissen E. Museum collections, scanning, and data access J. Anthropol. Sci. 87 2009 223–226 Gorjanović-Kramberger D. Der palaeolithische Mensch und seine Zeitgenossen aus dem Diluvium von Krapina in Kroatien Mitteilungen der Anthropologischen Gesellschaft Wien 32 1902 187–207 Gracia A. Arsuaga J.L. Martínez I. Lorenzo C. Carretero J.M. Bermúdez de Castro J.M. Carbonell E. Craniosynostosis in the Middle Pleistocene human cranium 14 from the Sima de los Huesos, Atapuerca Spain Proc. Natl. Acad. Sci. U S A 106 2009 6573–6578 Gunz P. Mitteroecker P. Neubauer S. Weber G.W. Bookstein F.L. Principles for the virtual reconstruction of hominin crania J. Hum. Evol. 57 2009 48–62 Horton C.F. Richards G.D. White T.D. MacDowell A. Jabbour R.S. Nasiatka J. Color centers induced in dental enamel during synchrotron microcomputed tomography: phase 1 assessment Am. J. Phys. Anthropol. S50 2010 131 Hounsfield G. Computerized transverse axial scanning (tomography) Br. J. Radiol. 46 1973 1016–1022 Hounsfield G. Picture quality of computed tomography Am. J. Roentgenol. 127 1976 3–9 Hublin J.J. Spoor F. Braun M. Zonneveld F. Condemi S. A late Neanderthal with Upper Palaeolithic artefacts Nature 381 1996 224–226 Hublin J.J. Pääbo S. Derevianko A.P. Doronichev V.B. Golovanova L.V. Friess M. Froment A. Hoffmann A. Kachache N.E.J. Kullmer O. Lordkipanidze D. Moncel M.H. Potts R. Radovic J. Rak Y.Z. Richards M. Méndez J.R. Rosas A. Schmauder M. Schmitz R.W. Semal P. Smith T. Tafuri M.A. Tattersall I. Tournepiche J.F. Toussaint M. Vassiliev S. Vialet A. White T. Ziegler R. Suggested guidelines for invasive sampling of hominid remains J. Hum. Evol. 55 2008 756–757 Jungers W.L. Minns R.J. Computed tomography and biomechanical analysis of fossil long bones Am. J. Phys. Anthropol. 50 1979 285–290 Kullmer O. Benefits and risks in virtual anthropology J. Anthropol. Sci. 86 2008 205–207 Lukaszek D.A. Irish J.D. Balzeau A. Froment A. Like I need a hole in the head: supernumerary external auditory meatus in a Carthaginian cranium Int. J. Osteoarchaeol. 20 2010 344–350 Macchiarelli R. Bondioli L. Debénath A. Mazurier A. Tournepiche J.F. Birch W. Dean M.C. How Neanderthal molar teeth grew Nature 444 2006 748–751 Martínez I. Rosa M. Arsuaga J.L. Jarabo P. Quam R. Lorenzo C. Gracia A. Carretero J.M. Bermúdez de Castro J.M. Carbonell E. Auditory capacities in Middle Pleistocene humans from the Sierra de Atapuerca in Spain Proc. Natl. Acad. Sci. U S A 27 2004 9976–9981 Maureille B. Bar D. The premaxilla in Neandertal and early modern children: ontogeny and morphology J. Hum. Evol. 37 1999 137–143 O’Higgins P. Quantitative approaches to the study of craniofacial growth and evolution: advances in morphometric techniques O’Higgins P. Cohn M. Development, growth and evolution. Implications for the study of the hominid skeleton 2000 Academic press London pp. 165–185 Olejniczak A.J. Tafforeau P. Feeney R.N.M. Martin L.B. Three-dimensional primate molar enamel thickness J. Hum. Evol. 54 2008 187–195 Orschiedt J. Der Fall Krapina – neue Ergebnisse zur Frage von Kannibalismus beim Neandertaler Quartär 55 2008 63–81 Ponce de León M.S. Golovanova L. Doronichev V. Romanova G. Akazawa T. Kondo O. Ishida H. Zollikofer C.P.E. Neanderthal brain size at birth provides insights into the evolution of human life history Proc. Natl. Acad. Sci. U S A 105 2008 13764–13768 Prossinger H. Mathematical analysis techniques of frontal sinus morphology, with emphasis on Homo Anat. Rec. 291 2008 1455–1478 Rae T.C. Koppe T. Isometric scaling of maxillary sinus volume in hominoids J. Hum. Evol. 38 2000 411–423 Richtsmeier J.T. Paik C.H. Elfert P.C. Cole T.M. III Dahlman H.R. Precision, repeatability, and validation of the localization of cranial landmarks using computed tomography scans Cleft Palate Craniofac. J. 32 1995 217–227 Rosas A. Peña A. Garcia-Tabernero A. Bastir M. De la Rasilla M. Fortea J. Endocranial occipito-temporal anatomy of the SD-1219 fossil from the El Sidrón Neandertals Anat. Rec. 291 2008 502–512 Ruff C.B. Leo F. Use of computed tomography in skeletal structure research Yearb. Phys. Anthrop. 29 1986 181–196 Ruff C.B. McHenry H.M. Thackeray J.F. Cross-sectional morphology of the SK 82 and 97 proximal femora Am. J. Phys. Anthropol. 109 1999 509–521 Schoenemann P.T. Gee J. Avants B. Holloway R.L. Monge J. Lewis J. Validation of plaster endocast morphology through 3D CT image analysis Am. J. Phys. Anthropol. 132 2007 183–192 Schoetensack O. Der Unterkiefer des Homo heidelbergensis aus den Sanden von Mauer bei Heidelberg 1908 Engelmann Leipzig Seidler H. Falk D. Stringer C. Wilfing H. Müller G.B. Zur Nedden D. Weber G.W. Recheis W. Arsuaga J.L. A comparative study of stereolithographically modelled skulls of Petralona and Broken Hill: implications for future studies of Middle Pleistocene hominid evolution J. Hum. Evol. 33 1997 691–703 Semal P. Cornelissen E. Nicolas N. MARS: Multimedia Archaeological Research System Notae Praehistoricae 24 2004 203–208 Semal P. Kirchner S. Macchiarelli R. Mayer P. Weniger G.C. TNT: the Neanderthal Tools Cain K. Chrysanthou Y. Niccolucci F. Pletinckx D. Silberman N. Interdisciplinarity or The Best of Both Worlds. The Grand Challenge for Cultural Heritage Informatics in the 21st Century. Selected papers from VAST2004 2004 pp. 43–44 Semal P. Toussaint M. Maureille B. Rougier H. Crevecoeur I. Balzeau A. Bouchneb L. Louryan St. De Clerck N. Rausin L. Numérisation des restes humains néandertaliens belges. Préservation patrimoniale et exploitation scientifique Notae Praehistoricae 25 2005 25–38 Semal P. Rougier H. Crevecoeur I. Jungels C. Flas D. Hauzeur A. Maureille B. Germonpré M. Bocherens H. Pirson S. Cammaert L. De Clerck N. Hambucken A. Higham T. Toussaint M. van der Plicht J. New data on the late Neandertals: direct dating of the Belgian Spy fossils Am. J. Phys. Anthropol. 138 2009 421–428 Shapiro D. Richtsmeier J.T. Brief communication: a sample of pediatric skulls available for study Am. J. Phys. Anthropol. 103 1997 415–416 Skinner M.M. Wood B.A. Boesch C. Olejniczak A.J. Rosas A. Smith T.M. Hublin J.J. Dental trait expression at the enamel-dentine junction of lower molars in extant and fossil hominoids J. Hum. Evol. 54 2008 173–186 Slizewski A. Semal P. Experiences with low and high cost 3D surface scanner Quartär 56 2009 131–138 Smith T.M. Tafforeau P. New visions of dental tissue research: tooth development, chemistry, and structure Evol. Anthrop. 17 2008 213–226 Spoor F. Zonneveld F. The bony labyrinth in Homo erectus: a preliminary report Cour. Forsch. Inst. Senckenberg 171 1994 251–256 Spoor F. Zonneveld F. Morphometry of the primate bony labyrinth: a new method based on high-resolution CT J. Anat. 186 1995 271–286 Spoor F. Jeffery N. Zonneveld F. Using diagnostic radiology in human evolutionary studies J. Anat. 197 2000 61–76 Spoor F. Jeffery N. Zonneveld F. Imaging skeletal growth and evolution O’Higgins P. Cohn M. Development, growth and evolution: implications for the study of the hominid skeleton 2000 Academic press London pp. 123–162 Spoor F. Hublin J.J. Braun M. Zonneveld F. The bony labyrinths of Neanderthals J. Hum. Evol. 44 2003 141–165 Suwa G. Asfaw B. Kono R.T. Kubo D. Lovejoy C.O. White T.D. The Ardipithecus ramidus skull and its implications for hominid origins Science 326 68 2009 pp. 68e1–68e7 Tate J.R. Cann C.E. High-resolution computed tomography for the comparative study of fossil and extant bone Am. J. Phys. Anthropol. 58 1982 67–73 Walkhoff O. Sechste Lieferung: die diluvialen menschlichen Kiefer Belgiens und ihre pithekoiden Eigenschaften Selenka E. Menschenaffen (Anthropomorphae), Studien über Entwickelung und Schädelbau 1903 C. W. Kreidel's Verlag Wiesbaden pp. 391–406 Weber G.W. Virtual Anthropology (VA): a call for glasnost in paleoanthropology Anat. Rec. 265 2001 193–201 Weber G.W. Kim J. Thickness distribution of the occipital bone: a new approach based on CT-data of modern humans and OH9 (Homo ergaster) Coll. Antropol. 23 1999 333–343 Weniger G.C. Döllner J. Macchiarelli R. Mandel M. Mayer P. Radovčić J. Semal P. The Neanderthal Tools and NESPOS. The World is in your eyes. Computer Applications in Archaeology 2005 Tomar 2007 267–269 White T.D. Toth N. Engis: preparation damage, not ancient cutmarks Am. J. Phys. Anthropol. 78 1981 361–367 Wind J. Computerized X-Ray tomography of fossil hominid skulls Am. J. Phys. Anthropol. 63 1984 265–282 Zollikofer C.P.E. Ponce de León M.S. Martin R.D. Computer-assisted Paleoanthropology Evol. Anthrop. 6 1998 41–54 Zollikofer C.P.E. Ponce de León M.S. Lieberman D.E. Guy F. Pilbeam D. Likius A. Mackaye H.T. Vignaud P. Brunet M. Virtual Cranial Reconstruction of Sahelanthropus tchadensis Nature 434 2005 755–759 Zollikofer C.P.E. Ponce de León M.S. Schmitz R.F. Stringer C.B. New insights into Mid-Late Pleistocene fossil hominin paranasal sinus morphology Anat. Rec. 291 2008 1506–1516 Zonneveld F. Wind J. High-resolution CT of fossil hominid skulls: a new method and some results Tobias P.V. Hominid revolution: past, present and future 1985 Alan R. Liss New York pp. 427–436 Zur Nedden D. Knapp R. Wicke K. Judmaier W. Murphy W.A. Seidler H. Platzer W. Study of a 5,300-year-old mummy: reproduction and investigation with CT-guided stereolithography Radiology 193 1994 269–272

The Spy 1 cranium; a: original specimen, from top to bottom: left lateral view, upper view and frontal view; b: CT images and 3D reconstruction; c: prototype obtained from the 3D reconstruction of the original specimen without all the non-osseous structures used to complete the specimen just after its discovery at the end of the 19th century (RBINS/TNT).

Crâne Spy 1 ; a : spécimen original, de haut en bas : en vue latérale gauche, en vue supérieure et en vue antérieure ; b : coupes CT et reconstruction 3D ; c : prototype obtenu à partir de la reconstruction 3D du spécimen original, sans les matières artificielles utilisées pour reconstituer le spécimen juste après sa découverte à la fin du xix e siècle (RBINS/TNT).

Examples of scientific analyses based on the CT data of the Neandertal remains from Spy (Belgium). a: left lateral view of the Spy 1 cranium with its in situ left bony labyrinth; b: right and left bony labyrinths of Spy 1 in lateral and upper views (images L. Bouchneb, RBINS/TNT); c: virtual models of the femur, tibia and calcaneus of Spy II and mirroring of the missing bones; d: the Spy II femur, tibia and fibula during a squat movement; e: the Spy II skeleton during a squat movement (published with kind permission of T. Chapman, ULB; see also Chapman et al., 2010, this issue).

Exemples d’analyses scientifiques à partir des données CT des vestiges néandertaliens de Spy (Belgique) ; a : vue latérale gauche du crâne Spy 1 et son labyrinthe osseux gauche représenté in situ ; b : labyrinthes osseux droit et gauche de Spy 1 en vues latérale et supérieure (images L. Bouchneb, RBINS/TNT) ; c : modèles virtuels des fémur, tibia et calcaneus de Spy II et symétrisation des ossements manquants ; d : fémur, tibia et fibula de Spy II durant un mouvement d’accroupissement ; e : squelette de Spy II pendant un mouvement d’accroupissement (publié avec l’aimable autorisation de T. Chapman, ULB ; se reporter à Chapman et al., 2010, ce volume).