Combing through museum collections. A “museomic” application of ZooMS

This article presents the application of Zooarchaeology by Mass Spectrometry (ZooMS) to osseous Longobard artifacts from the collection of the “Musei Reali di Torino” (MRT; Torino, Italy). Like most archaeological items made of worked bone/antler in museum collections, the raw material of such specimens is usually attributed to deer, often without accurate taxonomic attribution. Therefore, the main aim of the present investigation was to shed light on taxonomical aspects using biomolecular approaches. We first examined the collagen preservation of the artifacts, then we compared three sampling methods (invasive, eraser-based, and bag-based), and we evaluated the quality of the collagen fingerprint obtained. Overall, we found a good, albeit not optimal, biomolecular preservation status, even in heavily restored objects coming from the 19th-century collections. Out of 37 specimens analyzed through matrix-assisted laser desorption ionization–time of flight–mass spectrometry (MALDI-TOF-MS) and nanoHPLC-tandem MS, 31 yielded usable data. The results confirmed the widespread use of cervid as the osseous raw material for comb-making in Longobard times in Piedmont, but we also found that bovine bones (Bos but also other taxa belonging to family Bovidae, such as caprines) and equid bones were exploited—demonstrating opportunistic use of animal resources. As far as the method is concerned, the ZooMS peptide markers useful to distinguish between bovids and cervids (m/z 1580 vsm/z 1550) (Buckley et al., 2009) are more frequently detected when analyzing bone chips, that is, with the invasive sampling method, rather than collagen extracts obtained using non-invasive techniques. Nonetheless, the eraser method (eZooMS) seems to be a good trade-off between invasivity and quality of the information obtained: eZooMS sampling does not leave visible marks on the object and therefore can contribute to facilitating the routine application of biomolecular methods in the daily practice of museum conservation laboratories. Indeed, an important outcome of the present study has been the establishment of a close collaboration between museum and biomolecular specialists. Taken together, our results suggest that the Longobards had a preference towards locally available resources, although this work did not highlight a clear association between raw material (deer, cattle, and other bovids) and object typology (in the case of combs) or function, except for buttons. The overall information obtained by this study confirms the potential of biomolecular approaches for reconstructing the biography of museum objects with a long and complex life and demonstrates the value of zooarchaeological study of museum collections.