Proteogenomic insights from a waterlogged medieval pelt from Tønsberg, Norway

Background: Waterlogged archaeological deposits can preserve skin- and fur-based artefacts that are otherwise rarely recovered, yet their taxonomic attribution and biochemical integrity are often uncertain and difficult to evaluate by morphology alone. Here, a remarkably preserved fragment of hair-bearing pelt recovered during a 2014 rescue excavation in the medieval urban core of Tønsberg (Norway) and attributed, on stratigraphic grounds, to the 12th–14th century CE (the underlying timber structure being radiocarbon-dated to CE 1166–1210) was investigated to clarify its biological origin and preservation state through an integrated analytical workflow. Results: Optical and scanning electron microscopy showed that the hair and skin tissues retained their overall structural integrity, while FT-IR spectroscopy confirmed preservation of the collagen matrix (amide I and II bands) and informed the post-excavation handling and storage of the find. Bottom-up proteomics (nanoLC–MS/MS, Orbitrap) narrowed species attribution to caprines, with peptide evidence favouring Ovis aries over Capra hircus and identification of sheep-specific marker peptides in the hair fraction. Independent ancient DNA analysis targeting a short mitochondrial COI fragment (mini-COI) and high-throughput sequencing confirmed 100 % identity with Ovis aries , with Capra sequences showing substantially lower similarity. Significance: By converging protein- and DNA-based evidence, this study provides a robust species identification for a rare medieval pelt finding and demonstrates the value of proteogenomic integration for perishable cultural heritage materials, supporting more reliable interpretation, documentation, and conservation of fragile organic artefacts recovered from wet contexts.