For 800 years, St. Botolph's Church in Hadstock, UK had a pelt nailed to its front door that was thought to have once belonged to a Viking who tried to raid the church in the 11th century. The story is that he was caught, skinned alive, a large patch of his flesh was nailed to the door as a deterrent. Turns out these kinds of gruesome warnings have been seen in several other medieval churches in the region, including Westminster Abbey. The skin was removed from the doors long ago but the samples have been preserved, prompting Cambridge University researcher Ruairidh Macleod and colleagues to analyze it with a new mass spectrometry technique. Turns out that none of the four samples came from a human. From Ancient Origins:
Macleod and his colleagues analyzed the skin fragments from all four church doors using a non-destructive technique called "Zooarchaeology by Mass Spectrometry" or ZooMS. Notably, the technique has helped scientists pick a single Neanderthal bone from among 2,300 bone fragments belonging to animals like mammoths, woolly rhinos, wolves, and reindeer in Russia's Denisova Cave.
The technique reveals the collagen peptide sequence in bone fragments, allowing scientists to identify to which species a bone once belonged[…]
While the St Botolph's and Westminster Abbey ones came from bovines, the St Michael and All Angels Church skins belonged to a horse or donkey.