The last of its kind? Radiocarbon, ancient DNA and stable isotope evidence from a late cave bear (Ursus spelaeus ROSENMUELLER, 1794) from Rochedane (France)

摘要

We report here a new discovery of a cave bear left metatarsal 3 from Rochedane, an archaeological site near Montbeliard (French Jura) that yielded only Lateglacial and Holocene material, with no evidence of pre-LGM deposits, a context that made this bone a possible candidate for being a post-LGM cave bear in western Europe. To test this hypothesis, this bone was analyzed for mitochondrial DNA, which confirmed its attribution to cave bear of the Ursus spelaeus lineage, and a direct radiocarbon AMS dating on well preserved collagen (%C, %N and C/N well in the range of fresh collagen) yielded an age of 23,900 +110 -100 BP (28,730-28,500 cal BP, one sigma range). Its carbon and nitrogen isotopic values were similar to those of slightly older cave bears from the Swabian Jura, around 300 km to the East, suggesting that the ecological p of cave bears remained unchanged until the extirpation of this species in western Europe. Interestingly, the genetic type U. spelaeus was replaced by Ursus ingressus around 28,000 ~(14)C BP in the Swabian Jura. In contrast, the older type U. spelaeus apparently persisted in France ca. 3000 years longer. Traces left on the cave bear metapodium have been left by human activity on this bone, as it was the case for older cave bear bones from the Swabian Jura. This case study shows that cave bear remains found in post-LGM sites or layers may be candidates to be late survivors of this extinct species, but without direct radiocarbon AMS dated on well-preserved collagen (demonstrated by actual chemical composition results) and ancient DNA confirmation of the species attribution, such evidence can only be considered dubious.