The morphological variation of fossil remains and the problematic notion of palaeontological species: the case of the Atlas bear resolved by ancient DNA analyses

Because of the morphological variation of the fossil remains, fossil species is a very difficult notion to define in palaeontology. This definition is effectively confronted to numerous problems such as body size polymorphism inside a natural population, co-existence of lineages with different morphotypes in a same species. Interestingly, paleogenetics can clarify such ambiguous situations. Size polymorphism and sexual dimorphism were particularly highly pronounced in Ursid populations. Taking as an illustration the extinct populations of brown bear in North Africa, we succeed in addressing the mitochondrial genetic diversity of these Atlas bears and the sexual dimorphism of these samples using molecular typing We are confident that these results will give useful information to palaeontologists in order to revisit the Atlas bears taxonomy and that this approach should be extended to other complex cases of palaeontological species.