The bears of the European steppe : a review

Abstract

Bears exhibit marked evolution for Pleistocene Europe. Both lineages are thought to have arisen from etruscan bear U. etruscus in the Early Pleistocene, however their high degree of polymorphism has prevented the establishment of an accepted evolutionary scenario. Isotopic analysis and tooth morphology of fossil brown bear U. arctos suggests that it was an omnivorous opportunist. The deningeri bear U. deningeri represents the spelaean bear of the Middle Pleistocene, sharing certain morphological affinities with brown bear U. arctos (frontal bulge and face; occlusal surface of jugular teeth). Within U. deningeri, several subspecies have been distinguished as evolutionary stages leading to the speciation of the cave bear U. spelaeus, the typical spelaean bear of the Late Pleistocene, which dominates cave fossil deposits. The speloïd lineage might serve as a good chronological marker for Pleistocene stratigraphic levels. There are several morphologically distinct lineages within U. spelaeus “sensu lato”, of controversial taxonomic status. Herbivorous feeding habits for U. spelaeus “s.l.” have been inferred from morphology (tooth, skull, jaw), demographics, and stable isotope analysis. This dietary difference between brown bears and cave bears shows that ecological competition was probably limited between both types. Paleo-genetic studies suggest that cave bears gradually lowered their reproductive rate (between 52,800 and 27,800 y BP) which led to their extinction at the onset of the last glacial maximum. Climatic changes are the main suggested causes responsible for the extinction of U. spelaeus