The paleobiology of the extinct venomous shrew Beremendia (Soricidae, Insectivora, Mammalia) in relation to the geology and paleoenvironment of Dmanisi (Early Pleistocene, Georgia)

The uses of toxic substances in the animal kingdom are usually explained as adaptations to reach bigger preyvenom, or to defend from the attack of predatorspoison. This is a quite simplistic explanation of the reality, which offers other, less evident, uses for the possession of these compounds. In the present work, we analyze the characters of Beremendia Kormos, 1934, an extinct Eurasian genus of shrews, which was recently said to have been venomous. The envenomation apparatus of these shrews was correlated with its uncommonly large size, justifying a possible adaptation to hunt big prey. Examining its dental characters, we do reassess the venomous nature of the species included in this genus, but we deduce that the diet of Beremendia was highly specialized in coleopterans and gastropods instead of large animals. The use of venom in shrews feeding on non-struggling prey can be reliably explained as a mechanism to subdue the prey without killing them before the real time of consumption. The induction of victims into a comatose-state permits their hoarding for a longer time in a better state of preservation than if they were dead, thus diminishing the risk of starvation. Such strategy provides important benefits to their users under irregular conditions, because the effects of environmental unpredictability are consequently reduced. This interpretation of Beremendia is supported by the ethology of some extant shrews, and correlated at local scale with the geological context of Dmanisi, and at global scale with the Plio-Pleistocene climatic trends.