Asynchronous ecological upheavals on the Western Mediterranean islands: New insights on the extinction of their autochthonous small mammals

Comparative studies on extinction scenarios are an invaluable contribution to enhance our understanding of their patterns and mechanisms underpinning them. This paper presents new radiocarbon dates based on specimens of five extinct mammal species from Mallorca and Sardinia. The new evidence permits to reanalyse the extinction dynamics on both islands. Radiocarbon ages directly obtained on bone collagen from these species show evidence of different extinction patterns on Mallorca and Sardinia. For Mallorca the most reliable scenario is a mass extinction of all non-volant mammal species as an immediate consequence of the first human irruption on the island. However, for Sardinia, the extinction of autochthonous mammals lasted over several millennia. The new radiocarbon dates of the last occurrence of endemic mammals suggest a sequence of punctuated extinction events throughout the late Sardinian Holocene. These events are here tentatively related to successive human colonisation waves. The current lack of chronological dates for some Sardinian fossil mammals impedes to outline a more accurate pattern of extinction events. The present paper points that Mallorca have been more vulnerable than Sardinia to the external disturbances introduced by humans. We suggest that the capacity of each island to absorb external perturbations could be related to the island area, the duration of the isolated evolution and the degree of faunal complexity.