Los mamíferos insulares del Mioceno medio y superior de Menorca (islas Baleares, Mediterráneo occidental)

Abstract

The insular mammals from the karstic deposits of Punta Nati-2 and the marine beds of es Cul de sa Ferrada, placed in the northwest coast of Minorca (Balearic islands, Spain, western Mediterranean) are described in this work. One of the mammals (only present in Punta Nati-2) is a new glirid species, Margaritamys adroveri, closely related with Margaritamys llulli Mein and Adrover, 1982 and Pseudodryomys granatensis Agustí, 1993, from the middle Miocene of Santa Margalida and Sant Llorenç (Mallorca) and Murchas (Granada), respectively. M. adroveri shows more derived characters than P. granatensis and is more archaic than M. llulli, the size being similar to P. granatensis. The ochotonid present in Minorca is very similar to Gymnesicolagus gelaberti Mein and Adrover, 1982 from Mallorca. In the two minorcan deposits were recovered the first mandibles of this ochotonid, characterized by their big size. The medium weight (estimated from the length of the lower row) for G. aff. gelaberti is 5.4 kg, very similar to that some extant leporids like Lepus alleni Mearns, 1890 or Lepus arcticus Ross, 1819 and higher than any other living ochotonid. Doubtless, the big size of G. aff . gelaberti is a consequence of insular evolution, but not the short diastema, a primitive character shared with continental ochotonids and insular leporids. The discovery of a mandible in the marine beds of es Cul de sa Ferrada permits to place G. aff. gelaberti in the lower Tortonian, which represents the youngest record for this species with respect the faunal associations of Mallorca and Granada, Langhian-Serravalian in age (middle-upper Miocene). The fauna from Punta Nati-2 may represent an endemic association or a faunal group closely related to the fauna of Mallorca and Granada, but in an older context. The age of Gymnesicolagus and the presence of a similar fauna in Mallorca and Minorca suggest a connection between both islands during the Serravalian and the existence of an emerged area in Minorca after the Tortonian transgression.