New insights on Hispanomys moralesi (Rodentia, Mammalia) and its use as biostratigraphical indicator

Abstract

Here, we describe new specimens of the cricetid Hispanomys moralesi López-Antoñanzas et al. 2010, found in Batallones 4 site, which belongs to Cerro de los Batallones assemblage (Upper Vallesian, Upper Miocene). Previously, metrical and morphological data of H. moralesi have been used to proof whether the different sites within the butte were filled simultaneously or there was a time span among them (López-Antoñanzas et al. in Zool J Linnean Soc 160(4):725–747, 2010). 129 isolated molars, nine lower jaws, ten maxilla fragments and four skull remains from Batallones 4 were identified as H. moralesi and were included in the study. Length and width data were also taken on the dental pieces. This information has been used to perform a biometrical and morphological study, in order to compare the specimens of Batallones 4 with the rest of sites within the butte and with other Hispanomys species. The evolutionary stage of the fossils from Batallones 4 indicates that they are slightly more modern than the specimens from Batallones 10, and also have more primitive features than the ones from Batallones 1, 3 and 5. This information support the hypothesis by López-Antoñanzas et al. (2010): the cavities were not filled synchronously, but one after the other, beginning with southerner side of the butte (Batallones 10) and progressing towards north, being Batallones3 the last one to fill and, consequently, the youngest locality. The results remark the potential use of H. moralesi as a tool which can be used as a biochronological indicator that help us to relatively date a set of fossil sites.