Evolution of Borsodia (arvicolidae, mammalia) in the villanyian and in the early biharian

Abstract

Borsodia Janossy and Meulen is a genus of rooted voles belonging to the Mimomys group. The genus was a common element of small mammal associations in the Late Pliocene and the beginning of the Early Pleistocene, that is in the Villanyian and the Early Biharian, a period of about 1.5 Ma. The species of Borsodia were widely distributed in a latitudinal steppic belt stretching from North China to Central Europe. One of most striking morphological trends in the dental evolution of Borsodia was progressing hypsodonty. The rate of hypsodonty increase in Borsodia was not constant. It increased in a way close to exponential, having a period of relatively low rise in the Early Villanyian and a period of accelerated rise in the Late Villanyian and the earliest Biharian. This is interpreted as a reflection of the growing aridization. Late species of Borsodia gave rise to several rootless lagurine species of the modern fauna in a smooth morphological transition.