Contents

A new species of Microdyromys, M. puntarronensis, is described from the Early Oligocene locality Mon-talbán 8 (Teruel, Spain). It is compared with the other Early Oligocene species of the genus, M. misonnei. The latter is known from Hoogbutsel (Belgium) and Montalbán 1D. Montalbán 8 is intermediate in age between Hoogbutsel and Montalbán 1D, and the dental pattern of its Microdyromys is more advanced than it is in Montalbán 1D. This leads to the conclusion that two lineages of Microdyromys existed in the Early Oligocene. An attempt is made to follow these lineages throughout the Late Oligocene and the Miocene