THE CHADRONIAN SQUIRREL SCIURUS-JEFFERSONI DOUGLASS, 1901 - A NEW GENERIC NAME, NEW MATERIAL, AND ITS BEARING ON THE EARLY EVOLUTION OF SCIURIDAE (RODENTIA)

A new genus, Douglassia, is erected for the problematic Chadronian sci urid Sciurus jeffersoni Douglass, 1901. Previously undescribed materia l adds new morphologic information for the taxon. Douglassia differs f rom other sciurids in the retention of primitive dental and masseteric morphology. Based on postcranial anatomy, the genus is referred to th e Tribe Sciurini (tree squirrels), which is regarded as the sister tax on to all other Sciurinae. The known fossil material of Tertiary flyin g squirrels is inadequate to determine whether they constitute a disti nct family.