The cranial osteology of Spermophilus richardsonii (Sabine, 1822) (Richardson's Ground Squirrel) (Mammalia : Rodentia : Sciuridae)

Much is known of the ecology and behaviour of Spermophilus richardsonii (Sa bine, 1822) (Richardson's Ground Squirrel), but little has been discussed o f its anatomy Here we document details of its cranial anatomy based upon 95 specimens from a single locality, focusing primarily on preciously undescr ibed features. This documentation provides the essential information for st udying intra- and interpopulational variation in cranial characteristics in both quantitative and qualitative contexts. Skulls of S. richardsonii exam ined were generally uniform in structure, and no obvious sexual differences were observed.