Dental remains of Lower Miocene small rodents from Napak (Uganda): Afrocricetodontidae,Myophiomyidae, Kenyamyidae and Sciuridae

The Early Miocene sites of Napak (Uganda), which have been prospected by the Uganda Palaeontology Expedition since 1985, have yielded abundant fossil remains, including a rich and diverse rodent fauna. Ever since the work of Lavocat (1973) on the East African Miocene rodents, which focused mainly on the Kenyan remains (but included some material from Napak discovered by Bishop during the 1950s and 1960s), few studies have been made on the Ugandan specimens. This lack provides motivation for further study of Napak micro-mammals, especially the abundant rodents, which were collected at five sites, Napak IV, V, XV, XXX and XXXI. The fossils described here are attributed to six species representing four families: Afrocricetodontidae (Afrocricetodon songhori, Protarsomys macinnesi), Myophiomyidae (Myophiomys arambourgi), Kenyamyidae (Simonimys genovefae, Kenyamys mariae) and Sciuridae (Vulcanisciurus africanus). Comparison of the dentition of extant and extinct taxa allows us to propose dietary hypotheses (granivory, herbivory and omnivory) for these rodents. In addition, the fossil rodents associated with other fauna from the same localities suggest a more-or-less dense forest environment with clearings, and the probable presence of a humid climate at the time of deposition.