A new Pliocene xerine sciurid (Rodentia) from Kossom Bougoudi, Chad

Abstract

A very well preserved, incomplete, articulated skeleton with nearly complete skull and mandible of a terrestrial squirrel belonging to the genus Xerus was unearthed at the Pliocene site of Kossom Bougoudi in Chad. Xerus daamsi, sp. nov. is characterized by a narrow nasal associated with medium size. The phylogenetic position of the new species among African Sciuridae was determined using cladistic analysis of craniodental characters. It is most similar to extant Xerus rutilus and Xerus erythropus, currently found in Ethiopia and Chad, respectively. Cladistic analysis also supports the monophyly of the African members of the tribe Xerini, and a sister group relationship between X. daamsi and X. rutilus whose position within the Xerini is poorly supported. The North African genus Atlantoxerus is valid and distinct from Xerus, emphasizing the faunal differences between North African and sub-Saharan regions of the continent. The close affinities of Xerus daamsi with xerines which are currently living in northern savannas, more precisely in the Horn of Africa, suggests the presence of the Somali-Masai vegetation type in Chad by 5 Ma.