Bullar volume in subterranean and surface-dwelling caviomorph rodents

Abstract

Bullar volume was estimated by external measurements for the subterranean genus Ctenomys (Rodentia, Ctenomyidae) and 24 species of surface-dwelling caviomorphs. Bullae were larger in Ctenomys than in caviomorphs. Larger bullar size may reflect good low-frequency audition and could be an adaptation for subterranean vocal communication. Estimated bullar volume of the Pliocene rodent Actenomys was intermediate between that of Ctenomys and surface-dwelling caviomorphs, in agreement with the presumed intermediate subterranean lifestyle of Actenomys.