TOOTH MORPHOLOGY OF ECHIMYIDAE (RODENTIA, CAVIOMORPHA): HOMOLOGY ASSESSMENTS, FOSSILS AND EVOLUTION

CANDELA Y RASIA

Congreso; IV Congreso latinoamericano de Paleontología; 2011

Echimyidae constitute the most important radiation of caviomorphs in the Neotropical region, represented by 20 extant genera and several extinct taxa, many of them known nearly exclusively by dental remains. Although profuse information on molar morphology and systematic of the Echimyidae is available, dental evolution of the family is yet poorly understood, because of the controversial identification of the homologies of the crown structures among different echimyid groups, and outside these rodents into a caviomorph higher-level phylogenetic framework. In this work we inspect crown structures of extinct and living echimyids and evaluate alternative primary homology hypotheses for echimyid crown structures of deciduous teeth and lower molars, comparing them particularly with those of the erethizontids. We explore the testing of alternative primary hypotheses of lophid correspondences of Echimyidae in a phylogenetic context. Following a “dynamic” approach, we choose the “best” primary homology hypothesis and evaluate the evolutionary transformations of the characters analyzed. Obtained results point out that pentalophodonty is primitive condition for the dp4, and the derived condition for the lower molars in Echimyidae, trilophodonty in lower molars evolved independently at least three times during the evolutionary history of these rodents, and the tetralophodonty represents the plesiomorphic condition. The phylogenetic analysis of extinct and extant echimyids here evaluated produced results which were concordant with traditional proposals and early times of divergence of extant genera proposed by molecular data.