Tooth morphology of Echimyidae (Rodentia, Caviomorpha): homology assessments, fossils, and evolution
Article first published online: 25 JAN 2012
© 2012 The Linnean Society of London
Zoological Journal of the Linnean Society
Volume 164, Issue 2, pages 451–480, February 2012
How to Cite
CANDELA, A. M. and RASIA, L. L. (2012), Tooth morphology of Echimyidae (Rodentia, Caviomorpha): homology assessments, fossils, and evolution. Zoological Journal of the Linnean Society, 164: 451–480. doi: 10.1111/j.1096-3642.2011.00762.x
- Issue published online: 25 JAN 2012
- Article first published online: 25 JAN 2012
- Received 10 September 2010; revised 11 May 2011; accepted for publication 17 May 2011
- Argentina – cheek teeth characters – dental evolution – Late Cenozoic – Myocastorinae – parsimony analysis
Echimyidae constitute the most important radiation of caviomorph rodents in the Neotropical region, represented by 20 extant genera and several extinct species. Both in extant and fossil forms, this diversity is reflected by a significant morphological variation found in crown structures of the cheek teeth. Different hypotheses of primary homology have been proposed for these structures, which, in turn, support diverse dental evolutionary hypotheses. In this contribution we inspect the main structures (cusps and lophids) of the lower deciduous teeth and molars in extinct and extant Echimyidae, and establish their topological correspondences. Comparisons with cusps and lophids of Erethizontidae are emphasized. We explore the testing of alternative primary hypotheses of lophid correspondences in a cladistic context. Following a ‘dynamic’ approach, we select the hypothesis of primary homology, which produced the more parsimonious results, and evaluate the evolutionary transformations of the dental characters analysed. In this context, the phylogenetic relationships of living Myocastor coypus (Molina, 1782) with the extinct Tramyocastor and Paramyocastor are tested. Our results indicate that pentalophodonty is the derived condition for the lower molars in Echimyidae, that trilophodonty evolved independently at least three times during the evolutionary history of these rodents, and that tetralophodonty represents the plesiomorphic condition. This study shows that dental evolution in echimyids can be better understood when occlusal structures are expressed as reliably comparable characters, and when fossils are taken into account.
© 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164, 451–480.