HISTORY OF SOUTH AMERICAN OCTODONTOID RODENTS. ITS CONTRIBUTION TO EVOLUTIONARY GENERALISATIONS

VERZI, DIEGO HÉCTOR; MORGAN CC; OLIVARES, ADRIANA ITATÍ

Evolution of the Rodents: Advances in Phylogeny, Functional Morphology and Development

Cambridge University Press

Año: 2015; p. 139 - 163

South American Octodontoidea is the most species-rich clade among both extinct andextant hystricomorph rodents. The evolutionary histories of its two major groups,Octodontidae and Echimyidae, are differentially linked to the main Cenozoicpalaeoenviromental changes. According to a combined parsimony analysis ofmorphological and molecular data, they represent sister families, which were alreadyseparated in the late Oligocene, as well as the two major subclades comprised by eachone. Whereas the octodontid subclades Octodontinae and Ctenomyinae showprogressive stages of differentiation (modernisation) since the late Miocene, similarphases uncoupled from their respective origins are not recognizable in the echimyidsubclades. The greater spread of modern octodontids in the morphospace of skullvariation, and their greater relative disparity, independent of age and species richness,result from the abovementioned stages of differentiation and imply specialisation toopen environments. Thus, the history of octodontoids suggests that the acquisition ofevolutionary novelties is linked to the progressive emergence of new environments, andthis link is manifested through different hierarchies, i.e. geographic, temporal andanagenetic (amount of change, irrespective of cladogenetic events). For these rodents, aswell as for other terrestrial mammals, derived environments occur out of the tropics,thus highlighting the importance of extratropics as cradle of evolutionary novelties.