Dental shape variation of Neogene Pachyrukhinae (Mammalia, Notoungulata, Hegetotheriidae): systematics and evolutionary implications for the late Miocene Paedotherium species

CANDELA, ADRIANA M.; ERCOLI, MARCOS DARÍO; RAMÍREZ, MARIANO; RASIA, LUCIANO; CANDELA, ADRIANA M.; ERCOLI, MARCOS DARÍO; RAMÍREZ, MARIANO; RASIA, LUCIANO

JOURNAL OF SYSTEMATIC PALAEONTOLOGY

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2018 vol. 16 p. 1073 - 1095

1477-2019

Paedotherium was the last representative of the pachyrukhines (Notoungulata,Hegetotheriidae), a small rabbit- or caviomorph rodent-like lineage, with hypsodont andsimplified dentition. Contrary to the Pliocene Paedotherium species, the Miocene ones areless known, mainly represented by teeth remains. Concerning this genus, differentsystematic studies based on the same set of subtly variants traits of the cheek teeth arrivedto different proposals. With the aim of testing the validity and analyzing the morphologicalvariation of Paedotherium species, and assessing the definition and diagnostic value ofteeth traits, we performed a dual approach: a qualitative traditional study together withexploratory geometric morphometrics analyses of the upper and lower cheek teeth (both,partial and complete series). In addition, the cheek teeth shape configurations were used aslandmark characters, in combination with traditional characters, to perform a phylogeneticanalysis. We propose the validity of the late Miocene P. borrelloi Zetti, and the assignmentof northwestern (NW) Argentina representatives of Paedotherium to P. aff. minor.Paedotherium borrelloi is morphologically more similar and phylogenetically more closelyrelated to the Pliocene P. bonaerense than to other Paedotherium species. Our resultssuggest that during late Miocene it was already established the coexistence of twoPaedotherium lineages, whose main morphological differences would have persisted oreven intensified in their Pliocene representatives, supporting a more complex evolutionaryscenario than previously thought.