DENTAL SHAPE VARIATION OF NEOGENE PACHYRUKHINAE (MAMMALIA, NOTOUNGULATA, HEGETOTHERIIDAE): SYSTEMATICS AND EVOLUTIONARY IMPLICATIONS FOR THE LATE MIOCENE PAEDOTHERIUM SPECIES

RASIA, LUCIANO LUIS; RAMIREZ, M. A.; RAMIREZ, M. A.; ERCOLI, MARCOS D.; ERCOLI, MARCOS D.; CANDELA, ADRIANA MAGDALENA; CANDELA, ADRIANA MAGDALENA; RASIA, LUCIANO LUIS

JOURNAL OF SYSTEMATIC PALAEONTOLOGY

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2017

1477-2019

Paedotherium was the last representative of the pachyrukhines (Notoungulata,Hegetotheriidae), a small rabbit- or caviomorph rodent-like lineage, with hypsodont and simplified dentition. Contrary to the Pliocene Paedotherium species, the Miocene ones are less known, mainly represented by teeth remains. Concerning this genus, different systematic studies based on the same set of subtly variants traits of the cheek teeth arrived to different proposals. With the aim of testing the validity and analyzing the morphological variation of Paedotherium species, and assessing the definition and diagnostic value ofteeth traits, we performed a dual approach: a qualitative traditional study together with exploratory geometric morphometrics analyses of the upper and lower cheek teeth (both, partial and complete series). In addition, the cheek teeth shape configurations were used as landmark characters, in combination with traditional characters, to perform a phylogenetic analysis. We propose the validity of the late Miocene P. borrelloi Zetti, and the assignment of northwestern (NW) Argentina representatives of Paedotherium to P. aff. minor.Paedotherium borrelloi is morphologically more similar and phylogenetically more closely related to the Pliocene P. bonaerense than to other Paedotherium species. Our results suggest that during late Miocene it was already established the coexistence of two Paedotherium lineages, whose main morphological differences would have persisted or even intensified in their Pliocene representatives, supporting a more complex evolutionary scenario than previously thought.