New remains of Eleutherocercus (Xenarthra, Cingulata, Glyptodontidae) from the Pampean and Northwestern regions of Argentina: morphology and phylogeny of late Neogene Doedicurinae

Abstract

The subfamily Doedicurinae is a monophyletic group of glyptodonts with their own anatomical features and is mostly known on the basis of the Pleistocene genus Doedicurus, one of the largest recorded taxa. The most distinctive character of the subfamily, unique within Cingulata, include the absence of ornamentation with large foramina, on the exposed surface of the carapace osteoderms. In terminal forms of the late Pleistocene, osteoderms have large foramina which tend to cross the entire thickness. The knowledge of the late Neogene diversity of the clade, as well as its evolutionary and geographical history, has increased in recent years, with important records in Argentina, where two late Miocene-Pliocene species are recognised: Eleutherocercus solidus from Catamarca and Tucumán provinces, and Eleutherocercus antiquus from Buenos Aires province. The most complete skull of E. antiquus from the early Pliocene Monte Hermoso Formation (ca. 5–4.2 Ma) is reported here. The specimen studied shows a conspicuous pathology on the parietal bones, first reported for fossil cingulates. In addition, the carapace of E. solidus is first described, on the basis of a partially complete specimen from the late Miocene-Pliocene (unknown stratigraphic level) from Tucumán province. Previous phylogenetic hypotheses of the relationships within the Doedicurinae, as well as their relationship with the remaining clades of Glyptodontidae, is tested in this study, adding new synapomorphies to the subfamily. The comparative study suggests that a third species previously proposed (E. paranaensis) from the ‘Mesopotamiense’ (late Miocene, Northeastern region of Argentina), must be considered as Eleutherocercus sp. Since their oldest record in the late Miocene, the latitudinal distribution of the Doedicurinae seems to have expanded rapidly reaching middle latitudes, particularly during the Pliocene, but during the Pleistocene (particularly the final lapse of this period), they began to retract latitudinally.