Small-sized mesotheriines (Mesotheriidae, Notoungulata) from northwestern Argentina: systematic, chronological, and paleobiogeographic implications

ARMELLA, M.; NASIF, N.; CERDEÑO, E

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2018 vol. 83 p. 14 - 26

0895-9811

TheNeogene outcrops in Northwestern Argentina have provided many fossil mammals,particularly notoungulates. However, the fossil record of the early stages ofthe late Miocene is scarce. The present study describes two mesotheriinespecimens from Las Arcas Formation (underlying the Chiquimil Formation dated at9.14 ± 0.09 Ma;Catamarca Province)and Saladillo Formation (dated at 10 ± 0.3 Ma; Tucumán Province), represented by a left maxillary fragment with complete M1?3 and a rightisolated M3, respectively. The main feature of these pieces is their smallsize, significantly smaller than that of the Miocene genera Eutypotherium, Typotheriopsis and Pseudotypotherium,recorded in Argentina. In contrast, these mesotheriines are closer to specimensknown from Bolivia. The comparative analysis allows us to refer the material hereindescribed to Plesiotypotherium aff. P. achirenseand Mesotheriinae indet., with all cautions inherent to the incompleteness ofthe material. In turn, the paleobiographic implication of these new records isapproached. A relationship concerning phylogenetic aspects, size, temporalrange, and distribution pattern is proposed, taking into account the small sizeof the studied material in a temporal context of medium to large-sizedmesotheriines.