New remains of Glyptodontidae (Mammalia, Xenarthra) from the Salicas Formation (late Miocene, Messinian), La Rioja Province, Argentina

Abstract

In South America, glyptodonts are recorded since the late Eocene to the early Holocene. Their fossil record is represented mainly by disarticulated osteoderms during the Eocene and Oligocene, whereas more complete skeletons appeared since the early Miocene. The characters from the dorsal surface of the osteoderms (e.g., figures, foramina, sulci) are used for systematic recognition and phylogenetical relationships of Glyptodontidae. The aim of this contribution is to analyze a new collection of glyptodontid osteoderms from the Salicas Formation (late Miocene) at La Rioja Province, Argentina. The glyptodontids osteoderms herein presented are assigned to 1) Stromaphorus compressidens (CRILAR-Pv 113 and CRILAR-Pv 114) given the osteoderms have a central figure surrounded by a first row of 12–14 peripheral figures and, by a not always a complete second row of peripheral figures; and 2) Eosclerocalyptus cf. proximus (CRILAR-Pv 115) given the osteoderms have a circular to subelliptical central figure surrounded by a first row of 10 peripheral figures and by some peripheral figures located on a second row. The record of S. compressidens from Salicas Formation herein presented constitutes the first record of the species for the late Neogene of La Rioja Province; whereas the record of E. cf. proximus corroborates the presence of the genus in the Salicas Formation. The mammal assemblage recorded at the El Degolladito area suggests a latest Miocene age (Messinian) for the Salicas Formation at this locality.