New Data on Carodnia feruglioi (Carodniidae, Xenungulata) from the Early Eocene of Patagonia (Argentina)

Abstract

The species Carodnia feruglioi and ‘Ctalecarodnia cabrerai' (Xenungulata) were originally described on scarce fragments of teeth from the current Peñas Coloradas Formation at Bajo Palangana (Chubut Province, Argentina). Based on them, the ‘Carodnia horizon’ was named containing one of the oldest native ungulates from South America. However, the type material of these enigmatic xenungulates has remained unknown for more than 80 years, and no updates were performed since their original descriptions. Here, the identification and re-study of the type material, as well as other unpublished specimens from several collections, allowed us to reconstruct part of the dentition of Carodnia feruglioi, describe previously-unknown teeth (e.g., incisors, lower canine, first and second lower molars, and upper molars) and introduce new dental characters for this species. Using length and width ratios of lower dentition (fourth lower premolar, second and third lower molars) as proxies, we compared the metric disparity among the Carodnia species. Based on this study, we provide an emended diagnosis for both the genus and species Carodnia feruglioi and establish comparisons among the six xenungulate documented.