Evolutionary, taxonomical, and ecological traits of the Late Neogene armadillo Macrochorobates Scillato-Yané (Xenarthra: Cingulata)

Abstract

Within armadillos, two clades are currently recognized: Chlamyphoridae and Dasypodidae. Major evolutionary processes of Chlamyphoridae are linked to the main environmental and climatic events that occurred in South America in the Cenozoic. More precisely, the Euphractinae reached a high diversity concomitant with the cooling period of the Late Miocene–Pliocene. One of the largest euphractines is Macrochorobates, which includes the species M. scalabrinii and M. chapalmalensis, differentiated by minor details on the osteoderms of the dorsal carapace. This genus had a wide distribution, with records in Late Miocene–Pliocene deposits of different regions of Argentina. Here we describe and compare new specimens of M. scalabrinii, which represent the most complete material known so far. Our comparative analysis strongly suggests that M. chapalmalensis represents a junior synonym of M. scalabrinii. This way, the biochron of M. scalabrinii would range from the Late Miocene to the Late Pliocene. Additionally, anatomical comparisons and cladistic analysis show that Macrochorobates and Macroeuphractus (another Late Neogene large euphractine) share some cranial characters, not observable in other armadillos; therefore, we propose that Macrochorobates scalabrinii could have had intermediate carnivorous diets between more generalist taxa such as Euphractus and the specialized carnivory proposed for Macroeuphractus.