Chaetophractus villosus (Desmarest, 1804) (Xenarthra: Euphractinae) in Uruguay (Upper Pleistocene): Taxon age, biogeography, and paleoclimatic implications

A skull of a fossil adult euphractine armadillo collected near San Ramon (Canelones department) is described. The specimen comes from the Lujanian deposits of the Dolores Formation (Upper Pleistocene-Greenlandian) in Uruguay. The skull is very similar to Chaetophractus villosus and Euphractus sexcinctus but is smaller and differs from the latter in having a well-separated optical foramen and sphenorbital fenestra. In E. sexcinctus, both foramina are placed nearer to one another in a single depression in the orbital region. The studied skull is larger, proportionally more slender and proportionally more depressed dorsoventrally compared with the skulls of Chaetophractus vellerosus and Chaetophractus nationi. Like E. sexcinctus, its ear canal is laterally located and differs from that of C. nationi and C. vellerosus, in which the canals are dorsally or dorsolaterally located, respectively. Finally, multivariate analyses support an affinity with Chaetophractus in terms of proportions. This finding, as well as its radiocarbon date, confirms the presence of C. villosus in Uruguay, extending its fossil record far outside the range of its current distribution. Furthermore, it suggests environmental conditions linked with a more arid and colder climate than that today in the southern part of Uruguay during the latest Pleistocene. This is congruent with the environmental information given by other representatives of the Dolores Formation fauna.

Automated summary

This article describes a fossilized skull of an extinct adult euphractine armadillo, which is smaller and has distinct differences compared to its living relatives. The finding confirms the presence of this species in Uruguay during the Late Pleistocene and suggests a colder and drier climate in the southern part of the country during that time period.