Constraining the time of extinction of the South American fox Dusicyon avus (Carnivora, Canidae) during the late Holocene

A mass extinction affected South America during the late Pleistocene and early Holocene, when megamammals and large mammals disappeared. Several carnivores became extinct, including the sabretooth (Smilodon), the short-faced bear (Arctotherium), and some large canids (i.e., Protocyon, Canis dirus). After this mass event, virtually no carnivores became extinct in South America. The only exception is the fox Dusicyon avus, a medium-sized canid (estimated body mass between 10 and 15 kg) with a more carnivorous diet than the living South American foxes (Lycalopex culpaeus). The last record of the species comes from middle-late Holocene archaeological sites in the Pampean Region (Argentina) and Patagonia (Argentina and Chile). During the late Pleistocene, D. avus had a wide distribution, which covered part of Uruguay, Argentina (Buenos Aires province) and southern Patagonia. Although some remains from late Holocene sites have been published, these remains are still lacking numerical dating to determine the approximate date of extinction of this fox. This paper presents several new records from the Pampean and Patagonia regions, and several taxon dates. The new records indicate that D. avus survived in the late Holocene at least until ≈ 3000 BP in the Isla Grande de Tierra del Fuego (Patagonia) and the continent. Since at this time humans were occupying most of the Pampas and Patagonia, a revision of the causes behind the extinction of this fox is needed.