Unexpected Early Pliocene capybaras from the Mininco Formation and the first Neogene continental mammal record from the Chilean Central Depression

Abstract

This study reports the first record of Pliocene continental mammals from the Mininco Formation, located in the Central Depression of Chile, recovered during construction activities at the San Gabriel Wind Farm near the town of Renaico (37.7°S). The assemblage includes dental and postcranial elements attributable to the hydrochoerine rodent Phugatherium and to an indeterminate macraucheniid litoptern. These findings constitute the first anatomically supported evidence of capybaras in Chile and the first Neogene record of continental mammals from the Chilean Central Depression. The molar specimen exhibits diagnostic features of Phugatherium, including a prominent hypoflexus separating the tooth into two lobes, and shares notable similarities with P. novum. This discovery expands the known geographic distribution of hydrochoerines west of the Andes and suggests that the Renaico locality represented a heterogeneous landscape combining wetlands and open habitats. Additionally, it highlights the relevance of paleontological monitoring during infrastructure development in fossil-bearing regions. While further work is needed to fully understand the paleoenvironmental and biogeographic context, these remains demonstrate that the Mininco Formation holds valuable, though still understudied, potential for exploring the diversity and distribution of South American mammals during the Early Pliocene.