New records of continental vertebrates from the Triassic of the Atacama Desert, northern Chile

Abstract

This contribution describes new vertebrate remains found in Triassic strata informally known as “Estratos El Bordo”, in the Atacama Desert, northern Chile. These include the first temnospondyl record in the El Bordo Basin, plus actinopterygians referable to the clade Pseudobeaconiidae and a second form with affinities to the incertae sedis ray-finned fish Guaymayenia paramillensis. Associated to these taxa, we describe two spiral coprolites. Their vertebrate producers are discussed. These new freshwater vertebrates add to previous archosaur records from “Estratos El Bordo”, represented by the putative aetosaur Chilenosuchus forttae, an indeterminate silesaurid and a fragmentary indeterminate Crocodylomorpha. Vertebrate remains here described show affinities to the known diversity from the Cuyana Basin of Argentina, but differ from those recorded in northern Argentina (Ischigualasto-Villa Unión Basin) and southern Brazil (Paraná Basin). This suggests preliminary paleoenvironmental insights for the continental vertebrates that inhabited the southwestern margin of South America during the Triassic. The new findings also support a Middle-to-Upper Triassic age for the “Estratos El Bordo” unit, as previously indicated by radioisotopic datating.