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 ElBordo”, 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 incertaesedis ray-finned fish Guaymayenia paramillensis. Associated to these taxa, we describe two spiral coprolites. Theirvertebrate 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 afragmentary indeterminate Crocodylomorpha. Vertebrate remains here described show affinities to the knowndiversity from the Cuyana Basin of Argentina, but differ from those recorded in northern Argentina (Ischigualasto-Villa Union Basin) and southern Brazil (Parana Basin). This suggests preliminary paleoenvironmental insights for the continental vertebrates that inhabited the southwestern margin of South America during theTriassic. The new findings also support a Middle-to-Upper Triassic age for the “Estratos El Bordo” unit, as previously indicated by radioisotopic datating.