New insights about Hinasuri nehuensis (Aves, Rheidae, Palaeognathae) from the early Pliocene of Argentina

Abstract

Hinasuri nehuensis Tambussi was a robust, extinct rheid bird from the early Pliocene of Buenos Aires province, Argentina. This paper revisits the femoral morphology of H. nehuensis and provides an updated osteological description together with new insights into its palaeobiology. Size estimates and a comparison of standardized measurements relative to Rhea americana demonstrate that H. nehuensis had an above-average body mass. The femoral dimensions of H. nehuensis were also proportionately greater than those of R. americana, but its reconstructed musculature is otherwise very similar. This suggests that H. nehuensis had powerful proximal muscles consistent with its enlarged size. This could have been an advantage for avoiding predators and to tolerate the seasonally harsh environments of the Pampean region during the Pliocene–Pleistocene.