A new specimen ofGuaibasaurus candelariensis(basal Saurischia) from the Late Triassic Caturrita Formation of southern Brazil

The comparison of the anatomy of a second incomplete skeleton of Guaibasaurus candelariensis to that of basal Saurischia suggests that the origin of the “Prosauropoda” was from unknown basal saurischians, after separating from theropods (except herrerasaurids). Guaibasaurus and Saturnalia are part of this early dichotomy, and they bear mixed characters-states of basal theropods and “prosauropods” type. The Late Triassic age of both Guaibasaurus and Saturnalia (the latter is older) predates the ‘dominance’ of basal sauropodomorphs as well as the appearance of the basal theropod Zupaysaurus, both recorded from the upper Los Colorados Formation of Argentina.