[5] After the discovery of numerous skeletons of the pterosaurs Caiuajara and Keresdrakon at the Cemitério dos Pterossauros site near Cruzeiro do Oeste, the remains of small theropods were uncovered between 2011 and 2015.

[5] The taxon is notable for its distinct, functionally monodactyl foot anatomy, where the singularly large third digit would have borne most of the weight while walking.

Based on the proportions of its holotype remains (MPCO.V 0065d), Vespersaurus was a small theropod with an estimated body length of 1–1.5 metres (3.3–4.9 ft).

The estimated body mass of Vespersaurus is 11.28 kilograms (24.9 lb), nearly that of the ornithischians Jeholosaurus shangyuanensis and Gasparinisaura cincosaltensis.

[10] However, Navarro et al. (2025) questioned the noasaurid interpretation for the trackmaker of Farlowichnus due to the difference in pedal and ungual anatomy compared to those of Vespersaurus.