Vespersaurus

Vespersaurus paranaensis is a genus and species of small theropod dinosaur from the Late Cretaceous of Brazil. It is classified in Noasauridae, a family of ceratosaurs within Ceratosauria. The type material was recovered from the Paraná Basin in southeastern Brazil, a region associated with the Cretaceous Bauru Group. As a noasaurid, it is part of a lineage that diversified in Gondwana during the Cretaceous. The remains attributed to Vespersaurus are fragmentary, including hind limb elements and additional postcranial bones, and they indicate a fairly small, agile predator rather than a large apex hunter.

The name Vespersaurus combines vesper, Latin for evening, with sauros, Greek for lizard, reflecting its desert-like habitat and the arid landscapes of its environment. The specific epithet paranaensis refers to Paraná state. Estimates based on the available material suggest a small-bodied animal with limb proportions conducive to active terrestrial locomotion on open ground, consistent with other noasaurids. Given the fragmentary nature of the fossils, precise details of its skull and rest of the skeleton remain uncertain.

Paleoenvironments indicate a semiarid, dune-dominated ecosystem in the Late Cretaceous Paraná Basin. The discovery of Vespersaurus demonstrates the presence of noasaurids in southern South America and contributes to understanding the ecological breadth of Ceratosauria in Gondwana. It helps illuminate diversification patterns of small theropods in arid habitats during the dinosaurian history of the southern continents.