Paleobiogeographical significance of the Late Jurassic continental fauna from western Gondwana

The break-up of the western Gondwana paleocontinent during the earliest Late Jurassic in the southern hemisphere triggered several geological events associated with the opening of a seaway between the South American and African plates and this had long-term effects on regional biogeographic distribution. The pre-rift tectonic history of the northeastern Brazilian basins has proven crucial for understanding the faunal occurrences of the fossil remains scattered across South America, affecting the earlier paleobiogeographic aspects through vicariance and dispersal. The climatic crisis during the later Jurassic had an impact on the faunal distribution in western Gondwana. Consequently, the recent finds in some Brazilian localities and outcrops in Uruguay, Argentina and Chile have revealed close latitudinal similarities in their composition of continental fossil communities. The integration of two correlative environmental conditions associated with progressive early rift propagation potentially regulated the paleofaunal distribution. In the northeastern Brazil, the formation of mixed fluvial-aeolian borderlands with associated lakes indicates the presence of prevailing dry climates, whereas in the central to southern Brazil and northern Chile there are vast deposits of aeolian-dominated sandstone (Botucatu Formation) across a wide longitudinal range; this sequence is paleontologically documented solely by reptilian and mammalian fossil tracks. Such paleogeographic and paleoclimatic features are essential tools for understanding the circumstances of how fauna responded to prevailing harsh conditions and help explain the strong correlation between taxa in South America and Africa before the opening of the Atlantic Ocean.