Ecosystem Structure and Trophic Network in the Late Early Cretaceous Crato Biome

The fossil record is uninformative concerning the habits and lifestyles of extinct organisms. Living species are positioned within a trophic hierarchy, presumably extinct taxa were susceptible to the same kind of environmental pressures operating today. In the past, the organisms held similar behavioral and evolutionary dynamics, but the paleoecological investigations are limited by the incompleteness of the fossil record. So, the opportunities to exanimate the structure of ancient ecosystem are extremely rare. The Cretaceous Crato Formation, northeastern Brazil, offers one of these opportunities. Crato fossils provide essential evidence for understanding major issues regarding evolution and paleoecology of this ancient ecosystem. The Crato Fm. deposition took place under anoxic and hypersaline bottom water conditions, as evidenced by the virtually undisturbed lamination pattern, the occurrence of halite pseudomorphs and by the absence of a benthonic fauna. These particular paleoenvironmental conditions made it possible to preserve an exceptional fauna and flora with fine details and even labile tissues. The fossil fauna and flora of the Crato limestone are considered to be predominantly allochthonous. Despite the high-fidelity preservation, the fossils are remarkable for their concentrated abundance as well as for their diversity. Therefore, understanding the trophic hierarchy of these organisms has already provided many important insights into the Early Cretaceous low-latitude Crato biome.