Santana Group

The Santana Group is a geologic group in the Araripe Basin of northeastern Brazil, formerly classified as the middle part of the Araripe Group and now recognized as its own unit, comprising the Crato, Ipubi and Romualdo Formations. It dates to the Aptian through Albian stages of the Early Cretaceous, roughly 115 to 108 million years ago, and is made up primarily of mudstone, sandstone, shale and anhydrite, with secondary limestone, marl and siltstone, deposited in a lacustrine to subtidal shallow marine environment within the Araripe rift basin. The group spans three Brazilian states, Pernambuco, Piaui and Ceara, and its Crato and Romualdo Formations are both designated Lagerstatten, yielding an exceptionally rich assemblage of fossils, including flora, fish, arthropods, insects, turtles, snakes, dinosaurs such as Irritator, and pterosaurs such as Thalassodromeus, along with the first recorded Mesozoic birds found in Brazil. This entity documents the Santana Group specifically as a geological formation, an Early Cretaceous rift-basin sedimentary sequence renowned as a fossil Lagerstatte.