A montage of the skulls of several crurotarsan archosaurs, the "crocodile-line" archosaurs that were the main competitors of dinosaurs during the Late Triassic period (230-200 million years ago). Top (l-r): The rauisuchians Batrachotomus and Postosuchus; middle: the phytosaur Nicrosaurus and the aetosaur Aetosaurus; bottom: the poposauroid Lotosaurus and the ornithosuchid Riojasuchus. Credit: Stephen Brusatte, Columbia University