Scimitar-crested Spinosaurus species from the Sahara caps stepwise spinosaurid radiation

We describe a close relative of Spinosaurus aegyptiacus, the sail-backed, fish-eating giant from nearshore deposits of northern Africa. Spinosaurus mirabilis sp. nov., discovered in the central Sahara alongside long-necked dinosaurs in a riparian habitat, is distinguished by a scimitar-shaped bony crest projecting far above its skull roof. We discern three discrete phases in spinosaurid evolution. During the first phase with roots in the Jurassic, an elongate fish-snaring skull emerged that soon was modified along divergent paths. During a second Early Cretaceous phase, spinosaurids became the dominant predators in circum-Tethyan habitats. The final phase began just before the Late Cretaceous during the opening of the Atlantic Ocean, when spinosaurines attained maximum body size as shallow water ambush specialists limited geographically to northern Africa and South America.