The rock carvings, which archaeologists call petroglyphs, are at a site called Serrote do Letreiro in Paraíba, an agricultural state on the eastern tip of Brazil. Researchers first observed the marks in 1975. But they are now interpreted as relating to the footprints following recent field surveys aided by drones, which uncovered previously unseen carvings. The tracks belong to dinosaurs from the Cretaceous Period, which ended 66 million years ago.