SOUSA, BRAZIL—According to a Newsweek report, petroglyphs created between 3,000 and 9,000 years ago in eastern Brazil at the Serrote do Letreiro may have been inspired by the presence of preserved dinosaur footprints in the area. The footprints, made by ornithopod, theropod, and sauropod dinosaurs, are about 140 million years old. Leonardo P. Troiano of Brazil’s National Historic and Artistic Heritage Institute and his colleagues suggest that ancient artists may have used hallucinogens while creating the petroglyphs, many of which have been found next to the dinosaur footprints. The images, Troiano explained, are similar to visions reported by modern people under the influence of such drugs. Read the original scholarly article about this research in Scientific Reports. To read more about prehistoric Brazil, go to "Dark Earth in the Amazon."