Dinosaurs evolved from more primitive reptiles in the aftermath of Earth's biggest mass-extinction event caused by extreme volcanism at the end of the Permian Period about 252 million years ago.

Unfortunately, the uppermost (youngest) rock layers in the Grand Canyon date back to the Permian period, before the time of the dinosaurs, meaning there are no dinosaur fossils preserved in the area.

The 10,000-mile march through fire that made dinosaurs possible First study to consider how ancient reptiles dispersed across the Earth after end-Permian mass extinction Date: June 13, 2025 ...