the volcanoes kicked into gear. Suddenly the diversity of non-dinosaur tracks drops dramatically in those first Jurassic rocks above the lava flows. Many non-dinosaur tracks abruptly disappear, including some of the most conspicuous prints left by crocodile-cousin pseudosuchians, which had previously been more abundant and diverse than the dinosaurs. Whereas dinosaurs made up only about 20 percent of all tracks before the volcanoes, right afterward half of all footprints belong to dinosaurs.
