On November 1, 1993, scientists at the U.S. Geological Survey presented new evidence at a seminar held at the U.S. Geological Society that the cause of the extinction of dinosaurs 65 million years ago was the decline in oxygen content in the Earth's atmosphere, not the impact of asteroids or meteorites impacting the Earth. After a group of scientists at the U.S. Geological Survey led by Garry Randis analyzed the ancient gas bubbles that remained in the amber fossils, it was discovered that the dinosaur era, the atmospheric oxygen content reduced from 35% to 28% from the highest in 2 million to 3 million years. Landis said that although the current atmospheric content is only 21%, the dinosaur era oxygen content decreased 10 to 20 times fas