In the first 20 million years of the Cambrian period, Earth experienced an explosion of life—a great evolutionary era dubbed the Cambrian Explosion. However, as of now, the Cambrian explosion is still a benchmark for scientists probing the evolution of early life on Earth. There is also little to no evidence of complex digestive systems in the paleontological record until well after the Cambrian, they added. Associated with this shift, there was an increase in very well-preserved fossils with complex digestive systems, particularly among early arthropods.” On the other hand, Cambrian coprolites, recovered from about 36 deposits, are primarily used to investigate the digestive systems of early life.