An ancient cradle of evolution may have been discovered in the striped cliffs of the Grand Canyon.
Paleontologists have found an exceptionally well-preserved trove of fossils in the greenish shales of the Bright Angel Formation. Today, these shales overlook the Colorado River from various points throughout the canyon, but they formed roughly half a billion years ago, during the Cambrian Period.
The fossilized fauna include sophisticated organisms like a newly identified species of penis worm with a retractable mouth, as well as mollusks and crustaceans that share similarities with modern animals, researchers report July 23 in Science Advances. The fossils paint a picture of a thriving ecosystem in