Paleontological resources in Grand Canyon's sediments are diverse. The semi-arid climate and cold temperatures deep within canyon caves have combined to create a perfect environment for preservation of ancient materials. Pleistocene and Holocene remains have been unearthed within many of these caves. Some of the paleofauna and paleoflora that have been found include algal mats and bacterial spores over a billion years old, mummified dung and hair about 11,000 years old, and a multitude of additional body and trace fossils from the Paleozoic Era, 550-250 million years ago. Also, sedimentary units exposed throughout the Canyon, are rich with marine fossils such as chrinoids and brachiopods.
It is illegal to remove fossils from Grand Canyon National Park. All caves are currently closed to visitation.