Grand Canyon has so much more than pretty scenery. It contains an amazing diversity of rock formations with an abundance of fossils hidden within. The sedimentary rocks exposed throughout the canyon are rich with marine fossils such as crinoids, brachiopods, and sponges with several layers containing terrestrial fossils such as leaf and dragonfly wing impressions, and footprints of scorpions, centipedes, and reptiles. Ancient fossils preserved in the rock layers range from algal mats and microfossils from Precambrian Time 1,200 million to 740 million years ago to a multitude of body and trace fossils from the Paleozoic Era 525-270 million years ago.
What about dinosaur fossils? Not at Grand Canyon! The rocks of the canyon are older than the oldest known dinosaurs. To see dinosaur fossils, the Triassic-aged Chinle Formation on the Navajo Reservation and at Petrified Forest National Park is the nearest place to go.
It is illegal to dig up, relocate, and/or remove fossils from Grand Canyon National Park. If you find a fossil, please leave it for others to discover and scientists to study. You are welcome to take a picture or make a drawing of the fossil, then go to one of the visitor centers to see if a park ranger can help you identify it.
Fossils are the preserved remains of ancient life, such as bones, teeth, wood, and shells. Trace fossils represent the presence or behavior of ancient life, without body parts being present. Footprints, worm burrows, and insect nests are examples of trace fossils.
Sedimentary rock contains fossils because it was built up layer upon layer, often trapping and preserving animals, plants, footprints, and more within the layers of sediment. If all the conditions are right, fossils are formed as the layers of sediment turn into rock.
With 32% of Earth’s geologic history and one billion years of fossil life found at Grand Canyon, this is a great place to study ancient environments, climate changes, life zones, and the geologic processes that formed the landscape as we see it today. The following are the most common and well known groups of fossils found at the canyon. Many more await our discovery.
With marine environments creating many of the sedimentary rock layers in the canyon over the past 525 million years, marine fossils are quite common. Species changed over time, but similar fossils can be found in most of the marine-based rocks at Grand Canyon.
Even though trilobites were relatively primitive animals, they had amazingly complex eyes. Many species had faceted eyes like an insect, using up to 15,000 lenses in one eye.
In the ancient seas these crinoids were so plentiful they formed "gardens" on the sea floor. Discs, individually or sometimes still stacked together, can be found in all the marine layers at Grand Canyon. These were the hardest parts of the animal and most readily preserved as fossils.
They lived on the ocean floor attaching themselves with strong threads or using the shape of the shell and/or ridges on top of the shell to stabilize them in soft mud or sand. A few species had long spines on either side that helped them to remain stable in faster currents or wave action.
Lacy and stick bryozoans similar to those in our oceans today, were also found in ancient seas. These colonial animals produce “lacy” structures on hard surfaces or “stick” structures that stood up into the water column. Each animal has its own chamber within the colonial structure from which it can extend feeding arms into the water column or retract them for protection. Bryozoans are passive filter feeders, collecting organic material and plankton from the water. Scientists sometimes refer to bryozoans as “moss animals” because when their arms are out feeding, they sometimes look like moss covering a surface.
Corals have a polyp shape, similar to its relative the jellyfish. It tucks its body into its skeleton and extends tentacles into the water column for feeding. Corals have a spiral of tentacles lined with nematocysts, or stinging cells, which can capture plankton floating by within reach.
Living attached to the sea floor, sponges are a colony of single-celled animals that act like a multi-cellular animal. Each individual animal has a specific job, from filtering water for food to protection. Fossil sponges exist because of a unique skeletal structure. Microscopic silica or calcium carbonate spicules, or interlocking spines, provided structural support. When the sponge died, the spicules clumped together and formed a silica mass. When hardened into rock the mass became a chert nodule. Chert is harder than the limestone rock it is embedded in, causing the nodules to protrude from the rock as erosion occurs. With so many sponges in the ancient seas, layers like the Kaibab Limestone are actually more resistant to erosion because of the chert nodules.
Several of the rock layers in the canyon are of terrestrial origin, including the Hermit Shale, Supai Group, Coconino Sandstone, and Surprise Canyon Formation.
The mudstones and siltstones of the Hermit Shale and Supai Group were laid down by a meandering system of rivers and streams in a semi-arid climate about 280 million years ago. The sand grains of the Coconino Sandstone were deposited by wind across large coastal sand dunes about 275 million years ago. Each of these layers has unique trace fossils and environmental features preserved in the rock. The Surprise Canyon Formation may be the most fossiliferous formation with petrified wood and bone fragments as just a few examples of fossils found.
Within the dunes of wind-blown quartz sand of the Coconino Sandstone, tracks of ancient animals are the most common fossils. Even though no bones have been found, these tracks contain an abundance of information about the animals that made them. Scorpions, millipedes, isopods, spiders, and mammal-like reptiles once scurried over these dunes. Their footprints tell the stories of running or walking across the sand, traveling up or down the dunes, whether the animal dragged its tail, how big the animal may have been based on its stride length, whether it had an upright or sprawling posture, and what kind of animals shared these dunes.
The semi-arid climate and cool temperatures deep within canyon caves have combined to create a perfect environment for preservation of more recent fossils. Pleistocene and Holocene remains have been unearthed within many of these caves, including 11,000 year old sloth bones, dung and hair, California condor bones and egg shell fragments, and pack rat middens. These recent remains help scientists understand more modern environmental conditions and climate change that affected the plant and animal communities within Grand Canyon.
All caves (and mine shafts), with the exception of the Cave of the Domes on Horseshoe Mesa, are currently closed to visitation. This is for the safety of visitors, the protection of fragile resources such as fossils and unique cave formations, and the preservation of bat habitat. In the 1970s many fossils were lost due to careless visitors leaving a fire burning in Rampart Cave. These resources are irreplaceable and need all of us to help protect them.
Grand Canyon fossil books are available from Grand Canyon Association's online bookstore:
Other websites with fossil information include:
Did You Know?
The Cambrian seas of the Grand Canyon were home to several kinds of trilobite, whose closest living relative is the modern horsehoe crab. They left their fossil record in the mud of the Bright Angel Shale over 500 million years ago.