Trilobite Tracks
(and other traces)
of the Grand Canyon



There are no trilobites in the San Joaquin Valley, the rocks there just aren't old enough. However, located only five hours drive away from the valley center is Las Vegas, Nevada, which is the usual starting point for a whitewater raft trip down the Grand Canyon - a place where there are plenty of trilobite trace fossils. Deer Creek Falls sits at about the midway point when floating down the canyon on a raft, and a steep climb to the top of the falls, followed by a short hike up the canyon at the top that feeds the falls, leads to a small valley that is a wonderland of trace fossils, including some made by trilobites.

Trilobites are ancient crab-like arthropods (invetebrates with legs) that lived in ancient oceans from Cambrian to Devonian times, and their traces are found in the Grand Canyon in outcrops of the Cambrian-age Tapeats Sandstone. Three types of trilobite trace fossils can be found at the falls if you look on the underside of ledges lining the trail. When trilobites plowed across the surface of the Tapeats sediment like a bulldozer they left behind parallel furrows adorned with transverse scratch marks made as their feet dug into the furrows for traction. These traces are known as Cruziana. They also scurried across the surface of the Tapeats ocean floor raised up off the bottom by their legs, and left parallel trackways of shallow, short scratch marks called Diplinichtes. They also left resting marks were they hunkered down in depressions in the sediment. These are called Rusophycos.

Below are photos of some of the trilobite traces found along the trail above Deer Creek Falls. In addition, some photos are included of other traces, modern and ancient, that are associated with the trilobite tracks. Elsewhere on a canyon float trip you might also get a chance to see some dinosaur tracks (another type of trace fossil) at a place called Hermit Rock.


Trilobite fossil on a shale slab sold on EBay
We have no idea where it came from.
(or for that matter where it went)

Cruziana in outcrop (Tapeats Sandstone)

Rusophycos in outcrop

Both left and above: Specimens from the Cambrian Tapeats Sandstone, on the Deer Creek Falls Trail, Grand Canyon, Utah. The trace fossils are exposed beneath ledges that stick out along the trail.

Diplichnites in outcrop
Cambrian Elk Mound Group, Wisconsin.
Trilobites can make traces like these also,
but we did not see any in the Grand Canyon.
(photo from Wikipedia)

Cruziana (Tapeats Sandstone)

Technically most geologists would not consider Indian Pictographs to be trace fossils.
On the other hand though, they do represent traces of life from the distant past.
These are found near the trace fossils in the Cambrian Tapeats Sandstone.

Thalassinoides (Tapeats Sandstone)
The odd depressions in the upper right corner
may be another trace fossil of some sort.