Another Kind of Bigfoot

Grallator track, Zion Museum Collection: ZION 15801

NPS photo / Scott Ireland

When dinosaurs walked in Zion National Park they left imprints in moist, muddy sediments near watercourses. These tracks remained exposed for a short while, allowing them to become drier and harder. Then the imprints slowly filled with contrasting sediments and eventually were preserved in rock. Subsequent erosion over millions of years removed rock layers exposing tracks like the one shown here.

Because fossilized dinosaur bones are usually not found along with the tracks, paleontologists give separate names to footprints and other trace fossils. Also, similar dinosaurs may leave nearly identical footprints, making it very difficult to determine the specific species of dinosaur.

 

NPS photo / David Tarailo

The Kayenta and Moenave rock layers contain most of the dinosaur tracks found in Zion. Unfortunately, the sites in Zion are fragile and extremely difficult to access, but paleontologists have provided information on their exciting finds.

The footprints found are of two distinct footprint types, both made by predatory dinosaurs walking upright on two legs.

 

Brad Wolverton/Utah Geological Survey

Grallator is a small (2-6 inches long), three-toed print left by a dinosaur walking on two legs. The most probable dinosaur for the creation of the Grallator track is Megapnosaurus, a lizard-like, 70-pound, carnivorous dinosaur about 10 feet long from the tip of the tail to nose.

 

Eubrontes track

NPS photo

Eubrontes (photo at right) is a larger three-toed print--generally 10 to 20 inches long--from a larger dinosaur such as Dilophosaurus.

Dilophosaurus was approximately 20 feet long from nose to tip of tail, and weighed up to 1,000 pounds. The name "dilophosaurus" means "double-crested lizard" for the pair of crests on the top of its skull.

 

Brad Wolverton/Utah Geological Survey

 

Dinosaur tracks provide clues to behavior and paleo-environments. A recent discovery west of Zion contains dozens of parallel trackways heading in the same direction, indicating migratory behavior of several species of dinosaurs along an ancient lakeshore. The tracks helped confirm the presence of Lake Dixie that existed nearly 200 million-years ago. The St. George Dinosaur Discovery Site--a world-class tracksite--is the best place in the Zion region to see these dinosaur tracks.

 

Learn more about how footprints become fossils

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