Earth Notes: Flagstaff Fossil Trackway Reveals Details About Animal Movement

Jun 2, 2021

Last year, crews were excavating the site of a new apartment complex in Flagstaff when something caught the eye of  equipment operator Spencer Phillip. Impressed on the surface of a big block of red stone were what appeared to be animal tracks.

A reptile trackway found at a construction site in Flagstaff is thought to about 240 million years old
Credit Michael Collier

Realizing it was something unusual, they stopped work and called in local geologists to take a look. Turns out, the five-toed tracks were made by a reptile that walked across soft mud about 240 million years ago.

The five-ton piece of rock from the Moenkopi Formation was donated to the Museum of Northern Arizona and installed in the courtyard where scientists will study it.

Footprint tracks are significant because they offer a glimpse into how animals actually moved across the land in a moment in time. These particular tracks were likely made in the middle Triassic period by a reptile that was an immediate predecessor of the dinosaurs. David Gillette, a retired paleontologist at the museum says of the fossilized tracks, “This is where it all began.”

He and others will closely study the imprints for clues. They want to identify the species more precisely and figure out how the tracks were preserved. Gillette says he’s fairly certain the trackway was made by a single animal.

Similar prints have been found in other places on the Colorado Plateau, but this is the first of its kind discovered in Flagstaff. The tracks are on exhibit at the Museum of Northern Arizona for the public to see and learn about this rare evidence of past life on Earth.