Fossil footprints could be monumental.

Dinosaur tracks found on vacant property in a small Utah town could soon be protected as part of a new U.S. national monument.

Sheldon Johnson, who owns the 50-acre parcel of land in St. George, discovered the evidence of ancient life while excavating a hill in February 2000. Johnson's original plans would have converted,the plot, next to a school, into an industrial park.

"It's a remarkable site," says James I. Kirkland, the state paleontologist of Utah. More than 100 footprints of meat-eating theropod dinosaurs have been uncovered there, as well as grooves where the creatures' tails dragged in the mud. Says Kirkland: "Hats off to Mr. Johnson," who, rather than helping to preserve the site, could have quietly bulldozed the fossils into oblivion.

The fossil tracks range from 5 to 18 inches in length and appear to have been formed when the animals wandered through deep mud along the shore of an ancient lake. Some of the footprints are deep enough that they preserve the imprint of a vestigial toe, located in a position on the leg similar to that of a dog's dewclaw, says Kirkland.

Fossils other than bones, such as footprints, often provide important clues about the lifestyle and environment of dinosaurs and other prehistoric life (SN: 6/9/01, p. 362). Large salt crystals are embedded in the 205-million-year-old sediments containing the prints. The salt indicates that the lake went through cycles of significant evaporation, a sign that the climate was generally arid. No tracks of plant-eating dinosaurs appear at the site, but fossils of fish about 3 feet long abound in the lake sediments. It's possible that the meat eaters that left the footprints waded into the lake to dine on fish, just as some bears do today, says Kirkland.

In the 15 months following Johnson's discovery, more than 140,000 people--including tourists from every state and 54 countries--visited the site, causing frequent traffic jams in the city of 50,000. Johnson and the city have erected a fence around the plot, which is now being operated 7 days a week by volunteers.

Under federal law, either President Bush or Congress could declare the site a national monument, says Michael Correia, a spokesman for the U.S. House of Representatives' Committee on Resources. The chairman of that committee is James V. Hansen, congressman for the Utah district that includes St. George. Residents are also considering asking corporate sponsors to help develop the fossil site into a full-fledged tourist attraction, Correia notes.