HEAVY TRAFFIC is nothing new to Stafford County. So, the next time you are stuck in line at the Falmouth stoplight, you might consider just how lucky you are.

If you had been going home from work during the Cretaceous Period--about 110 million years ago--you might be sharing the highway with a Brontopodus birdi.

Talk about heavy traffic

That dinosaur weighed about 20 tons, grew to 70 feet in length and could dine on tree leaves at about 60 feet--or the height of a six-story building.

And one of those creatures left tracks along the Rappahannock River just about 21/2 miles from the Chatham Bridge, according to Jon Bachman, who spoke to the Stafford Historical Society last week about the county's prehistoric animal life.

Bachman, a career educator and amateur paleontologist, said vertebrates were abundant and diverse in Stafford County and the Rappahannock River region during the Cretaceous Period, which lasted from about 125 million to about 65 million years ago.

"From what we have gathered, the group of animals we have identified represents one of the more complete set of animals from that era in North America," Bachman said.

"Stafford County offers a rare window into an important time period. The mix of animals that was here makes this area unique among track sites elsewhere in the world."

Bachman said tracks from 10 different species of dinosaurs have been found in the Stafford area, either near Potomac Creek or along the Rappahannock River shoreline.

The largest of that group would have been Brontopodus birdi. The smallest would have been Hypsiloichnus marylandicus, which Bachman said was about the size of a small pony. Along the Rappahannock, there also were tracks from a species of crocodile that was about 35 feet long, plus a frog and a turtle from the same era.

"Many people think all dinosaurs were huge," said Bachman. "But that's just because the big ones left tracks that are better preserved. Most dinosaurs were much smaller--many about the size of a collie dog."