(CNN) — Dinosaur footprints dating back 100 million years have been discovered in southwestern China after a sharp-eyed diner spotted them in a restaurant's outdoor courtyard.
Several stone pits at the restaurant in Leshan, Sichuan province, contained the footprints of two sauropods, a type of dinosaur that lived during the early Cretaceous period, said Lida Xing, a paleontologist and associate professor at the China University of Geosciences.
Xing's team confirmed the discovery on Saturday using a 3D scanner.
Sauropods, known for their long necks and tails, were the largest animals ever to walk the Earth. They could grow to the length of three school buses and were so heavy the ground must have shaken as they walked.
The two sauropods who left the footprints probably measured about 8 meters (26 feet) in body length, Xing said.
The footprints of two sauropods, discovered in Leshan, Sichuan, China.
Courtesy Lida Xing
Though many dinosaur fossils from the Jurassic period have been uncovered in Sichuan, far fewer fossils from the Cretaceous period have been found. The Cretaceous period is when "dinosaurs really flourished," Xing said, adding, "this discovery is actually like a jigsaw, adding a piece of evidence to Sichuan's Cretaceous period and the diversity of dinosaurs."
China's rapid development in recent decades has made paleontology -- the study of ancient life through fossil records -- more difficult, Xing said.
"It's rare to find fossils in the city, because they were all covered by buildings," he said. His team aims to visit sites of potential discoveries within 48 hours of receiving a report, for fear they "may get destroyed by construction work in days," he added.
Before it was a restaurant, the location was used as a chicken farm, with the dinosaur footprints buried by layers of dirt and sand -- shielding them from erosion and weather damage.
Lida Xing and his team visited the site after receiving a report of possible dinosaur footprints from a diner.
Courtesy Lida Xing
The dirt was only removed about a year ago when the restaurant opened. The owner liked the natural look of the uneven stone, so left it untouched instead of leveling it with cement, Xing said.
As a result, "these footprints were well protected," Xing said. "When we went there, we found that the footprints were very deep and quite obvious, but nobody had thought about (the possibility)."
The restaurant owner has now fenced off the site to prevent people from stepping on the pits, and may build a shed to protect the footprints further, Xing said, adding that it was a welcome sign of greater scientific interest among the public.
"If it were 10 years ago, nobody would send me photos of suspected dinosaur (fossils or footprints)," he said. "But now, I get quite a few from normal citizens, and I confirm several dinosaur footprints every year."