Bolivian farmer Primo Rivera had long wondered about the dents in a rocky hill near his home. Paleontologists solved the mystery this month: they are fossilized dinosaur footprints — the oldest in Bolivia.
"I used to come to look at the prints when I was a kid ... but I didn't know what had made them," said Rivera, 35, who lives in the southern province of Chuquisaca.
The fossilized footsteps that intrigued Rivera for two decades are thought to be about 140 million years old, much older than other dinosaur prints found in the Andean country.
"The footprints we've found are important because they're the oldest ever found in Bolivia ... and the oldest footprints of Ankylosaurus ever found in the Southern Hemisphere," said Argentine paleontologist Sebastian Apesteguia in Buenos Aires.
Apesteguia, who led a two-week expedition sponsored by Chuquisaca's regional government, thinks the footprints belong to three different kinds of dinosaurs, including Ankylosaurus, an armored herbivore.
He said some of the prints were about 14 inches long, suggesting that the dinosaurs were "medium-sized ... about 30 feet in length."
Close to the larger prints, the paleontologists found smaller ones that probably belonged to baby dinosaurs, indicating the offspring "were given some kind of care," Apesteguia said.
Rivera said he first spotted the imprints about 20 years ago, but could never figure out what they were.
A few years ago, he visited a dinosaur park near Sucre, Chuquisaca's regional capital, and noticed that the dinosaur footprints on show resembled the holes near his parent's home.
Sucre is renowned for having the largest set of fossilized dinosaur footsteps ever discovered.
When Rivera bumped into members of Apesteguia's team doing research near his village of Icla, and told them about the holes.
"It was a stroke of luck that this man had been intrigued by the footprints since he was a child," said paleontologist Pablo Gallina, who along with Apesteguia, works for Argentina's Felix de Azara Natural History Foundation.
