In May, Mexican archaeologists have found a trail of 13 fossilized footprints in travertine (a white rock) in a valley in Coahuila desert in northern Mexico, which could be among the oldest in the Americas. "The footprints were made by hunter gatherers who are believed to have lived thousands of years ago in the Coahuila valley of Cuatro Cienegas, 190 miles (306 kms) south of Eagle Pass, Texas," said archaeologist Yuri de la Rosa Gutierrez of Mexico's National Institute of Anthropology and History.

"We believe (the footprints) are between 10,000 and 15,000 years old,'' De la Rosa said.

"We have evidence of the presence of hunter gatherers in the Coahuila desert more than 10,000 years ago.''

The age of the footprints is to be precisely determined at a laboratory in Bristol in Great Britain. The oldest footprints found in the Western hemisphere are in Chile, and were determined to be 13,000 years old. 6,000-year old footprints were found in California, Brazil and Nicaragua. So, these seem to be oldest footprints in North America.

The oldest known human footprints are those found in Laetoli, in Tanzania, made 3.5 million years ago. But the Laetoli footprints did not belong to modern human, in fact not even to Homo genus, but to its ancestor, Australopithecus. Each Mexican footprint is 10 inches (27 cm) long and under an inch (2 cm) deep, spread over a distance of 30 feet (10 meters). "It is likely they were imprinted in mud and preserved by some rapid change in the environment," said Arturo Gonzalez, director of the Desert Museum from Saltillo, in state capital of Coahuila.

"There must have been a natural phenomenon to rapidly cover them so they were not rubbed out and were perfectly preserved,'' Gonzalez said.