Mammoth skeletons found at Mexico airport site

Experts said on Thursday the number of mammoth skeletons recovered at an airport construction site north of Mexico City has risen to at least 200, with a large number still to be excavated.

Archaeologists hope the site may help solve the mystery of their extinction.

Experts said that finds are still being made, including signs the lumbering animals may have been butchered by humans somewhere between 10,000 and 20,000 years ago.

There are so many mammoths at the site of the new Santa Lucia airport that observers have to accompany each bulldozer that digs into the soil to construct a new airport, to make sure work is halted when mammoth bones are uncovered.

"We have about 200 mammoths, about 25 camels, five horses," said archaeologist Rubén Manzanilla López, of the National Institute of Anthropology and History, referring to animals that all went extinct in the Americas.

The site is only about 12 miles (20 kilometres) from artificial pits, essentially shallow mammoth traps, that were dug by early inhabitants to trap and kill dozens of mammoths.

Manzanilla López said evidence is beginning to emerge that suggests that even if the mammoths at the airport might have died natural deaths after becoming stuck in the mud of the ancient lake bed, their remains may have been carved up by humans, somewhat like those found at the mammoth-trap site in the hamlet of San Antonio Xahuento, in the nearby township of Tultepec.

While tests are still being carried out on the mammoth bones to try to find possible butchering marks, archaeologists have found dozens of mammoth-bone tools like the ones in Tultepec.

Archaeologist Joaquin Arroyo Cabrales said part of this investigation will also allow researchers to understand what caused the extinction of their animals, whether it was climate change or the presence of humans.

The site, near Mexico City, now appears to have outstripped the Mammoth Site at Hot Springs South Dakota, which has about 61 sets of remains, and was the world's largest find of mammoth bones.

Large concentrations have also been found in Siberia and at Los Angeles' La Brea tar pits.

For now, the mammoths seem to be everywhere, and may slow down, but not stop work on the new airport.

The institute began digging in three large but shallow areas in October when work started to convert an old military airbase into a civilian airport.

The airport project is scheduled for completion in 2022, at which point the dig will end.