The researchers at the Mayan acropolis of Tonina working in the jungles of the southern state of Chiapas discovered a sarcophagus which could help clear up the mystery of the fall of the Maya civilisation.
Juan Yadeun, who heads the team in Ocosingo, said that the sarcophagus measures two metres long, 70 cm wide and 60 cm deep, and it is similar to the "Red Queen" discovered in 1994 in Palenque, Chiapas.
The archaeologist said that the object dates from 840-900, the epoch when the last known Maya inscription was made.
"In 840 AD there was a very important transformation in the Maya cities. They stopped producing sculptural representations and inscriptions, which has been interpreted as a massive abandonment of the settlements," Yadeun said.
He said that the sarcophagus "will contribute new elements on the collapse of the ancient Maya civilisation, (like) knowing with precision who were the causes of the decline, if it was local people influenced by groups from the Altiplano, coming directly from this part of Mesoamerica or from what today is (the southeastern state of) Tabasco".
The sarcophagus contains a jar and a skull with traces of deformities and broken in several spots, as well as limb bones arranged in the form of a cross, apparently of "a personage of the top hierarchy, probably a woman or a child".
Within the crypt was also found a spherical jar with a lid containing bones that were boiled and fragmented, placed there some 500 years ago by Tzeltal Indians who settled in the area, restored some of the buildings for their own use and opened the local tombs to remove the objects within and place inside new items, including offerings.
Yadeun said that a theory suggests that the Maya civilisation disappeared after the arrival of Toltec people from the central high plateau.
"This involved groups of a corporative character, large armies that perhaps came from the Puebla-Tlaxcala area (in central Mexico), the Gulf Coast and Oaxaca (in the south), linked to Tula at the same time," he said.
Yadeun said the ninth century brought a very important transformation in the Maya cities, a situation that suggests that "in those times in ancient Mexico a revolution was brewing, with the fall of the dynasties and the coming to power of groups of warriors".
This site, closed to the public since its discovery four years ago, also contains a mural that has been restored and contains the history of the pyramid that forms part of a complex measuring 320 metres along each side and 63 metres high structure.