A pre-historic human skeleton has been found in a cave system that was flooded at the end of the last ice age 8,000 years ago, according to an archaeologist and cave diver on Mexico's Caribbean coast. Archaeologist Octavio del Rio said he and fellow diver Peter Broger saw the shattered skull and skeleton partly covered by sediment in a cave near where the Mexican government plans to build a high-speed tourist train through the jungle. Given the distance from the cave entrance, the skeleton couldn't have gotten there without modern diving equipment, so it must be over 8,000 years old, Del Rio said. Some of the oldest human remains in North America have been discovered in the sinkhole caves known as "cenotes" on the country's Caribbean coast that are threatened by the Mexican government's Maya Train tourism project.