TULTEPEC, MEXICO—The Guardian reports that two pits containing hundreds of 15,000-year-old butchered bones from more than a dozen mammoths have been discovered in northeastern Mexico ahead of the construction of a landfill site. The straight-sided pits, which measure nearly six feet deep and 80 feet in diameter, are thought to have been dug as traps to catch the enormous herbivores, according to Pedro Francisco Sánchez Nava of Mexico’s National Institute of Anthropology and History. It had been previously thought that Pleistocene hunters only occasionally killed mammoths when they found them trapped in bogs or swamps. Numerous traps were probably dug in a line in order to increase the chances of capturing an animal, added archaeologist Luis Córdoba Barradas. He suggests that groups of 20 to 30 hunters might have separated an individual mammoth from a herd with torches and branches and then driven it toward the traps. For more on early humans' hunting of mammoths, go to "Leftover Mammoth."