IT HAUNTS the Amazon jungle with a giant bear's body and a monkey's face, clad in dark red fur and trailing a cloud of flying beetles. Its stench is disabling, its upright bulk disconcertingly humanlike and its roar like endless thunder. "When you hear it, you want to move in the other direction," said ornithologist David Oren. "It's absolutely terrifying." To rubber tappers and Indians in the forest's remote western fringe, the creature is the Mapinguari, the Amazon's version of the legendary Yeti or Bigfoot. No scientist has ever seen it, but Oren may be on the verge of proving the mythological animal actually exists. Scientists in the US and Germany this month are performing DNA tests on hair and feces Oren collected in Brazil's remote Acre state. If his suspicions are correct, the tests will reveal a biological shocker: The fabled monster is actually a species of giant ground sloth believed extinct for 8,500 years. "I have ev...