Cloud of scholarly dust rises over ancient footprints claim Tuesday, April 25, 2006 BRADLEY T. LEPPER Are the footprints of surprisingly ancient Americans preserved in 40,000-year-old volcanic ash in southern Mexico? In December, an article in the journal Science cast a cloud of doubt over that claim. The authors, Michael Waters and Paul Renne, argue that the ash dated to 1.3 million years ago, much too old for humans on this continent, and that the so-called footprints were nothing more than marks made by the tools of modern workers quarrying the stone with crowbars. Now, Silvia Gonzalez, an archaeologist from...