http://cameronmccormick.blogspot.com/2010/03/stupendemys-giant-amongst-mega-turtles.html Stupendemys: Giant Amongst Mega-Turtles] Based on this specimen, a larger but less complete fossil carapace would have had an estimated total carapace length of more than 3 meters , making it one of the largest turtles that ever existed, rivaling even Archelon.