A glyptodont shell found in Carlos Spegazzini, Buenos Aires Province, Argentina on December 29, 2015 --------------------------------------------------------------------------------------------------------------------------------------------- A passer-by on Christmas Day found a meter-long shell on a riverbank in Argentina which may be from a glyptodont, a prehistoric kind of giant armadillo, experts said Tuesday. A local man thought the black scaly shell was a dinosaur egg when he saw it lying in the mud, his wife Reina Coronel told AFP. Her husband Jose Antonio Nievas found the shell beside a stream at their farm in Carlos Spegazzini, about 40 kilometers (25 miles) south of the capital Buenos Aires. "My...