AP - In an undated photo provided by Professor Rodolfo Coria, a dog sits by a replica of the head of a Mapusaurus roseae at the Carmen Funes Museum in Plaza Huincul, Argentina. The dinosaur was discovered in the Patagonia region of Argentina and appears to be one of the biggest meat-eating dinosaurs known. (AP Photo/HO/Prof. Rodolfo Coria) Scientists are learning more about what appears to be one of the biggest meat-eating dinosaurs known, a two-legged beast whose bones were found several years ago in the fossil-rich Patagonia region of Argentina. One expert called the discovery the first substantial...