I totally get what you are saying. However, it doesn't take a concerted effort of any kind for dead animals to turn up. Especially if supposedly Chupas are dinosaurs held over from prehistoric times. a dead one would have been found at some point, with or without anybody actively looking for it. Just because our knowledge of a locality's flora and fauna is incomplete doesn't give anyone license to claim that fantastic animals exist simply based on that. Lack of evidence cannot be used as evidence itself.