It's the first time this gait has been found in this family of ancient crocs, which typically walked on four legs like modern-day crocodiles and alligators. Similar "enigmatic" footprints found at other sites in South Korea had been thought to belong to giant pterosaurs prehistoric flying reptiles walking on two legs. It's possible the animal primarily walked on two legs but was also able to walk on four. No two-legged prehistoric crocodiles had been found from this period, although the study said that crocs that walked on two legs may have roamed the Earth much earlier during the early Mesozoic era that started about 250 million years ago. They said the consistent absence of forelimb prints and the narrow trackway pointed to a new species that walked on two legs.