The oldest record of the Chinese alligator is a skeleton fragment found in western Japan. The fossil is estimated to be from the late Pliocene period, 3 million years ago (Mya). The skeleton showed that the species was larger at the time than it is currently, with a total length of at least . Alligators are believed to have moved into various parts of Japan either before 25 Mya or after 10 Mya and were extirpated from there during the Plio-Pleistocene period, due to Japan's increased isolation from the continent and harsh climate conditions.