Shigenori Kawano, 32, found last summer what was later identified as East Asia's oldest fossil of a giant alligator, dating from around 20 million years ago, on Oki Island in the Sea of Japan.
In mid-July, the researcher at Shimane Nature Museum of Mount Sanbe found a 30-cm rock on the Shimane Prefecture island's shore while studying local animal and plant life.
Kawano said that when he saw part of a bone exposed on the surface of the rock, he instantly knew it must be that of a reptile.