This photo courtesy of the National Research Institute of Cultural Heritage (NRICH) shows the footprints of a vertebrate presumed to belong to the Cretaceous Period of the Mesozoic Era, commonly known as the age of dinosaurs about 100 million years ago. The footprints were found on a rock in the southeastern industrial city of Ulsan recently. The NRICH said on June 5, 2018, that 18 such footprints were found in Ulsan on June 1. (Yonhap)