June 30 , 2016

The partial remains of a fossilized skeleton of a herbivorous mammal has been discovered in a layer of earth from the Lower Cretaceous, about 120 million years ago, in Katsuyama, Fukui Prefecture, researchers announced Saturday.

It is rare that an entire fossil of a mammal from the era of the dinosaurs is found, according to Fukui Prefectural University and the Fukui Prefectural Dinosaur Museum.

The skeleton was discovered in June 2014 by Kakeru Funato, then an elementary school student in the fourth grade, who was attending a fossil excavation event in the Katsuyama Dinosaur Forest Park.

A computerized tomography examination by the university and the museum determined that it was the skeleton of a small grass-eating mammal from an extinct group called Multituberculata, which had similar characteristics to Rodentia.

“A fossil skeleton of a Multituberculata mammal is very rare,” Kazunori Miyata, associate professor of Fukui Prefectural University, said. “It will serve as a very important sample that helps unravel the diversification and evolution of Multituberculata mammals.”

The animal is estimated to have had a body length of about 13 centimeters when it was alive, according to the museum and the university. The portion of the well-preserved fossil is 5 centimeters long, 2.6 cm wide and 1.3 cm in height.

Judging from its teeth and body size, it might be a species that had never been discovered before, the researchers said.

In the Katsuyama park, rocks are brought in from an excavation site in the city so the general public, including children, can experience what it is like to be a paleontologist. Funato, the 11-year-old boy from the city of Gifu, took part in the event with other members of his family.

He discovered the rare find after cracking into a rock.

“When I found it, I thought it might be a discovery of a sort,” he said. “But I’m astonished to learn it was an important enough fossil to make news.”

Funato came to like dinosaurs after looking at a picture book while he was in kindergarten.