June 30 , 2016

By RYO KAGEYAMA

Elementary schoolboy Kakeru Funato is such an avid dinosaur buff that he frequently makes the long trip from his home in Gifu Prefecture to a dinosaur museum here.

Now, among all the dinosaur skeletons and fossils on display at the Fukui Prefectural Dinosaur Museum, the 11-year-old is hoping to see an important discovery he helped make in the field.

Kakeru spotted a fossil believed to be the skeleton of a newly discovered mammal species in the age when dinosaurs were roaming the Earth.

“I was stunned when I was told that a fossil of that kind is extremely rare,” he said. “I would like to return to the museum when it exhibits the fossil.”

The find of the skeleton of a mammal at the time of the dinosaurs is the first in the nation, although pieces of jawbones and teeth have turned up in this city and four other locations.

Researchers at Fukui Prefectural University and the museum said June 25 that the fossil excavated from a geological layer dating to about 120 million years ago in Katsuyama contained the skeleton of a small mammal creature.

They said the fossil contained 60 percent of the animal's skeleton. The announcement was made at a meeting of the Paleontological Society of Japan in the city.

“It is a significant discovery in terms of unraveling the living environment of mammals back then,” said Kazunori Miyata, a senior researcher at the museum.

Katsuyama is known as home to 80 percent of dinosaur fossils that have turned up in Japan.

The find dates to June 2014 when Kakeru noticed a rock the size of a fist when he visited a museum-affiliated excavation site in the city.

“It had an appearance of a fossil, looking different in color from other rocks,” recalled the sixth-grader at Nagamori-Minami Elementary School in Gifu.

The student could see what appeared to be the tooth of an animal on the surface of the rock.

The rock had been transported to the site after it was dug up in the city’s Kitadani district, where the skeletal fossil of Fukuivenator paradoxus, a small coelurosaurian theropod dinosaur, and other fossils were excavated.

A CT scan of the rock, done by the museum, showed bones spanning from parts of its head to the belly as well as those of the knee.

The skeleton measured 5 centimeters long and 2.6 cm wide and 1.3 cm thick.

Researchers estimated that the total length of the animal is about 13 cm, including its tail.

They believe the animal is an unknown herbivore species, given the characteristics of its teeth, and is related to the multituberculata, a long-extinct mammal.