National / Science & Health

Fossilized dinosaur teeth unearthed in Nagasaki Prefecture


Fossilized teeth belonging to a plant-eating dinosaur have been discovered in Nagasaki Prefecture, offering fresh clues about the reptile and the ecosystem 81 million years ago, a local museum said Tuesday.

Thirty-five fossilized teeth have been unearthed from a geological layer dated to the late Cretaceous Period on the west bank of the Nagasaki Peninsula, according to the Fukui Prefectural Dinosaur Museum and the city of Nagasaki.

The teeth are believed to be those of an herbivore similar to the hadrosaur, or duck-billed dinosaur, which is known to have had a dense array of flat teeth for chewing.

Of the 35 teeth, 34 were found within a radius of several meters, the museum said.

“We can assume there were a number of dinosaurs in the area. If fossils of plants and animals are found nearby, we can replicate the ecosystem of the time,” a museum official said.

The height of the largest tooth found was about 1.7 centimeters, and it had a width and depth of around 1 cm.

As the surface of each tooth was either flat or dented, with roots that were not dichotomous, the museum judges the fossils to belong to an ornithopod grazing dinosaur.

It is believed that when an ornithopod’s teeth wore down, they fell out naturally and were replaced by new teeth.

The fossils will be showcased at the Gunkanjima Museum in the city of Nagasaki for four days from Thursday, and at the Nagasaki Science Museum from July 25 to Sept. 18. Six replicas will be displayed at the Fukui museum from Wednesday.

Fossils of similar dinosaurs have been excavated in six other prefectures, including Iwate and Fukushima, and the complete skeleton of a Hadrosaurid was unearthed in Mukawa, Hokkaido.