Fossil of ‘One of Last Dinosaurs’ Found on Island in Kagoshima

Wednesday, June 27, 2018

Part of a thighbone of a type of giant plant-eating hadrosaur that lived 70 million years ago and found in Kamikoshikijima island in Satsuma-Sendai, Kagoshima Prefecture (Provided by the Satsuma-Sendai city government)

A fossil found on an island here two years ago was identified as from “one of the last dinosaurs” before their extinction 66 million years ago.

Researchers said the piece of thighbone was from a type of giant plant-eating hadrosaur that was at least 10 meters long.

It was discovered in Kamikoshikijima island, which lies to the west of southern Kyushu and is administered by Satsuma-Sendai city.

The finding was announced by a team of researchers from Satsuma-Sendai, Kumamoto University, the National Museum of Nature and Science, Tokyo, and other institutes at a meeting of the Paleontological Society of Japan in Sendai, Miyagi Prefecture, on June 23.

The fossil was found in exposed rock by Yuka Miyake, a researcher with the Satsuma-Sendai city government, in a coastal area of the island's Kamikoshiki district in July 2016.

She and her colleagues spent about a year extracting the fossil from the rock. It measures 70 centimeters and 28.5 cm at its widest point. The thighbone would have measured more than 120 cm.

Based on the geological layer where it was found, experts said this particular dinosaur lived around 70 million years ago in the last stages of the Mesozoic Cretaceous period.

Hadrosaurs thrived across the Eurasian Continent and North America in the latter part of the Cretaceous.

It was the 10th hadrosaur discovery in Japan and on a par with one of the same age excavated in Awajishima island, Hyogo Prefecture, in 2004.

Dinosaur fossils have also been found in Hokkaido, the northernmost main island of the Japanese archipelago, evidence that the giant creatures roamed a vast area stretching north to south in the vicinity of Japan.

“It is a clue that may enable us to grasp the extent of the diversity of dinosaurs that flourished in Asia,” Miyake said.

The research team also reported at the meeting that dinosaurs thrived in a wet climate and areas with easy access to water, such as mangrove swamps.

Numerous fragments of carnivorous dinosaurs dating to older periods have been found in Shimokoshikijima island, which is close to Kamikoshikijima.

It was the first dinosaur discovery on Kamikoshikijima.

Researchers said they expect more fossil discoveries from the era closer to the period dinosaurs became extinct as the geological formation of Kamikoshikijima is more recent than that of Shimokoshikijima due to crustal movement.

The team refused to pinpoint where the hadrosaur fossil was found to protect the site.

The fossil will go on public display at the city government's Kashima branch office in Shimokoshikijima from July 15. Admission is free.