Photo/Illutration A fossil skeleton of a Corythosaurus dinosaur stored at the Okayama University of Science’s Museum of Dinosaur Research in Okayama. Missing parts were artificially reconstructed. (Ayaka Kibi)

OKAYAMA—A U.S. fossil entrusted to a university museum here was from a Corythosaurus dinosaur, the first such specimen discovered outside of Canada, researchers said.

“The finding proved to be important for figuring out the distribution of Corythosaurus,” said Ryuji Takasaki, a researcher of vertebrate paleontology at the Okayama University of Science.

The university’s Museum of Dinosaur Research was put in charge of the fossil, which was unearthed from a farm in the U.S. state of Montana in 1989.

Almost all skeletal components from the head to the tail had been preserved in excellent condition.

An artist’s rendition of a Corythosaurus dinosaur (Provided by Riku Kadoshima, an Okayama University of Science graduate)

Fossilized remains of Corythosaurus had been found almost exclusively at Dinosaur Provincial Park in the western Canadian province of Alberta.

The park’s geological formation extends south across the border to Montana.

But no evidence of Corythosaurus living in the United States had been uncovered until now.

Corythosaurus, a “duck-billed” herbivore dating back 76 million years, appeared in large numbers during the latter half of the Cretaceous Period. The hadrosaur had an 8-meter-long body and a large round crest on its head.

One problem in identifying the fossil at the Okayama museum was that it did not have the characteristic crest.

The museum re-examined the broken pieces of the dinosaur kept in a storage room. Bone fragments forming part of a crest were found, and the specimen was identified as that of Corythosaurus.

“The discovery may help deepen the understanding of the ecosystem in that period,” said Kentaro Chiba, a lecturer of vertebrate paleontology at the university.

Four bone fragments at the top right were identified as part of the crest a Corythosaurus after re-examination. It was previously unknown which parts of the dinosaur these fragments were from. (Ayaka Kibi)

The Okayama University of Science was entrusted with fossilized samples, including the Corythosaurus, by the Hayashibara Museum of Natural Sciences in Okayama, which closed in 2015.

“Research on entrusted cultural properties falls within our responsibility, so we feel rewarded for the latest achievement,” said Shinobu Ishigaki, director of the Museum of Dinosaur Research. “The specimen is on display at the museum free of charge, and I would like many people to view it.”

The finding has been published in the specialized international journal Anatomical Record.