Japan’s largest dinosaur skeleton found in 72 million-year-old marine deposits, belongs to a new genus and species
Japanese researchers have discovered the largest dinosaur skeleton in the country underneath 72 million-year-old marine deposits in the town of Mukawa.
The duck-billed dinosaur belongs to a new genus and species of a herbivorous hadrosaurid dinosaur, the Hokkaido University said in a release, owing to the low position of the cranial bone notch, the short ascending process of the jaw bone and the anterior inclination of the neural spines of the sixth to twelfth dorsal vertebrae.
Part of the dinosaur's tail was discovered during a joint excavation by the Hobetsu Museum and Hokkaido University Museum in 2013 before subsequent attempts unveiled a nearly complete dinosaur skeleton.
According to a study published in Scientific Reports, the researchers named the dinosaur "Kamuysaurus japonicas."
CNN reports that the name comes from "kamuy," the word for deity in Ainu, the language of the indigenous people of northern Japan; "saurus," meaning reptile in Latin; and "japonicus" for Japan.
The researchers led by Yoshitsugu Kobayashi from the Hokkaido University Museum analyzed the skeletal bones and found that the dinosaur, aged 9 or above, was most likely an about 8metre long.
It weighed either 4 or 5.3 tons, about the weight of an Asian elephant, depending on whether it walked on two or four legs respectively.
Comparative and phylogenetic analyses on 350 bones and 70 taxa of hadrosaurids led to the discovery that the dinosaur belonged to the Edmontosaurini clade, spread across both Asia and North America, and is closely related to Kerberosaurus unearthed in Russia and Laiyangosaurus found in China.
“The frontal bone, a part of its skull, has a big articular facet connecting to the nasal bone, suggesting the dinosaur may have had a crest. The crest, if it existed, is believed to resemble the thin, flat crest of Brachylophosaurus subadults, whose fossils have been unearthed in North America,” the release said.
“The study also shed light on the origin of the Edmontosaurini clade and how it might have migrated. Its latest common ancestors spread widely across Asia and North America, which were connected by what is now Alaska, allowing them to travel between the two continents. Among them, the clade of Kamuysaurus, Kerberosaurus and Laiyangosaurus inhabited the Far East during the Campanian, the fifth of six ages of the Late Cretaceous epoch, before evolving independently.”