A New Duck-Billed Dinosaur, ‘Kamuysaurus japonicus’ – Identified

Eddie Gonzales Jr. – MessageToEagle.com – A new kind of duck-billed dinosaur has been unearthed from 72 million-year-old marine deposits in Mukawa Town in northern Japan.

According to Hokkaido University’s press release, a partial tail of the dinosaur was first discovered in the outer shelf deposits of the Upper Cretaceous Hakobuchi Formation in the Hobetsu district of Mukawa Town, Hokkaido, in 2013.

Reconstruction of Kamuysaurus japonicus (Kobayashi Y., et al, Scientific Reports, September 5, 2019)

This nearly complete skeleton is the largest dinosaur skeleton ever found in Japan. The scientists have discovered named the dinosaur Kamuysaurus japonicas, but it is best known as “Mukawaryu,” nicknamed after the excavation site.

Researchers analyzed 350 bones and 70 taxa of hadrosaurids, which led to the discovery that the dinosaur (a herbivorous hadrosaurid dinosaur) belongs to the Edmontosaurini clade, and is closely related to Kerberosaurus found in Russia and Laiyangosaurus found in China.

They determined that Kamuysaurus japonicus, has three unique characteristics that are not shared by other dinosaurs in the Edmontosaurini clade:

1) the low position of the cranial bone notch,

2) the short ascending process of the jaw bone, and

3) the anterior inclination of the neural spines of the sixth to twelfth dorsal vertebrae.

According to the team’s histological study, the dinosaur was nine-year-old, about 8 meters long and weighed 4 tons or 5.3 tons (depending on whether it was walking on two or four legs respectively) when it was alive.

A fossilized skeleton of Kamuysaurus japonicus was first discovered in the Hobetsu district of Mukawa Town, Hokkaido, in 2013. Ensuing excavations found a nearly complete skeleton (above), currently the largest dinosaur skeleton ever found in Japan.

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 discovered in North America.

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.

The research team’s analyses pointed to the possibility that ancestors of hadrosaurids and its subfamilies, Hadrosaurinae and Lambeosaurinae, preferred to inhabit areas near the ocean, suggesting the coastline environment was an important factor in the diversification of the hadrosaurids in its early evolution, especially in North America.

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Written by Eddie Gonzales Jr. – MessageToEagle.com Staff