In a stunning fossil discovery in Japan, paleontologists unearthed a nearly complete skeleton of a duck-billed dinosaur that lived approximately 72 million years ago.
A nearly-complete skeleton of the duck-billed dinosaur Mukawaryu. Image credit: Hobetsu Musem / Hokkaido University Museum.
Duck-billed dinosaurs, or hadrosaurids, are members of the family Hadrosauridae.
They were common plant-eaters in the Upper Cretaceous epoch (100.5 million to 66 million years ago) of what are now Asia, Europe and North America.
Complete hadrosaur skeletons have been unearthed on these continents, but it is rare for a complete skeleton of a terrestrial dinosaur to be discovered in a marine stratum.
In 1936, a complete skeleton of the hadrosaur Nipponosaurus sachalinensis was found in marine sediments in Sakhalin by Professor Takumi Nagao of Hokkaido Imperial University (predecessor of Hokkaido University).
It had been the only such fossilized dinosaur from a marine stratum that was assigned a name.
The latest discovery, nicknamed ‘Mukawaryu’ (Mukawa dragon), represents the third such discovery in the world.
Hokkaido University Museum paleontologist Prof. Yoshitsugu Kobayashi and his colleagues from Hokkaido University and Hobetsu Museum found parts of Mukawaryu’s skeleton at a site in Mukawa near the city of Tomakomai, Hokkaido.
According to the team, Mukawaryu was approximately 26 feet (8 m) long and weighed 7 tons.
“Mukawaryu represents the second complete dinosaur skeleton unearthed in Japan after Fukuivenator paradoxus, an 8-foot (2.5 m) theropod from the Lower Cretaceous,” the researchers said.
“Mukawaryu is the first complete skeleton of a herbivore from the Upper Cretaceous and from a marine stratum in Japan.”
“We first discovered a part of the fossilized Mukawaryu skeleton in 2013, and after a series of excavations, we believe we have cleaned more than half of the bones the dinosaur had, making it clear that it is a complete skeleton,” Dr. Kobayashi said.
