A new dino with duckbill

72-million-year-old hadrosaur is the largest dino skeleton ever found in Japan

This is what Kamuysaurus japonicus might have looked like. © Kobayashi et al., 2019 / Scientific Reports
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New family member: Researchers in Japan have discovered the 72-million-year-old fossil of a previously unknown hadrosaur species. The duckbill dinosaur was about eight meters long in life, weighed at least four tons and lived near the ocean. The fossil, according to the team, provides new insights into the evolution of these successful herbivores - and sets a record. Because the find is the largest Dino skeleton ever found in Japan.

The Hadrosaurs belonged to the most successful dinogroups of the Cretaceous period: The herbivores, also known as the duckbill dinosaurs, conquered large parts of the planet during the Earth's Middle Ages - their fossils have already been found in North and South America, Asia, Europe and even the Antarctic discovered. Researchers believe that hadrosaurs were the most common herbivorous dinosaurs on earth at the end of the Cretaceous.

Eight-meter-long colossus

A new member of this dinosaur group now presents the team of scientists headed by Yoshitsugu Kobayashi from Hokkaido University. In the so-called Hakobuchi Formation in Mukawa, Japan, they excavated the almost complete skeleton of a previously unknown hadrosaur species. Initially, only part of a tail had been found in 2013. But gradually more and more bones appeared and finally it was clear: It was the largest dinosaur skeleton that was ever discovered in Japan.

To learn more about the Giant Dino, researchers looked more closely at his mortal remains for their study. The analyzes revealed that the 72-million-year-old hadrosaur was around eight meters long during its lifetime and weighed between four and five tons. It was probably a mature male at the age of nine or older, the team reports. On its head, the species baptized Kamuysaurus japonicus might have carried a small comb - similar to that known by young Brachylophosaurus.

Habitat coast

Comparisons with fossils of other duckbill dinosaurs revealed that Kamuysaurus japonicus belongs to the Edmontosaurini. He is therefore closely related to the Kerberosaurus found in Russia and the Laiyangosaurus from China. The researchers suspect that the ancestors of these dinosaurs originally developed in North America and populated there from Asia. Since Asia and North America were then connected by today's Alaska, the animals could migrate back and forth between the two continents. display

It is interesting in this context that Kamuysaurus japonicus was living in a marine environment during his lifetime. As Kobayashi's team explains, there are indications that the ancestors of this dinosaur also preferred to live in the coastal areas. The marine environment may have played a significant role in the evolution of hadrosaurs. (Scientific Reports, 2019; doi: 10.1038 / s41598-019-48607-1)

Source: Scientific Reports

- Daniel Albat