A team of international scientists has identified a new species of “duckbill” dinosaur, also known as hadrosaurus, on an island in southern Japan. Yamatosaurus izanagii, the fossil brings new evidence about the creature’s migration, further suggesting that these herbivores migrated from Asia to North America and not the other way around.
The discovery also proves that these giant creatures have evolved to the point of stopping from walking upright to walking on all fours. Hadrosaurs, which are known to have wide, flat snouts, are the most commonly found out there. They lived in the Upper Cretaceous period, over 65 million years ago, and their fossils have already been found in North America, Africa, Asia and Europe.
With hundreds of well-spaced teeth on the cheeks, Hadrosaurs have been highly adapted to chew vegetation for food. If the teeth wore and fell, new teeth were born individually, or a new dental row appeared to replace the old one. The Yamatosaurus discovered in Japan, according to paleontologists, appears to have evolved to be able to chew different types of vegetation compared to other Hadrosaurs.
Another difference of the new dinosaur is the development of its shoulders and forelimbs, which prove the change from biped to quadruped. Part of the Yamatosaurus was found in 2004 in a sediment layer approximately 72 to 71 million years ago, in a cement quarry on the island of Awaji. The fossil had a preserved lower jaw, as well as teeth, neck and tail vertebrae, and shoulder bone. The material remained in a museum until it was studied by scientists.
Yamatosaurus is the second new species of Hadrosaurus identified by the same scientists in Japan. In 2019, the pair found the largest dinosaur skeleton in the country, also a Hadrosaurus, this one named Kamuysaurus. Its fossils were found on the island of Hokkaido, in the north of the country.
“These are the first dinosaurs discovered in Japan from the end of the Cretaceous Period. Until now, we had no idea which dinosaurs lived in the country until the end of the era of dinosaurs,” says Yoshitsugu Kobayashi, a researcher who has been studying the discovery.