A new genus and species of hadrosaur (also known as duck-billed dinosaurs) has been unearthed in Japan’s Awaji Island. An international team of paleontologists identified the new species as Yamatosaurus izanagii.
The partial skeleton of the new species was found back in 2004 by an amateur fossil hunter. The bones included teeth, lower jaw, neck, vertebrae, shoulder bone, and tail vertebra. The remains were unearthed in an ancient layer of sediment in a cement quarry on the island that dates back about 71-72 million years. They were then brought to Japan’s Museum of Nature and Human Activities in the Hyogo Prefecture where they were analyzed in further detail.
The most well-known feature of a Hadrosaur is its wide, flat snout which is why it’s commonly known as a duck-billed dinosaur. It was an herbivore that walked the Earth from 75 to 65 million years ago during the Late Cretaceous Period. On average, they measured about 30 feet in length and weighed about 3 tons. (The estimated length of the Yamatosaurus izanagii would have been approximately 8 meters in length (26 feet) and weighed between 4 and 6 tons.) These dinosaurs lived in North America, Africa, Europe, and Asia.
Hadrosaurs had hundreds of teeth that were packed into dental batteries and when one tooth would fall out, another would replace it. It is also believed that they had cheeks that helped them keep their food in their mouth. However, the dental structure in the Yamatosaurus species was quite different as it only had one functional tooth in numerous battery positions with no branched ridges which indicates that it ate different plants than other hadrosaurs.
What’s even more interesting than finding an entirely new genus and species is that the discovery represents the evolutionary period when these dinosaurs transformed from being bipedal to quadrupedal. A picture of what the Yamatosaurus izanagii would have looked like can be seen here.
Furthermore, it has rewritten the migration journey that these dinosaurs made millions of years ago. It is now believed that hadrosaurs migrated from Asia to North America (instead of the other way around). When hadrosaurs lived on Awaji, the island was still attached to the eastern part of Asia. The dinosaurs were believed to have traveled across the Bering Land Bridge in order to get from Asia to Alaska and then onto other parts of North America. (A picture of the Yamatosaurus izanagii fossils can be seen here.)
The Yamatosaurus izanagii skeleton is expected to be put on display at a Japanese museum in the near future. The research was published in Scientific Reports where it can be read in full.
Another interesting fact is that the Yamatosaurus izanagii is actually the second hadrosaurid species that has been discovered in Japan. In 2019, the largest ever dinosaur skeleton was unearthed on the island of Hokkaido. The remains belonged to another type of hadrosaurid called Kamuysaurus.