A species of duck-billed dinosaur has been discovered in Japan which rewrites what we know about how hadrosaurs spread around the world.
It was previously believed hadrosaurs — known for their broad, flat snouts — migrated from North America to Asia before going extinct 66million years ago.
But the fossilised remains of a never-before-seen species dubbed Yamatosaurus izanagii reveals the route was in fact the other way round.
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The new discovery of fossilised remains of a never-before-seen dinosaur species dubbed Yamatosaurus izanagii (pictured, artist’s impression) reveals the route of migration for hadrosaurs was from Asia to America
Hadrosaurs had rows of flat teeth close together which were used to grind up and chew various forms of vegetation.
When these teeth were worn down to a nub or fell out, they were replaced by fresh dentition which lay in reserve in the gums.
This ability means duck-billed reptiles were able to thrive across the world and fossils have been discovered in Asia, including Japan, as well as Europe, Africa and North America.
However, understanding how the vegetarian dinosaurs emerged and spread across the world has proven difficult in the past.
Hadrosaurs lived during the Cretaceous period, the most modern dinosaur period when they went extinct due to a huge meteorite impact 66million years ago.
But Yamatosaurus izanagii is believed to be around 72million years old.
Analysis of the new species revealed it looked different to other hadrosaurs, with notable differences with the teeth and limbs.
For example, instead of having several replacement teeth for each dental position in its mouth, it had only one backup for certain teeth.
It was also likely bipedal, plodding on two legs instead of four.
Pictured, an artist’s impression of another duck-billed dinosaur that lived 80 million years ago and was discovered in Texas
A new species of hadrosaur has been discovered on the Japanese island of Awaji (pictured)
These indicate that the Japanese duck-billed dinosaur, which was first found in 2004, is an early hadrosaur which represents a transitional point in the evolution of the plant-eating giants.
Dr Anthony Fiorillo of Southern Methodist University in the US, co-author of the study, believes dinosaurs in Asia likely spread to the Americas via the Bering Land Bridge.
The dinosaur is the second new species of hadrosaur discovered in Japan, which was attached to mainland Asia at the time of the dinosaurs.
‘These are the first dinosaurs discovered in Japan from the late Cretaceous period,’ says Yoshitsugu Kobayashi, professor at Hokkaido University Museum and co-author of the study.
‘Until now, we had no idea what dinosaurs lived in Japan at the end of the dinosaur age.
‘The discovery of these Japanese dinosaurs will help us to fill a piece of our bigger vision of how dinosaurs migrated between these two continents.’
The findings are published in the journal Scientific Reports.
