Ceratopsians were a group of plant-eating, horned dinosaurs that originated in East Asia in the early Cretaceous period. They migrated to North America, where they flourished in the late Cretaceous period.
According to the National Museum of Nature and Science in Tokyo, there had been a previous discovery of neoceratops, a more primitive dinosaur, in Hyogo Prefecture. This is the second discovery of fossils belonging to horned dinosaurs and the first discovery of a ceratopsian fossil in the country.
There have only been two other discoveries of ceratops fossils in Asia, in China and Uzbekistan. This finding will be reported at a meeting of the Paleontological Society of Japan in Kumamoto Prefecture in June.
The tooth fossil constitutes a joint of a dental root measuring 12.1 millimeters long, 8.6 millimeters high and 3.7 millimeters thick. It was discovered during a survey conducted by the board of education in November 2011.
As ceratopsians were believed to bite off vegetation using their mouth like a pair of scissors, they were the only dinosaurs to have two dental roots.
The discovery's shape helped its identification. In particular, it nearly matched triceratops fossils, which have been discovered mainly in North America.