These 81-million-year-old teeth are the first bit of evidence of Japan's largest ever dinosaur

Scientists in Japan have unearthed 81-million-year-old teeth that are the first evidence to be found in the country of a large tyrannosaurid dinosaur.

Researchers from Fukui Prefectural Dinosaur Museum (FPDM) and Nagasaki City discovered the theropod dinosaur teeth from the late Cretaceous period on the western coast area of the Nagasaki Penisula.

The two on the left are from a large species of tyrannosaurid measuring up to 10 metres and the right one is the tooth of another smaller theropod dinosaur. The fossil on the far left has nearly the complete crown preserved and measures 7.2cm with a root making it 8.2cm.

Kazunori Miyati, chief researcher of the museum, said: “The large size, the shape of cross section, and the age suggest the teeth are of large species of tyrannosaurid, comparable to those of Tyrannosaur in North America, Tarbosaurus and Zuchengtyranus in Asia.

“Although the middle tyrannosaurid tooth is incomplete, it is even larger if it is complete.

“The teeth are the first record of large tyrannosaurid species in Japan and are significant on the paleobiogeography and age of tyrannosaurid dinosaurs.

“In the past, many fossils of Cretaceous vertebrates including dinosaurs were found from Nagasaki (foot bones of hadrosaurid dinosaurs, teeth of ankylosaur dinosaur and smaller theropod dinosaurs, bones of pterosaur and turtles).”

Theropod dinosaurs were a group of saurischian dinosaurs that were originally carnivorous, but some evolved to not eat meat.

Paleobiogeography is the study of where dinosaurs lived and when.