New dinosaur species discovered from fossils unearthed in Japan

Scientists have identified a new species and genus of mostly plant-eating dinosaurs that lived about 72 million years ago based on fossils unearthed from Hokkaido, the northern island of Japan.

The new dinosaur, named Paralitherizinosaurus japonicus, roamed the Earth during the Upper Cretaceous epoch about 72 million years ago, according to the study published in the journal Scientific Reports.

It belonged to a family of small to large, mainly herbivorous theropod dinosaurs called Therizinosauridae, say scientists including those from Hokkaido University in Japan.

“Therizinosaurs have been found mainly from the Cretaceous deposits in Mongolia and China,” researchers said, adding that except the dinosaur Falcariusm, all of the Early Cretaceous species have been named from China so far.

Two other species, they said, were recovered from northern (Alxasaurus from Inner Mongolia) and northwestern (Suzhousaurus from Gansu Province) regions.

“Other Chinese species (Jianchangosaurus, Beipiaosaurus, and Lingyuanosaurus) were recovered from the Jehol Group in the Liaoning Province of China, located in the eastern part of the country,” researchers added.

While fragmentary fossils of therizinosaurs are known from Japan, scientists said the taxonomic status of these dinosaurs remained unresolved.

They said such fossils were located at the eastern edge of the Asian continent during the Cretaceous period before the opening of the Japan Sea during the Miocene epoch, which spanned from about 23 million years to 5.3 million years ago.

One such specimen, collected from the Osoushinai Formation in Nakagawa Town of Hokkaido Prefecture, was previously identified as a maniraptoran dinosaur, and a potential therizinosaur, scientists said.

In the new study, researchers re-examined the specimen and identified it as a new therizinosaurid species.

“Paralitherizinosaurus japonicus is the third therizinosaur specimen from Japan, following a single tooth from Honshu Island and a partial braincase, teeth, and humerus from Kyushu Island,” they said.

Scientists said the dinosaur belonged to a new taxon based on fresh evidence that it had distinct characteristics in its limbs and claws.

“Our study demonstrates that it is a new taxon, Paralitherizinosaurus japonicus gen. et sp. nov., because it shows a unique combination of characters in the metacarpal I and unguals,” researchers wrote in the study.

They said the species is also the youngest therizinosaur from Japan and the first recovered from the marine deposits in Asia.

“This suggests a long temporal existence of therizinosaurs at the eastern edge of the Asian continent and adaptation of therizinosaurs to coastal environments,” researchers added.