A new genus and species of therizinosaurid dinosaur that lived during the Cretaceous period has been identified from the fossilized remains unearthed on Hokkaido, the northern island of Japan.
Dubbed Paralitherizinosaurus japonicus, the newly-discovered dinosaur roamed our planet during the Upper Cretaceous epoch, some 72 million years ago.
The ancient beast belonged to Therizinosauridae, a family of small to large, mainly herbivorous, theropod dinosaurs.
“Therizinosaurs have been found mainly from the Cretaceous deposits in Mongolia and China,” said Hokkaido University Museum paleontologist Yoshitsugu Kobayashi and colleagues.
“All of the Early Cretaceous species, except Falcarius, have been named from China so far, and two species are recovered from northern (Alxasaurus from the 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.”
“The Late Cretaceous therizinosaurs have been discovered from the Gobi Desert (Inner Mongolia of China and southern Mongolia) except for Nanshiungosaurus (Guangdong Province in the southeastern China along the Pacific).”
Fragmentary fossils of therizinosaurs are known from Japan, which was located at the eastern edge of the Asian continent during the Cretaceous period before the opening of the Japan Sea during the Miocene epoch.
One of these specimens, collected from the Osoushinai Formation in Nakagawa Town of Hokkaido Prefecture, was previously identified as a maniraptoran dinosaur, possibly therizinosaur, but its taxonomic status remained unresolved.
In the new study, Professor Kobayashi and co-authors 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.
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,” the authors concluded.
The study was published in the journal Scientific Reports.
Y. Kobayashi et al. 2022. New therizinosaurid dinosaur from the marine Osoushinai Formation (Upper Cretaceous, Japan) provides insight for function and evolution of therizinosaur claws. Sci Rep 12, 7207; doi: 10.1038/s41598-022-11063-5
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