A fossilized skull of a nodosaur family unearthed in Hokkaido, Japan over two decades ago has been identified as a new genus and species.
Nipponoperta ezoensis. Image credits: total dino /CC BY 4.0.
The newly discovered dinosaur species lived during the Late Cretaceous Period, around 96 to 94 million years ago.
Named Nipponoperta ezoensis, it is the first ankylosaurus officially named in Japan, and only the second Asian member of its subfamily. Nodosauridae is only known from body bones, not skull material.
“Ankylosauridae, now known as Euankylosauridae, are widely found in Cretaceous deposits. They are divided into nodosaurids and ankylosaurids,” explained paleontologists from Hokkaido University, including Shunpei Oyabu and his colleagues.
“Nodosaurids are more commonly found in marine sediments than ankylosaurids. Their distribution is mainly in mid-Cretaceous deposits of Japan and China, with lower abundance compared to North America and Europe.”
The skull parts of Nipponoperta ezoensis were found in Upper Cretaceous sediments in Yubari City, Hokkaido.
Initial identification of the fossil as a nodosaur led to further taxonomic study by Oyabu and researchers from Japan, Canada, and the US.
Using CT scans, researchers reconstructed previously unseen parts of the skull, revealing unique features and placing Nipponoperta ezoensis among nodosaurids from North America and Europe.
The study, published in Cretaceous Research, sheds light on the dispersal patterns and habitat preferences of these ancient dinosaurs.
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Susumu Oyabu others. A new nodosaurid ankylosaur (Dinosauridae: Ornithischian order) discovered from the Upper Cretaceous Hikagenosawa Formation in Japan reveals the dispersal pattern of Asian nodosaurids. Cretaceous Research published online on August 21, 2026. doi: 10.1016/j.cretres.2026.106477
Source: www.sci.news
