Kamuysaurus
Kamuysaurus is a plant-eating hadrosaurid dinosaur from the Late Cretaceous period, about 72.1 to 70.6 million years ago. It lived in what is now Hokkaido, Japan, in marine rocks of the Yezo Group (Hakobuchi Formation).
In 2003, a tail was found by amateur paleontologist Yoshiyuki Horita. In 2013–2014, a nearly complete skeleton was uncovered by teams from the Hobetsu Museum and Hokkaido University Museum. The skeleton was nicknamed Mukawaryu, the “Dragon of Mukawa.” In 2019, scientists named it Kamuysaurus japonicus. The name Kamuysaurus comes from kamuy, a deity in the Ainu language, and japonicus means “Japanese.”
The holotype is specimen HMG-1219, found in the Hakobuchi Formation dating to the early Maastrichtian. It includes a nearly complete skeleton with a skull, missing only the snout, some sacral vertebrae, and some toe bones. It represents an adult at least nine years old and is one of the most complete dinosaur skeletons found in Japan.
The bones were found on a 7 by 4 meter surface and were partly preserved and articulated, though damaged by erosion. Kamuysaurus was about 8 meters long and weighed roughly 4 to 5.3 tonnes, depending on whether it stood on two legs or walked on four.
Three unique features help identify Kamuysaurus: a very low notch on the quadrate bone (the jaw joint area) that is unusual for hadrosaurids; a lower jaw bone (surangular) with only a short ascending branch that does not reach the coronoid process; and the neural spines on the sixth to thirteenth back vertebrae that tilt forward.
This page was last edited on 2 February 2026, at 18:53 (CET).