| Yamatosaurus | |
|---|---|
 | |
| Holotype dentary seen from four angles | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Family: | †Hadrosauridae |
| Genus: | †Yamatosaurus Kobayashiet al. 2021 |
| Species: | †Y. izanagii |
| Binomial name | |
| †Yamatosaurus izanagii Kobayashiet al. 2021 | |
Yamatosaurus (meaning "Yamato reptile") is agenus of basalhadrosaurid from theLate Cretaceous (Maastrichtian)-agedKita-Ama Formation ofAwaji Island,Japan. The genus contains a singlespecies,Yamatosaurus izanagii.[1]
TheholotypeMNHAH D1-033516, consisting of part of the right lowerjaw, twelveteeth, fourcervical vertebrae, threecervical ribs, a partial rightcoracoid and a posteriorcaudal vertebra, was discovered onAwaji Island inJapan in May 2004 by Shingo Kishimoto. In 2005, the find was reported in the scientific literature.[2] Kishimoto in 2013 donated the holotype to Japan's Museum of Nature and Human Activities in theHyogo Prefecture, where the fossils were prepared by Kazumi Wada, Tomomi Ikeda and Chisato Ota to be described in 2021. The speciesYamatosaurus izanagii was named in 2021 byYoshitsugu Kobayashi, Ryuji Takasaki, Katsuhiro Kubota and Anthony Ricardo Fiorillo. The fossils were found in dark greymudstones within the upper partKita-Ama Formation, which was deposited in marine conditions in distalturbidite facies on the edge of thecontinental slope in anintra-arc basin. The sediments date tosubchron 32.1r28, corresponding to the earlyMaastrichtian stage of the Late Cretaceous, around 71.94–71.69 million years ago, making it roughly contemporaneous with fellow Japanese hadrosaurKamuysaurus.[1]
The generic name,Yamatosaurus, refers toYamatai, also known as Yamato, an ancient region in Japan ruled by theYamato Kingdom, while the specific name,Y. izanagii, refers to the deityIzanagi, who created eight islands in Yamato:Awaji Island (where the holotype was discovered)Shikoku,Oki,Kyushu,Iki,Tsushima,Sado andHonshu.
Yamatosaurus is a basal hadrosaurid, more derived thanHadrosaurus but less thanSaurolophinae+Lambeosaurinae. Its presence, along with those ofPlesiohadros andTanius, suggests East Asia may have served as a refuge for basal hadrosaurs in the Late Cretaceous. However, it was also contemporaneous with the more derivedKamuysaurus, suggesting some level of provinciality.
