Satsuma-utsunomiya-ryu

"Satsuma-utsunomiya-ryu" is an undescribed plesiosaur known from Kyushu, Japan. This nickname is named after the former province name of the discovery site and the discoverer, Satoshi Utsunomiya. It is the oldest known elasmosaurid plesiosaur fossil in East Asia, dating back to approximately 100 million years ago. It is permanently exhibited at the Kagoshima Prefectural Museum.

Furthermore, the world's first plesiosaur "pellet" was found in the throat area.

Description
The specimen of Satsuma-utsunomiya-ryu (SU01) was discovered from the Hegushi Formation of the Goshoura Group (lower Cenomanian, Upper Cretaceous) of Shishijima Island, Kagoshima Prefecture in 2004 by Satoshi Utsunomiya. He worked on cleaning, research and publication later. Since another findings of plesiosaur fossils are mostly from Hokkaido and Tohoku (like Futabasaurus and "Hobetsu-araki-ryu"), it is significant as the first discovery of plesiosaur fossil from Kyushu.

The known materials include the mandible, tongue bone (first record from Japan), fragments of the skull, 40 cervical vertebrae, and a limb bone. This specimen was possibly a juvenile, based on the structure of the vertebrae. Features like ornamentation on tooth surfaces and the structure of cervical vertebrae, suggest that Satsuma-unomiya-ryu belongs to the Elasmosauridae and may represent a new species. It is the oldest member of the family from East Asia and it offers crucial insights into the presence of elasmosaurid in the northwestern Pacific during the early Late Cretaceous. In 2021, Ustunomiya and Yasuhisa Nakajima reported presence of "pellet" around its throat region.