A Turonian Polycotylid Plesiosaur (Reptilia: Sauropterygia) from Obira Town, Hokkaido, and Its Biostratigraphic and Paleoecological Significance Sato, Tamaki and Hanai, Tomoya and Hayashi, Shoji and Nishimura, Tomohiro, Paleontological Research, 22, 265-278 (2018), DOI:http://dx.doi.org/10.2517/2017PR024