Halisaurinae. The analysis excluded the dubious Halisaurus onchognathus and the genus Pluridens. Species Two species are known, P. ortliebi and P. ponpetelegans, the latter from the oldest Maastrichtian beds located in Hokkaido, Japan. The skull of the latter species is thought to be around 50 cm long. The etymology of P. ponpetelegans derives from the words "ponpet", which means "creek" in Ainu (language of the indigenous peoples of Hokkaido), and "elegans", Latin for "elegant", referencing the exceptional preservation of the holotype specimen of the species and the clean Pankerusano-sawa Creek where the fossil was discovered. P. ortliebi and P. ponpetelgans can be distinguished from each other by several fossil characters. For instance, the prefrontal postnarial medial lamina are smaller in P. ponpetelgans than in P. ortliebi and the development of prefrontal supraorbital tuberosity is minimal compared to P. ortliebi. In P. ponpetelgans the median dorsal ridge of the frontal becomes weak posterior to the orbits, which does not occur in P. ortliebi. References Russellosaurins Mosasaurs of Europe Fossil taxa described in 1889 Fossils of Japan Taxa named by Louis Dollo Fossils of Belgium Mosasaurs of Asia Maastrichtian genera