Hydrorion – a new plesiosaur from Germany

The most recent issue of the ‘Palaeontology’ (Vol 49, Part 3) features an article by Franziska Grossman on the plesiosauroids from the Jurassic Posidonia Shale in Germany. Grossman describes the skulls of two genera, Seeleyosaurus guilelmiimperatoris (a tongue-twister of a taxon! – formerly Plesiosaurus guilelmiimperatoris) and introduces a new genus Hydrorion brachypterygius (formerly Plesiosaurus brachypterygius). Interestingly, Grossman analyses the holotype of ‘Plesiopterys’, a genus erected by O’Keefe (2004), and identifies it as a juvenile of Seeleyosaurus. Another major consequence of this paper is the removal of these species from Plesiosaurus, a genus which now contains only one valid species: P. dolichodeirus.