Arthropterygius is an extinct genus of ophthalmosaurid ichthyosaur which existed in Canada and Russia during the late Jurassic period. It contains the type speciesArthropterygius chrisorum, named in 2010 by Erin E. Maxwell. Arthropterygius is the generic replacement name for Ophthalmosaurus chrisorum, named in 1993 from fossils found on Melville Island in the Northwest Territories. It's fossils are the most complete of any ichthyosaur in the Canadian Arctic. A. chrisorum has several features that separate it from the genus Ophthalmosaurus, including a highly angled articulation between the radius and ulna and the humerus and a foramen for the internal carotid artery (a major artery that supplies blood to the brain) on the posterior surface of the basisphenoid. Maxwell 2010 found it to be the sister taxon of Caypullisaurus, an ophthalmosaurid from Argentina. However, many recent cladistic analyses found it to be the basalmost member of the Ophthalmosauridae.