larseni. Many of these specimens are preserved in three dimensions and partially in articulation; this is correlated with high abundance of organic elements in the sediments they were buried in, as well as a lack of invertebrates locally. Material belonging to four species of Arthropterygius, A. chrisorum, A. volgensis, A. lundi, and A. hoybergeti, has been reported from the Volga region of Russia, which gives the Volgian stage its name. Though very little is known or published about the fossils of these localities, fossils of a number of marine animals have been recovered, including species of the ichthyosaurs Nannopterygius and Undorosaurus. The presence of these taxa indicates that there was significant faunal exchange across the seas of Northern Europe during this time period. In addition to these three genera, fossils of the ichthyosaur Grendelius, the pliosaur Pliosaurus rossicus, and indeterminate remains belonging to a metriorhynchid, as well as a high diversity of ammonites including the large-bodied taxon Titanites, are also known from the Volgian-aged sediments of this region. A. thalassonotus hails from the Vaca Muerta Formation of the Neuquén Basin in Patagonia, Argentina. This is arguably one of the best marine reptile-bearing fossil sites of the Southern Hemisphere, and has revealed a great number of specimens of Late Jurassic marine reptiles. In addition to Arthropterygius, the ichthyosaurs Caypullisaurus bonapartei and Ophthalmosaurus sp. as well as two species of the genus Pliosaurus, P. patagonicus and P. almanzaensis, and a variety of marine turtles are known from the formation. It also features a uniquely diverse array of metriorhynchids, with species belonging to the genera Dakosaurus, Cricosaurus, Purranisaurus, and Geosaurus all having been reported. The extent to which the fauna reported from the Vaca Muerta Formation resembles that known from sites in the Northern Hemisphere, such as the Kimmeridge Clay, suggests that many marine reptile genera may have had near cosmopolitan distributions in the Late Jurassic. See also List of ichthyosaurs Timeline of ichthyosaur research References Fossil taxa described in 2010 Late Jurassic ichthyosaurs Fossils of Canada Extinct animals of Russia Paleontology in the Northwest Territories Ichthyosaurs of Europe Late Jurassic reptiles of Europe Tithonian life Fossils of Svalbard Agardhfjellet Formation Early Cretaceous ichthyosaurs Berriasian life Cretaceous Norway Ophthalmosauridae Ichthyosauromorph genera