A new Barremian (Early Cretaceous) ichthyosaur from western Russia

A new ophthalmosaurid ichthyosaur, Sveltonectes insolitus gen. et sp. nov., is described from a sub-complete and three-dimensionally preserved specimen from the late Barremian of western Russia. This new taxon is supported by 11 cranial, dental, and postcranial autapomorphies, and is also characterized by features previously considered as autapomorphic for some other Ophthalmosauridae, such as a processus narialis on the prefrontal and relatively long hindfins with pre- and postaxial accessory digits. We conducted a new phylogenetic analysis of Thunnosauria, which supports a ‘Stenopterygius-origin’ for Ophthalmosauridae. Sveltonectes is regarded as the sister taxon of Aegirosaurus, which shares a similar skull roof construction. Contrary to most other Cretaceous ichthyosaurs, Sveltonectes is characterized by delicate and sharply pointed teeth, confirming that the Ophthalmosauridae were ecologically highly diversified during the Early Cretaceou