Paleogene Sea Snakes from the Eastern Part of Tethys

Nessovophis tamdy gen. et sp. nov. (Nigerophiidae, middle Eocene, Bartonian), Nessovophis zhylga sp. nov. (early Eocene, Ypresian), Palaeophis ferganicus sp. nov. (early Eocene, Ypresian), Palaeophis udovichenkoi sp. nov. (middle – ?late Eocene, Bartonian – ?Priabonian), Palaeophis nessovi sp. nov. (late Eocene, Priabonian), Palaeophis sp. (middle Eocene, Bartonian), and Pterosphenus muruntau sp. nov. (middle Eocene, Bartonian) are described and Vialovophis zhylan Nessov, 1984 (?latest Paleocene) is redescribed on the basis of 45 isolated vertebrae from 8 localities in Kazakhstan, Tajikistan, Kirghizia, Uzbekistan, and Ukraine. Phylogenetic analysis of 8 Cretaceous-Paleogene taxa of sea snakes reveals two monophyletic groups: Palaeophiidae (Palaeophis and Pterosphenus) and Nigerophiidae (Nigerophis, Woutersophis, and Nessovophis).