456 genera · Mosasauridae · Sauropterygia · Ichthyosauria
This section brings together three distinct lineages of Mesozoic marine reptiles: Mosasauridae (giant marine lizards of the Late Cretaceous), Sauropterygia (plesiosaurs and pliosaurs, Triassic–Cretaceous) and Ichthyosauria (streamlined vertebrates, Triassic–Cretaceous). These groups are phylogenetically unrelated and each returned to the sea independently.
