Both morphological and molecular evidence confirms that the order is a natural assemblage of fishes that diverged and evolved from a velifer ancestor sometime towards the end of the Mesozoic into the Eocene of the Cenozoic. Systematically, the group is of great interest because it represents the most primitive sister taxon to all higher groups of teloist fishes. From its origin to its subsequent evolution, the group underwent a distributional transition from shallow water and coastal forms to pelagic and mostly deep water fish, accompanied by a morphological transition from deep bodied fish to elongate forms exemplified most obviously by the icons of the group, the oarfish and its close relative, the ribbon fish.