Hexanchiformes

The Hexanchiformes are the order consisting of the most primitive types of sharks, and numbering just six extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens. The frilled shark, Chlamydoselachus anguineus, is very different from the cow sharks, and it has been proposed to be moved to its own order, Chlamydoselachiformes.

Hexanchiformes

The Hexanchiformes are the order consisting of the most primitive types of sharks, and numbering just six extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens. The frilled shark, Chlamydoselachus anguineus, is very different from the cow sharks, and it has been proposed to be moved to its own order, Chlamydoselachiformes.