These two species are very different from the other hexanchiform sharks, and it has recently been proposed that the two frilled sharks should be given their own order: Chlamydoselachiformes.
Additional extinct types are known from fossil teeth. The frilled shark was thought to be extinct itself; it was only discovered alive in Japanese waters in the 19th century. On January 21, 2007, a specimen was found alive off the coast of Japan and was brought to Awashima Marine Park in Shizuoka, where it died after a few hours. It was a 1.6 m (5.2 ft) long female found alive at the surface, perhaps there because of illness or weakness from the warm water.
