''Chlamydoselachus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

s and the sole extant member of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Chlamydoselachidae, in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Hexanchiformes The Hexanchiformes Help:IPA/English, /hɛkˈsæŋkɪfɔːrmiːz/ are a primitive Order (biology), order of sharks, numbering just five extant species in two Family (biology), families, Chlamydoselachidae and Cow shark, Hexanchidae. Chlamydoselach ...

. It contains two extant and four extinct species. The most widely known species still surviving is the

frilled shark The frilled shark (''Chlamydoselachus anguineus''), also known as the lizard shark, is one of the two extant taxon, extant species of shark in the family (biology), family Chlamydoselachidae (the other is the southern African frilled shark, ''Ch ...

(''Chlamydoselachus anguineus''). It is known as a living fossil, along with ''Chlamydoselachus africana'', also known as the southern African frilled shark, which is only found along coastal areas of South Africa. The only two extant species of this genus are deep-sea creatures which are typically weakened in areas closer to the surface. While the two extant species are similar in external appearance, they differ internally. The earliest known fossil members of the genus are ''C. gracilis'' from

Angola Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...

and ''C. balli'' from

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

, both from the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

stage of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

. Formations with fossil ''Chlamydoselachus'' teeth are thought to be composed of deep-sea sediments, indicating that they have long inhabited deep-sea environments. Fossil ''Chlamydoselachus'' teeth closely resemble those of modern members. The largest species of the genus known to have existed is '' C. kamchaticus'' from the

Early Eocene In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

Kamchatka The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively. Immediately offshore along the Pacific ...

, Russia, whose teeth are about twice the size of modern frilled shark teeth. It is one of the largest frilled sharks known to have existed, with estimated body length of .

Species

* '' Chlamydoselachus africana'' Ebert & Compagno, 2009 (southern African frilled shark) * '' Chlamydoselachus anguineus'' Garman, 1884 (frilled shark) * †'' Chlamydoselachus balli'' Cappetta, Morrison & Adnet, 2019 * †'' Chlamydoselachus garmani'' Welton, 1983 * †'' Chlamydoselachus gracilis'' Antunes & Cappetta, 2002 * †'' Chlamydoselachus kamchaticus'' Malyshkina & Nazarkin, 2024 * †''

Chlamydoselachus lawleyi ''Chlamydoselachus'' is a genus of sharks and the sole extant member of the family Chlamydoselachidae, in the order Hexanchiformes. It contains two extant and four extinct species. The most widely known species still surviving is the frilled sha ...

'' Davis, 1887 * †''

Chlamydoselachus tobleri ''Chlamydoselachus'' is a genus of sharks and the sole extant member of the family Chlamydoselachidae, in the order Hexanchiformes. It contains two extant and four extinct species. The most widely known species still surviving is the frilled sha ...

'' Leriche, 1929 Chlamydoselachus lawleyi

Many other species formerly described in this genus were moved to the fossil genus ''

Rolfodon ''Rolfodon'' is an extinct genus of shark in the family Chlamydoselachidae. It is closely related to the extant frilled sharks in the genus '' Chlamydoselachus'', which it can be differentiated from by tooth morphology. It is named after late C ...

'' in 2019. ''Chlamydoselachus'' and ''Rolfodon'' can be distinguished from one another by their tooth morphologies. ''Rolfodon'' also survived the Cretaceous-Paleogene extinction event but went extinct during the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

References

Chlamydoselachidae Extant Campanian first appearances Shark genera Taxa named by Samuel Garman Campanian genus first appearances {{shark-stub