The shark order Hexanchiformes (in a broad sense, not only comprising the cow sharks, but also including the frilled sharks, Chlamydoselachidae) is often considered the most primitive of extant sharks, since they share some features with Paleozoic and early-Mesozoic shark groups as the Cladoselachiformes. Thus, it is interesting to see how far back the fossil record of this order reaches.
Family Chlamydoselachidae SpeciesLower CretaceousUpper CretaceousPaleoceneEoceneOligoceneMiocenePliocenePleistoceneHoloceneExtantBVHBAACTCSCMDSTYLBPRCABLSTMZPGLMUChlamydoselachus thomsoniRichter & Ward (1990 ): "Fish remains from the Santa Marta Formation (Late Cretaceous) of James Ross Island, Antarctica." Antarct Sci 2 (1) : 71 [Zoological Record Volume 126]Chlamydoselachus gracilisAntunes & Cappetta (2002): [Selachians from the Cretaceous (Albian-Maastrichtian) from Angola.] Palaeontogr Abt A Palaeozool-Stratigr 264 (5-6) April: 107 [Zoological Record Volume 138]Chlamydoselachus goliathProteothrinax baumgartneriChlamydoselachus fiedleriChlamydoselachus tobleri.Chlamydoselachus bracheriChlamydoselachus lawleyiChlamydoselachus anguineus
Family Hexanchidae SpeciesLower CretaceousUpper CretaceousPaleoceneEoceneOligoceneMiocenePliocenePleistoceneHoloceneExtantBVHBAACTCSCMDSTYLBPRCABLSTMZPGLMUHeptranchias howellii.Heptranchias ezoensisHeptranchias tenuidensHeptranchias perlo..------
GenusSpeciesEarly JurassicMiddle JurassicUpper JurassicLower CretaceousUpper CretaceousPaleoceneEoceneOligoceneMiocenePliocenePleistoceneHoloceneExtantHSPTABBCOKTBVHBAACTCSCMDSTYLBPRCABLSTMZPGLMUHexanchusarzoensismicrodon “agassizii”....graciliscollinsonaehookeriagassizi.griseus.nakamurai “vitulus” griseus “andersoni” “gigas".Notidanoides-.Notidanodonlanceolatus.-antarctidentatuspectinatusbrotzeni”loozi”Notorynchus“Notidanus” aptiensis”“Notidanus” intermedius“Notidanus” lawleyi“Notidanus” munsteri“Notidanus” cepedianus “primigenius” “kempi”...“Notidanus” serratissimus“Notidanus” serratus
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