''Palaeospinax'' is an extinct genus of synechodontiform cartilaginous fish. Although several species have been described, the genus is considered ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

'' because the type-specimen of the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, ''Palaeospinax priscus'', from the Late Triassic-Early Jurassic of Europe lacks appropriate diagnostic characters to define the genus. Other species originally described as ''

Synechodus ''Synechodus'' is an extinct genus of shark belonging to the family Palaeospinacidae and order Synechodontiformes. It is known from 16 species primarily spanning from the Late Triassic to Paleocene The Paleocene ( ), or Palaeocene, is a geol ...

'' were transferred to the genus '' Palidiplospinax''.

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Further reading