Prehistoric cartilaginous fish families

Helicoprionidae (sometimes referred to as Agassizodontidae) is an extinct family of holocephalans within the order Eugeneodontida. Members of the Helicoprionidae possessed a "whorl" of tooth crowns connected by a single root along the midline of the lower jaw. While historically considered elasmobranchs related sharks and rays, the closest living relatives of the Helicoprionidae and all other eugeneodonts are now thought to be the ratfishes. The anatomy of the tooth-whorls vary between taxa, with some possessing highly specialized, coiling spirals (such as those of the namesake genus Helicopri

Cladoselachidae is an extinct family of cartilaginous fishes closely related to, and possibly nested within, Symmoriiformes. They are characterized by having an elongated body with a spine in each of the two dorsal fins.

REDIRECT Xenacanthiformes

REDIRECT Hybodontiformes

REDIRECT Ctenacanthiformes

Symmoriidae is an extinct family of cartilaginous fish belonging to the order Symmoriiformes. Members of the family are known from the Devonian and Carboniferous periods.

Cardabiodontidae is an extinct family of lamniform sharks. Confirmed members of this family include Cardabiodon and Dwardius, both which are genera which existed in Australia, North America, and Europe during the Late Cretaceous period. It has been suggested that Parotodus could also belong to this family, but the authors that originally made this proposal expressed a weakening of rationale for it.

Anacoracidae is a family of extinct mackerel sharks that lived during the Cretaceous. It includes four valid genera: Nanocorax, Ptychocorax, Scindocorax, and Squalicorax. Two previously-included genera, Galeocorax and Pseudocorax, were reassigned to the family Pseudocoracidae.

REDIRECT Cretoxyrhina

Falcatidae is a family of Paleozoic cartilaginous fish belonging to the order Symmoriiformes. Members of this family include Falcatus, a small fish from the Bear Gulch Limestone of Montana. The family first appeared around the start of the Carboniferous, and there is some evidence that they survived well into the early Cretaceous, though its putative Cretaceous members were also argued to be more likely neoselachians.

REDIRECT Chondrenchelyiformes

Petalodontidae is an extinct family of marine cartilaginous fish related to the modern-day chimaeras, found in what is now the United States of America and Europe. With a very few exceptions, they are known entirely from teeth. All fossils range from the Carboniferous to the Permian, where they are presumed to have died out during the Permian/Triassic extinction event.