Eugeneodontiformes

Helicoprion is an extinct genus of large shark-like cartilaginous fish that lived from the Early to the Middle Permian, about 290-270 million years ago. Helicoprion is a member of the Eugeneodontiformes, an extinct order of cartilaginous fish within the clade Holocephali, a group today represented only by chimaeras. It is also the type genus of the Helicoprionidae, a family of eugeneodonts characterised by distinctive tooth structures called tooth whorls. Helicoprion was first named in 1899 by Alexander Karpinsky on the basis of fossils discovered in Russia and Australia, the generic name mean

Edestus is an extinct genus of eugeneodontid holocephalian fish known from the Late Carboniferous (Pennsylvanian) of the United Kingdom, Russia, and the United States. Most remains consist of isolated curved blades or "whorls" that are studded with teeth, that in life were situated within the midline of the upper and lower jaws. Edestus is a Greek name derived from the word edeste (to devour), in reference to the aberrant quality and size of the species' teeth.

right|thumb|Helicoprion bessonovi, teeth at the front of the lower jaw (reversed for more natural position) 225px|thumb|Restoration of Romerodus ([[Caseodontidae)]]

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

Sarcoprion (from the Ancient Greek, "flesh saw") is an extinct genus of eugeneodont holocephalan from the Permian of Greenland. It possessed arching rows of connected teeth, termed tooth whorls, along the midline of its upper and lower jaws, as well as flattened, pavement-like teeth elsewhere in the mouth. It is distinguished from other members of its family by the presence of sharp, symphyseal teeth on both the upper and lower jaws. The tooth whorl on the lower jaw bore sharp, compact tooth crowns, while a row of backward facing, triangular teeth was present on the roof of the mouth. The pres

Fadenia is an extinct genus of eugeneodontid holocephalian chondrichthyan from the Carboniferous Period of Missouri (United States), the Permian period of Greenland, and the Early Triassic epoch of British Columbia, Canada (Sulphur Mountain Formation).

Parahelicoprion is an extinct genus of shark-like cartilaginous fish that lived during the Early Permian. The genus contains two species: P. clerci from the Arta Beds of the Ural Mountains of Russia, and P. mariosuarezi from the Copacabana Formation of Bolivia. Members of the genus possessed a row of large tooth crowns on the midline of the lower jaw, known as a tooth whorl. The characteristics of this whorl are unique to fishes of the order Eugeneodontida, and more specifically the family Helicoprionidae to which Parahelicoprion belongs. The genus name refers to Helicoprion, another eugeneodo

Caseodus is an extinct genus of eugeneodont from the Carboniferous of what is now the Midwestern United States, and potentially the Early Triassic of what is now British Columbia, Canada. The genus contains two Carboniferous species, C. basalis and C. eatoni, which are differentiated by the anatomy of their teeth but are otherwise identical. A third species, C. varidentis, is known from the Early Triassic Sulphur Mountain Formation, but due to its wildly different skull and tooth morphology it is questionable if it belongs in the genus. The genus name is in honor of paleoichthyologist Gerard C

The Edestidae are a poorly known, extinct family of shark-like eugeneodontid holocephalid cartilaginous fish.

Toxoprion (Ancient Greek for "bow saw") is an extinct genus of eugeneodont holocephalans whose fossils are found in marine strata from the Early Carboniferous until the Late Permian near Eureka, Nevada.

Campodus is an extinct genus of eugeneodont holocephalans from the Carboniferous. Likely one of the earliest and most basal caseodontoids, it can be characterized by its broad, ridge-ornamented crushing teeth made of various types of dentine. The type species, C. agassizianus, was originally described in 1844 based on a small number of teeth from the Namurian of Belgium.

Ornithoprion is an extinct genus of cartilaginous fish. The only species, O. hertwigi, lived during the Moscovian stage of the Pennsylvanian subperiod, which spanned from . Its fossils are preserved in black shales from what is now the Midwestern United States. The study of Ornithoprion was performed primarily via x-ray imaging, and at the time of its discovery it represented one of the best known holocephalans of the Paleozoic era. The classification of the genus has been the subject of debate due to its unique anatomy, and it is now placed in the order Eugeneodontiformes and the family Caseo