''Listracanthus'' is a genus of extinct

chondrichthyan Chondrichthyes (; ) is a class (biology), class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which ...

with uncertain affinities. Species of ''Listracanthus'' are known primarily from their tremendous, feather-like denticles, which range up to four inches in length. The denticles had a large main spine, from which secondary spines emanate from the sides, like the barbs of a feather or a comb. ''Listracanthus'' first appeared in late

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

strata in North America, and eventually disappear from the fossil record some time during the Early

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

. The appearance of these sharks are largely unknown. However, author and illustrator Ray Troll recounts an anecdote in his book, ''Sharkabet'', about how paleontologist Rainer Zangerl reportedly once discovered a large shale slab containing a long, eel-like fish covered in long, spine-like denticles characteristic of the genus, only to have it dry out and crumble into dust. As such, according to Zangerl's account, Troll reconstructs ''Listracanthus'' as resembling a tremendous, fiercely bristled frill shark. However, other authors have noted that ''Listracanthus''-like denticles have been found associated with the remains of Menaspiformes like '' Deltoptychius'' (which do not have eel-like bodies), and have suggested that ''Listracanthus'' is a member of this group. Martill et al., (2014) created the genus ''

Acanthorhachis ''Acanthorhachis'' is an enigmatic extinct genus of chondrichthyan from the Carboniferous period. Its name is derived from the Greek word ''acanthos'' meaning "spine" and the Greek suffix for spine, -''rhachis''. This is due to the spine-like de ...

'' for the species formerly known as ''"Listracanthus" spinatus'' (Bolton, 1896). They also erected the family

Listracanthidae Listracanthidae is a proposed family of extinct cartilaginous fish. It currently includes the genera '' Listracanthus'' and '' Acanthorhachis''. This clade is likely included within Elasmobranchii, but its placement within it is uncertain. Both g ...

to encompass the two genera.

References

{{Taxonbar, from=Q620477 Prehistoric fish of North America Prehistoric cartilaginous fish genera Carboniferous cartilaginous fish Permian cartilaginous fish Triassic cartilaginous fish Pennsylvanian first appearances Early Triassic extinctions