''Listracanthus'' is a genus of extinct

chondrichthyan Chondrichthyes (; ) is a class that contains the cartilaginous fishes that have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fishes'', which have skeletons primarily composed of bone tissue. ...

with uncertain affinities. Species of ''Listracanthus'' are known primarily from their tremendous, feather-like

denticle A denticle is any small tooth-like or bristle-like structure. "Denticle" may refer to: * Denticle (tooth feature), serrations on the teeth of dinosaurs, lizards, sharks, and mammals * Dermal denticles or placoid scales, in cartilaginous fishes * ...

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

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

The appearance of these sharks are largely unknown. However, author and illustrator

Ray Troll Ray Troll (born March 4, 1954) is an American artist based in Ketchikan, Alaska. He is best known for his scientifically accurate and often humorous artwork. His most well-known design is "Spawn Till You Die", which has appeared in many places inc ...

mentions in his book, ''Sharkabet'', about how paleontologist Rainer Zangerl 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. Martill et al., (2014) created the genus '' Acanthorhachis'' for the species formerly known as ''"Listracanthus" spinatus'' (Bolton, 1896). They also erected the family Listracanthidae to encompass the two genera.

References

Prehistoric fish of North America Prehistoric cartilaginous fish genera Carboniferous cartilaginous fish Permian cartilaginous fish Triassic cartilaginous fish Pennsylvanian first appearances Early Triassic extinctions {{paleo-cartilaginous-fish-stub