Orthacanthus is an extinct freshwater shark belonging to the family Xenacanthida. Members of the genus had a long spine growing from the back of their skull and a very long dorsal fin, which ran all along its back, making the shark look more like an eel. 260 million years ago, Orthacanthus hunted the Carboniferous and Permian swamps and bayous of Europe and North America, and was the apex predator of its environment. At 3 m (10 ft) long, Orthacanthus was a hunter of fish, amphibians and perhaps reptiles and synapsid protomammals that came to drink at the water's edge or that risked a swim through the swamps. Orthacanthus and the rest of its kin would rule the freshwater environments until 225 million years ago, when the early representatives of the dinosaurs began their rise to dominance. The reason for this shark's extinction is still a mystery, but may be tied to a changing environment and competition from other species of freshwater sharks.
Cannibalism[]
The discovery of Orthacanthus coprolites from Canada by Aodhan O' Gogain et al revealed that in times of hardship, Orthacanthus was likely cannibalistic, as teeth from juvenile Orthacanthus were found within the coprolites of adults. During times such as droughts, the adult sharks would eat their pups, a strategy used today by many types of animal, including other sharks. This may, as climates changed, also have been a potential factor in the extinction of Orthacanthus, as cannibalism of young would create genetic bottlenecks and eventually, when a population was small enough, lead to inbreeding and eventual extinction.
In Popular Culture[]
Orthacanthus appears in an episode of Shark Week called Prehistoric Sharks, in which it is called "The terror of Permian swamps". In the third episode of Season 7 episode of River Monsters, Jeremy Wade examines this shark, labelled only as a Xenacanth and by its moniker of "eel shark".