Temporal range: Early Carboniferous– Late Permian
Artistic impression of a Orthacanthus hunting a Triodus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Euselachii
Order: Xenacanthida
Family: Orthacanthidae
Genus: Orthacanthus
Species: Orthacanthus arcuatus (Newberry, 1856)
+Orthacanthus cylindricus (Agassiz, 1843)
+Orthacanthus senckenbergianus

Orthacanthus is a genus of prehistoric freshwater shark that lived during the Paleozoic era. It was also an member of a group of ancient sharks called xenacanths, all of which were freshwater sharks with long fins down their backs and a spine at the start of the fin. It was the largest of the known xenacanths at 3 meters (10 feet) and 45 kg (100 lbs).

About 260 million years ago, Orthacanthus was the apex predator of freshwater swamps and bayous in Europe and North America. It owned a peculiar set of double-fanged teeth. They first appeared about 400 million years ago in the Devonian, and became extinct just before the Mesozoic, about 225 million years ago.

In Popular CultureEdit

  • Orthacanthus was featured in the Shark Week special Prehistoric Sharks, where it was labelled as the terror of permian swamps.
  • A set of jaws and teeth from Orthacanthus can be seen in the American Museum of Natural History in New York.
  • Orthacanthus appears in Jurassic World: The Game, where it is a cave creature that is obtained through VIP Membership.
  • A stylized Orthacantus is seen in The Land Before Time V: The Mysterious Island during the song Big Water.
  • It appears in the River Monsters episode Prehistoric Terrors alongside several other prehistoric fish.