Not only was Orthacanthus very similar to the smaller Xenacanthus, it also has a similar temporal range in the fossil record. The two sharks probably coexisted with only the minimum of competition between the two. This is because at only one meter long, Xenacanthus could operate in waters that were too small or densely overgrown to support a three meter long predator like Orthacanthus.
As the larger of the two, Orthacanthus would have specialised in larger and more powerful prey that it would have seized with its double fanged teeth. The overall eel like body morph of Orthacanthus is a reflection of its habitat. Rather than being a pelagic open seas predator, Orthacanthus hunted in freshwater swamps and waterways that would have been densely overgrown in areas. By having a long body with short fins Orthacanthus could navigate these waters without getting stuck in submerged debris and vegetation. It's possible that Orthacanthus may have used ambush tactics like lurking within the submerged debris and plants waiting for prey to pass by.
The spike that rises up from the back of the head of Orthacanthus seems to have been a defensive feature to stop other predators from clamping their jaws onto its head. These exact predators may still be unknown to science but they may have been other fish like Hyneria, or large amphibian tetrapods.
Orthacanthus has been suggested to play 8 roles. Click below to see other actors suggested for each role, and vote for who you think would play the role best.
