Stethacanthus is a stethacanthid symmoriiform cartilaginous fish from the Late Devonian-Pennsylvanian of the United States of America, Russia, China, and Scotland. It was named in 1889 by John Strong Newberry. It was one of the most successful symmoriids to exist, lasting for more than a period.
Physiology[]
Stethacanthus resembled a shark, with a streamlined body, triangular pectoral fins, a crescent-shaped caudal fin, a mid-sized head, and large jaws. However, males of the genus had a large, stout, anvil-shaped dorsal fin protruding from their backs instead of a regular, triangular one, while females lacked a first dorsal fin altogether. Its body would have been covered in smooth skin, with a clump of pointed, bristle-like scales on the top of its head and dorsal fin.
Diet[]
Stethacanthus was a predator, preying on small fish, cephalopods, and brachiopods. Although its teeth were relatively small, they were still sharp, and were used to get a hold of any struggling prey.
Ecology[]
The function of Stethacanthus's unique, anvil-shaped dorsal fin has been open to debate for a long time, with many theories that emerged including attaching onto larger marine animals, as well as scaring predators its size by mimicking the mouth of a bigger fish. Today, the most widely accepted theory is that it was used for attracting mates, as studies have shown that it was only present in males. Along with well as this, its large size and bristle-like scales would have created a lot of drag during attempted bursts of speed, impeding the fish's movement; therefore, Stethacanthus would have been a slow swimmer. Like some modern sharks, Stethacanthus would have swam in coastal waters, feeding on any fish and cephalopods that shared the waters with it.
In popular culture[]
Stethacanthus was featured in the 1st episode of the 2003 documentary Chased by Sea Monsters, where it gets attracted to the smell of a dead Bothriolepis before getting scared off by a Dunkleosteus. It appeared again in a similar documentary, Walking with Monsters, where it chases a Hynerpeton right before a Hyneria shows up to snap it up.