Kingdom Animalia
Phylum Chordata
Class Chondrichthyes
Subclass Holocephali
Order Symmoriida
Family Stethacanthidae
Genus Stethacanthus
1st Species Stethacanthus altonensis
2nd Species Stethacanthus productus
3rd Species Stethacanthus praecursor
4th Species Stethacanthus mirabilis
Other attributes
Time Range 382.7-323.2 mya
Location United States of America, Russia, China, Scotland
Name Meaning Chest spine
Physical Dimensions 70 centimeters long
Dietary Classification Carnivore
Stethacanthus is a stethacanthid symmoriid 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.


Stethacanthus resembled a shark, with a torpedo-shaped body, triangular pectoral fins, a crescent-shaped caudal fin, a mid-sized head, and large jaws. However, it had one major defining characteristic: instead of a regular, triangular dorsal fin, it had an anvil-shaped dorsal fin with bristle-like scales on top of it. Its body would have been covered in scaly skin.


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.


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 cultureEdit

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.

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