Orthacanthus
Another extinct freshwater shark, the Orthacanthus, lived in swamps and bayous approximately 225 million years ago. Scientists have also found fossils dated back to the Denovian era more than 400 million years ago. These sharks had long spines that extended from the back of the skull to the end of the body.
The Orthacanthus sharks were about 10 feet in length, and they looked more like a giant eel. The sharks were found in Europe and North America. Experts believe the sharks could have been cannibalistic because developing teeth were often found in the coprolites of adults.