Dinosaurs & Prehistory - Prehistoric marine predators - Helicoprion - Prehistoric fish - Permian - Prehistoric marine life
Where was Helicoprion's famous spiral tooth whorl located?
Correct!
Helicoprion was an extraordinary cartilaginous fish that lived during the Permian. It is famous for a spirally coiled row of teeth known as a tooth whorl. Because for a long time these tooth whorls were virtually the only fossils known, scientists puzzled for more than a century over where they were positioned in the animal. Earlier reconstructions placed the whorl on the outside of the snout, for example, or even on other parts of the body. The mystery was not resolved until a CT study of an exceptionally well-preserved fossil was published in 2013: the tooth whorl occupied the entire lower jaw arch and was supported along the lower jaw's midline. The functional tooth crowns projected into the mouth. The whorl effectively formed the lower jaw's entire dentition. New teeth grew continuously and were added to the whorl, while older teeth were retained inside it. Smithsonian fossils are therefore cataloged as a “symphysial tooth whorl,” meaning a tooth whorl in the front central part of the lower jaw. Helicoprion is often described as a bizarre prehistoric shark. Phylogenetically, however, it belonged to the holocephalan lineage and was therefore more closely related to modern chimaeras than to modern sharks.
The 2013 CT reconstruction showed that Helicoprion's tooth whorl occupied the lower jaw arch and was supported along its midline.
