Ootacanthus

Ootacanthus is a genus of extinct cartilaginous fish belonging to the order Eugeneodontiformes. These ancient sharks lived during the Permian period, approximately 299 to 252 million years ago. The most distinctive feature of Ootacanthus, and indeed all eugeneodonts, is the presence of a singular, spirally arranged tooth whorl on the lower jaw. This unique structure served as a battery of continuously growing teeth.

Fossil evidence for Ootacanthus is primarily found in marine deposits, suggesting an aquatic lifestyle. Like other eugeneodonts, Ootacanthus likely inhabited shallow to moderately deep marine environments. The exact diet and feeding habits of Ootacanthus are not fully understood, but the tooth whorl suggests a specialized feeding strategy, possibly involving crushing or grinding prey. Its body shape is inferred to be shark-like, with cartilaginous skeletons that rarely preserve as complete fossils.

The genus Ootacanthus is known from limited fossil remains, predominantly teeth and jaw fragments. This scarcity makes detailed reconstructions of its anatomy challenging. The group Eugeneodontiformes, to which Ootacanthus belongs, is characterized by this unusual dentition and ultimately went extinct at the end of the Permian period. The name Ootacanthus is derived from Greek, referring to its distinctive egg-shaped teeth.