What is "hybodus"

Hybodus \Hyb"o*dus\, n. [NL. See Hybodont.] (Paleon.) An extinct genus of sharks having conical, compressed teeth.

Hybodus ("humped tooth") is an extinct genus of widespread and long-lived sharks, first appearing towards the end of the Permian period, and disappearing during the Late Cretaceous. During the Triassic, Jurassic, and Cretaceous periods the hybodonts were especially successful and could be found in shallow seas across the world. For reasons that are not fully understood, the hybodonts became extinct near the end of the Late Cretaceous period.