Daily Dose of Prehistory Revival 6: Hybodus

Hybodus, meaning "Humped Tooth", was an extinct genus of very successful Chondrichthyan sharks that first appeared in the Late Permian and disappeared in the Late Cretaceous. Measuring about 6 and a half feet long, it wasn't a very large shark so it had a pair of large, bony spines that stuck out just before their two dorsal fins to discourage predation. They had two sets of teeth, extra sharp ones for catching slippery prey like fish and squid and flat ones for shelled prey. It is surprising that the Hybonts went extinct at the end of the Cretaceous, seeing as how they survived the Great Dying at the end of the Permian (which killed 90% of ocean life and 70% of land life). All in all, the Hybodonts were an extremely successful genus, lasting over 194 million years.