Otodus is an extinct genus of mackerel shark which lived during the Paleocene and Eocene epochs, approximately 60 to 45 million years ago. The name Otodus comes from Greek ὠτ (oûs “ear”) and ὀδούς, “odous (tooth)”, or “ear-shaped tooth”.
This shark is known from the fossil teeth and fossilized vertebral centra. Like other elasmobranchs, the skeleton of Otodus was composed of cartilage and not bone, resulting in relatively few preserved skeletal structures appearing within the fossil record. The teeth of this shark are large with triangular crown, smooth cutting edges, and visible cusps on the roots. Some Otodus teeth also show signs of evolving serrations. Otodus likely preyed upon marine mammals, large bony fish, and other sharks. It was among the top predators of its time.
Scientists determined that Otodus evolved into the genus Carcharocles, given substantial fossil evidence in the form of transitional teeth. Some teeth have been excavated from the sediments of the Potomac River in Maryland, USA, Ypres clay in Belgium, and western Kazakhstan, which are morphologically very similar to Otodus teeth but with lightly serrated cusplets and a serrated cutting edge. These transitional fossils suggest a worldwide evolutionary event, and support the theory that Otodus eventually evolved into Carcharocles aksuaticus and thus initiated the Carcharocles lineage.