DESPITE the fearsome reputation of modern sharks, their ancient relatives never quite matched the predatory skills of their reptile or mammal rivals. A new analysis of their teeth helps explain why.
Until about 65 million years ago, the great ocean-going predators were reptiles that went extinct at the same time as their dinosaur cousins. Amazingly, their ecological niche remained empty for 15 million years, until marine mammals came along. For a long while, it seems, sharks were unable to stay in the hunt.
Chuck Ciampaglio of Wright State University in Celina, Ohio, looked at the shape of the teeth of…
