Danielle Dufault May 12, 2021 Evolution of a smile: 400 million year old spiny fish overturns shark theory of tooth origins Benedict King, Max Planck Institute for Evolutionary Anthropology; Martin Rücklin, Naturalis Biodiversity Center, and Philip C J Donoghue, University of Bristol Scientists have long believed that sharks were the first vertebrates to evolve teeth. Our new study reveals a more complex history.