In a staghorn coral reef at Las Clavellinas on the northern edge of Enriquillo Lake in Dominican Republic, Erin Dillon, a fellow at the Smithsonian Tropical Research Institute, talks about how she plans to extract the dermal denticles (tooth-like scales) of sharks from the 7,000-year-old reefs, and how that can help us better understand what Caribbean shark communities used to be like before humans.