Dinosaurs once roamed in the vicinity of Washington D.C. They did not leave very much behind. No one has found a beautifully articulated skeleton under the city streets—the city’s most famous dinosaur, “Capitalsaurus,” is known from only fragments—but paleontologists can use isolated teeth to take a census of which kinds of dinosaurs were present in the area. In the video posted above, the Smithsonian National Museum of Natural History’s dinosaur curator Matthew Carrano explains how paleontologists identify dinosaurs on the basis of teeth alone.