The Triassic period, more than 200 million years ago, is the dawn of the modern age on Earth, when most of the plant and animal groups we see today got their start. Dinosaurs began their evolution then, though they did not hit their peak until later, during the Jurassic and Cretaceous periods. Dinosaurs from the late Triassic, the period Heckert is studying, are rare. But with few bones to go by, Heckert turned to teeth. Because they are harder than bones, fossil teeth are more common than bones.
Teeth are especially important because they can tell scientists a lot about what an animal ate.
Heckert used mesh screens to sift through tons of soil from west Texas, New Mexico and Arizona in search of the teeth. Comparisons with the teeth of known dinosaur fossils gave Heckert a rough idea of what his dinosaurs might look like, but it was subtle differences in the teeth themselves that told their evolutionary story. The fossils show some early characteristics of the blunted, plant-eating dinosaur's teeth. But there are still vestiges of the sharp, flesh-tearing animal in the shape of the tooth, Heckert said.