The dinosaur with 500 teeth is called the Nigersaurus. This herbivorous dinosaur lived during the Late Cretaceous period, approximately 115 to 105 million years ago. Its teeth were small and constantly replaced, and it likely used them to chew tough plants. Despite having so many teeth, the Nigersaurus had a relatively small head, suggesting that it primarily ate a soft, low-lying vegetation. Its name comes from its discovery in Niger, Africa, and it is one of the most unusual dinosaurs known to science.