The dinosaur with 500 teeth is Nigersaurus. Nigersaurus is a genus of rebbachisaurid sauropod dinosaur that lived during the middle Cretaceous period, about 115 to 105 million years ago. Its broad, straight-edged muzzle was tipped with more than 500 replaceable teeth, which were arranged in dental batteries. The upper jaws contained 60 rows of small, needle-shaped teeth, while the lower jaws had no less than 68 very sharp teeth. These teeth were also replaceable, meaning Nigersaurus constantly required fresh teeth as older ones were worn down or lost. The enamel on the teeth of Nigersaurus was highly asymmetrical, ten times thicker on the outwards facing side than on the inner side. Nigersaurus had a delicate skull and an extremely wide mouth lined with teeth especially adapted for browsing plants close to the ground.