Which sauropod dinosaur had a wide muzzle and over 500 teeth?

The sauropod dinosaur with a wide muzzle and more than 500 teeth was Nigersaurus. This unusual plant-eater had a broad, almost straight-edged mouth unlike the tapered snouts of many other sauropods.

Nigersaurus lived in what is now Niger during the Middle Cretaceous, about 115–105 million years ago. Its jaws held dense dental batteries: rows of active teeth backed by multiple replacement teeth. The dinosaur could replace individual teeth rapidly, with estimates suggesting a new tooth position could be renewed about every 14 days.

Its tooth rows were rotated transversely so that the teeth were concentrated at the front of the mouth. This arrangement probably helped Nigersaurus crop soft vegetation close to the ground. Its diet may have included ferns, horsetails, and flowering plants. Its lightweight, air-filled skeleton also reflects the extensive air-sac system common among sauropods.

Nigersaurus was a rebbachisaurid sauropod, related to diplodocoid dinosaurs. Camarasaurus, Brachiosaurus, and Diplodocus were also sauropods, but they did not share Nigersaurus’s distinctive wide muzzle and extreme dental battery.