Quick question

What did Diplodocus eat?

Diplodocus was herbivorous, meaning they only ate plants.

Its narrow teeth were arranged like a rake, which helped them strip leaves from gingko and conifer trees. Diplodocus would have had to eat all day to be able to survive on just leaves.

Dinosaurs like Dippy had 42 teeth but over their lifetime they would have grown many more, as it's been estimated they replaced each tooth every 35 days. Without this ability, the dinosaur would have eventually lost all its teeth and with them, the ability to eat. Some animals today, such as lizards and crocodiles, also constantly replace their teeth, whereas we humans only have two sets in our lifetime.

See Dippy's skull and teeth up close

Next question: 

How did Diplodocus move?