The Apatosaurus was a leaf eater, it also swallowed rocks or stones to help it digest its food. Because of its long neck the Apatosaurus only ate from tall and large trees.
Some say that the Apatosaurus long neck was too heavy for it to carry. This means that it might have had rest for long periods of time. So I think it did'nt get around much.
It adapted to its environment by eating leafs off the large trees and living in large packs of Apatosaurus.
Its body type was very very big some say that it was one of the biggest dinosaurs ever some stood at about 70-90 ft tall and over. It had some teeth but only ate leafs.