Apatosaurus, also known as Brontosaurus, was a huge dinosaur that roamed the Earth about 150 million years ago during the Late Jurassic period. It belonged to a group of dinosaurs called sauropods, which were the largest animals to have ever lived on land. Apatosaurus had a long neck, long tail, and a massive body.

Despite its large size, Apatosaurus was an herbivore, meaning it only ate plants. It grazed on vegetation like trees, ferns, and cycads. Its teeth were adapted for cropping leaves and branches. To aid in digestion, Apatosaurus swallowed rocks called gastroliths, which helped grind up the tough plant material in its stomach.

Apatosaurus had a unique adaptation called pneumaticity, which means that some of the bones in its body were filled with air sacs. These air sacs made its bones lighter and allowed it to move more easily despite its massive size.