Diplodocus ranks among the longest dinosaurs ever discovered, with a total length reaching up to 27 meters. Its remarkable body plan consisted of an 8-meter neck, a 5-meter torso, and an exceptionally long, 14-meter tail. Despite its impressive length, it was relatively slender and is estimated to have weighed around 12 tons.

This sauropod lived approximately 150 million years ago in what is now North America and England. Its name, meaning "double beam," refers to the distinctive pair of sandal-shaped bony protrusions found on its tail vertebrae.

The animal’s head was surprisingly small, no larger than a horse’s, yet it belonged to a creature as long as three buses. Diplodocus possessed teeth only at the front of its jaws; these resembled small pencils, specialized for stripping leaves from branches without chewing. It had a massive stomach capable of grinding tough vegetation, primarily the needle-like leaves of coniferous trees.

Notably, its nostrils openings were positioned high on the top of its skull, a feature that once led scientists to speculate that Diplodocus might have lived partially aquatic in lakes and rivers. It also had powerful back muscles, which likely enabled it to rear up on its hind legs to browse foliage from the tallest trees—reaching heights equivalent to a four-story building.