Brachiosaurus is a famous long-necked herbivorous dinosaur from the Jurassic, known for its massive size

Brachiosaurus is a large herbivorous dinosaur that lived in the Late Jurassic and belongs to the suborder Sauropoda. It gets its name because its forelimbs are noticeably longer than its hind limbs; the original meaning of the name is "arm lizard." Its fossils have mainly been unearthed in North America, and thanks to its enormous size and distinctive stance with the front high and the rear low, it has become one of the giant dinosaurs most familiar to the general public.

The most striking feature of Brachiosaurus is its highly raised neck. When standing, its shoulders are far higher than its hips, and its overall silhouette somewhat resembles a giraffe. This body structure allowed it to feed on the tender leaves and branches at the tops of tall trees, creating ecological separation from other sauropods that foraged lower down. Its head is relatively small, its nostrils are located above the top of its head, and its teeth are spoon-shaped, suitable for stripping vegetation, while tough leaves were processed through a long digestive process.

In terms of classification, Brachiosaurus belongs to the family Brachiosauridae, whose members generally have long necks and well-developed forelimbs. Similar fossils found in Africa in the past were long classified under the genus Brachiosaurus, but later many scholars argued that they should be separated into the genus Giraffatitan, so when Brachiosaurus is mentioned now, it generally refers to this genus unearthed in North America.

Brachiosaurus often appears in museum reconstructions and popular science books, and is a commonly used representative species when introducing Mesozoic ecology. It is worth noting that it was a purely terrestrial animal and did not dive into water to live as some early speculations suggested; this misunderstanding has now been widely clarified. Compared with long-necked dinosaurs such as Diplodocus and Brontosaurus, Brachiosaurus has longer forelimbs and a stance with the front high and the rear low, which is an important difference for identifying the two.