← Rex's Notes
Brachiosaurus
Built like a four-story crane.
Said: BRACK-ee-uh-SOR-us
Era: Jurassic · 154 to 150 million years ago
Diet: Herbivore
Habitat: Open conifer forests of western North America
Size: as long as a tennis court and as tall as a four-story building.
What it was like
Brachiosaurus had front legs longer than its back legs, like a giraffe. It probably ate around 200 kilograms of leaves every single day. That is roughly 1,000 heads of lettuce.
What we know now
Unlike most sauropods, Brachiosaurus held its neck more vertically, though biomechanical studies suggest blood pressure to the brain remained a problem requiring complex circulatory adaptations. Bone histology across close sauropod relatives points to fast growth — adult body mass reached in roughly 20 to 30 years, not the half-century older estimates assumed. Recent isotope work places it browsing primarily at heights above 9 meters, niche-partitioning from Diplodocus.
Notes
- Nostrils sat on top of the skull, in front of the eyes.
- Its heart may have weighed over 200 kg.
- The genus is named for the unusually long forelimbs, not the neck.