Brachiosaurus altithorax BRAK-ee-oh-SOR-us
"Arm lizard"
You 1.8 m (5.9 ft) tall
Brachiosaurus 22 m (72 ft) long
13 people holding hands
- Length
- 22 m (72 ft) — About 22 m long, 12 m tall, ~30 tonnes — front legs longer than the back.
- Period
- Late Jurassic (156–145 Mya)
- Place
- North America · Western United States
- Food
- Herbivore — High-growing leaves and branches — neck held up like a giraffe to reach tree tops.
Brachiosaurus was built like a giraffe scaled up to bus-sized. Its front legs were longer than its back legs, so its body sloped upward and its neck rose almost vertically, letting it reach treetops other sauropods couldn’t touch. The huge nostrils on top of the skull confused early scientists, who thought it might have lived in water — modern reconstructions put them firmly on land.
What we know
- Front legs longer than back legs, giving the body an upward slope.
- Reached about 12 m tall at the head — taller than a 3-story building.
- Lived alongside Allosaurus, Stegosaurus, Diplodocus, and Apatosaurus.
- Lighter, hollow-boned skeleton compared to other giant sauropods of its time.
What we guess
- Exact neck posture — early models held it nearly vertical; newer work suggests less extreme.
- How much it ate per day — estimates range from 200 to 400 kg of plants.
- How it pumped blood up to the head — required either a huge heart or a clever blood-pressure system.