Brachiosaurus

Overview

Brachiosaurus altithorax was an enormous sauropod dinosaur that roamed the Late Jurassic floodplains and forests of North America. Renowned for its elongated forelimbs and long neck, this herbivore stood around 40 ft tall at the shoulder and could reach lengths of up to 85 ft. Weighing roughly 50 tons, Brachiosaurus used its towering height to browse on treetop foliage that many other herbivores could not access.

The name “Brachiosaurus” means “arm lizard,” referring to its forelimbs being significantly longer than its hindlimbs—a feature that gave it a gently sloping back and allowed it to reach even higher vegetation. Studies on bone structure and physiology suggest it may have had a relatively high metabolism for its size, possibly aided by air sacs similar to modern birds.

Quick Facts

Diet

Ferns, cycads, conifers (Herbivore)

Speed

~10–15 mph (est.)

Weight

~50 tons

Length

~85 ft (~26 m)

Bite Force

~500 psi (estimated)

Discovery & Significance

Elmer S. Riggs first described Brachiosaurus in 1903 based on fossils discovered in the Grand River Valley (now part of Colorado, USA). Its towering stance and distinct limb proportions set it apart from other sauropods, capturing public fascination for over a century. Brachiosaurus remains a hallmark of the Morrison Formation’s spectacular dinosaur fauna, which also includes Allosaurus, Stegosaurus, and Diplodocus.

In popular culture, Brachiosaurus often appears as the quintessential “long-neck” dinosaur, famously portrayed in documentaries and films. Its fossils and life reconstructions helped shape our understanding of sauropod biology, including how such immense creatures supported their mass and accessed food sources high above the ground.

Brachiosaurus vs. Other Giant Sauropods

More Details

They say Brachiosaurus, meaning “arm lizard,” is a Late Jurassic sauropod recognized by its unusually long forelimbs and towering stance. Initially discovered in the Colorado River valley in 1900 by Elmer S. Riggs, Brachiosaurus altithorax quickly gained fame as one of the largest dinosaurs known from North America’s Morrison Formation. Measuring around 18 to 26 meters (59 to 85 ft) in length and estimated to weigh up to 49.9 metric tons, it stood out for its steeply sloping back and elongated neck. While most sauropods have hind limbs longer than their forelimbs, Brachiosaurus flipped this pattern, supporting its body with forelimbs that rose higher than its hips. This stance likely allowed it to reach vegetation at heights of 9 meters (30 ft) or more, placing it among the dominant high browsers of its time. Fossil evidence suggests a slower pace than smaller dinosaurs, but its massive size may have safeguarded it against predators such as Allosaurus and Ceratosaurus that roamed the same habitat. Originally, certain fossils from Africa and other parts of the world were attributed to Brachiosaurus, but in recent years, paleontologists have revised many of these assignments, giving rise to new genera, including Giraffatitan and Lusotitan. Consequently, the type specimen from Colorado remains the most reliably assigned material. Its known skeleton lacks a complete skull, but a tentative match from the Felch Quarry hints at a long, high-snouted head, similar to that of Giraffatitan. Brachiosaurus continues to fascinate both scientists and the public. Its towering silhouette shows up in many documentaries and films, particularly Jurassic Park, where it was the first dinosaur to appear on screen. Overall, Brachiosaurus remains an icon of just how gigantic and specialized sauropods could become during the late Jurassic, capturing our imagination with its extraordinary size and unforgettable posture. Despite debate on posture, it endures.

References & Further Reading