Brachiosaurus was one of the tallest long-necked dinosaurs. This ground shaking herbivore occupied North America during the Late Jurassic, about 153 million years ago.
The first partial skeleton of Brachiosaurus was discovered and excavated duringexpeditions from the Field Columbian Museum to Colorado, USA, in1900. It was described and named by American paleontologist andexpedition leader, Elmer Riggs, in 1903. Riggs gave it the fullname Brachiosaurus altithorax, and after the fossil material wasprepared, he proceeded to describe it in more detail in 1904. Brachiosaurus is one of the rarest dinosaurs in the MorrisonFormation of America and only one other partial skeleton is knownfor certain, found in Utah. This means that the head and neck of Brachiosaurus altithorax are not known with certainty, andso estimates of the total length and height of the animal are basedon its close relatives.
A second species of Brachiosaurus was named in 1914 from Tanzania, Africa. Thisspecies, named Brachiosaurus brancai at the time, was represented by muchmore material and shaped the popular image of Brachiosaurus. However, this African species differedsignificantly from the American one. The American B. altothorax had a longer and deeper body, more widelysplayed arms, and a longer tail. This led to Brachiosaurus brancai being given a new name, Giraffatitan, in 1988. This classification gained widespreadacceptance following a thorough comparison of Brachiosaurus specimens in 2009, and today there is only onevalid species of Brachiosaurus, the American B. altithorax.
Most early reconstructions wrongly portrayed sauropods asamphibious swamp-dwellers that spent their lives under water tosupport their great weight. In this scenario, it was thought, Brachiosaurus could use its long vertical neck, and nostrilson the top of its head, to breath at the surface. In reality, Brachiosaurus stood tall on straight pillar-like legs andwas fully terrestrial. It lived on land and used its long neck tobrowse on the highest vegetation out of reach of other dinosaurs.Although its bony nostril openings are situated on top if itsskull, the fleshy nostrils were positioned far forwards inlife.
Brachiosaurus lived in the Late Jurassic about 153 millionyears ago. It shared its habitat with several other famous NorthAmerican dinosaurs including the plated Stegosaurus, long-necked Diplodocus, and predatory Allosaurus. However, adult Brachiosaurus were so large they were probably immune toattacks from predators.