Brachiosaurus

Brachiosaurus () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic. About 155.6 to 145.5 million years ago. It was first described by American paleontologist Elmer S.

Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur Brachiosaurus altithorax; the generic name is Greek for "arm lizard". In reference to its proportionately long arms, and the particular name means "deep chest".

Brachiosaurus is estimated to have been between 18 and 22 meters (59 and 72 ft) long; body mass estimates of the subadult holotype specimen range from 28.3 to 46.9 metric tons (31.2 to 51.7 short tons). It had a disproportionately long neck, small skull, and large overall size. All of which are typical for sauropods.

Atypically, Brachiosaurus had longer forelimbs than hindlimbs. Which resulted in a steeply inclined trunk, and a proportionally shorter tail. Brachiosaurus is the namesake genus of the family Brachiosauridae.

Which includes a handful of other similar sauropods. Most popular depictions of Brachiosaurus are in fact based on Giraffatitan. A genus of brachiosaurid dinosaur from the Tendaguru Formation.