Brontosaurus

Chapter • Meet the dinosaur

Overview

Brontosaurus excelsus was one of the most heavily built of all diplodocids. Its barrel-shaped body was carried on four pillar-like limbs, with the forelimbs slightly shorter than the hindlimbs so that the back sloped gently forward. The neck was strikingly thick and robust compared with the slender neck of its relative Diplodocus, and was normally held out more or less horizontally. Behind the body stretched an immensely long, tapering tail held clear of the ground – no known sauropod trackway shows a drag mark. The head was tiny relative to the body, with a long snout and peg-like teeth clustered at the front of the jaws. Brontosaurus moved at a steady walk, perhaps 15–20 km/h at most, and could not truly run. Its huge neck and back vertebrae were hollowed out by air-filled chambers connected to the lungs' air sac system, exactly as in modern birds. This made the skeleton far lighter than it looks and helped move air through such a vast body. Several researchers have suggested that the unusually stout apatosaurine neck, with its massive rib-like projections underneath, may have been used in displays or even in neck-to-neck contests between males. As a herbivore, Brontosaurus browsed on ferns, horsetails, cycads and conifer foliage. The peg-like teeth were useless for chewing – they worked as a rake that stripped leaves and shoots, which were then swallowed whole and fermented slowly in a capacious gut. Tooth wear shows that teeth were replaced at a remarkable rate, roughly one new tooth per position every month. The long neck let the animal sweep a wide feeding area while keeping its heavy body still, saving a great deal of energy. Othniel Charles Marsh described Brontosaurus excelsus in 1879 from a skeleton found at Como Bluff, Wyoming, in the middle of the bitter "Bone Wars" with his rival Edward Drinker Cope. As early as 1903 Elmer Riggs argued that Brontosaurus was simply a mature Apatosaurus, and the name vanished from science – though never from popular culture. In 2015 Emanuel Tschopp, Octávio Mateus and Roger Benson published a sweeping statistical analysis of diplodocid skeletons and concluded that the differences were large enough to restore Brontosaurus as a genus in its own right. The question is still debated, but the thunder lizard has its name back.

Chapter • Where it lived

Habitat

Brontosaurus lived in the Late Jurassic, roughly 156–146 million years ago, on the broad plains of western North America. All confirmed finds come from the Morrison Formation, which crops out across Wyoming, Colorado, Utah and Oklahoma. The landscape was a semi-arid floodplain with strongly seasonal wet and dry periods, cut by river channels and dotted with seasonal lakes, with gallery forests of araucarias, ginkgoes and tree ferns lining the water. The holotype came from Como Bluff in Wyoming, and other important specimens are known from sites such as Nine Mile Quarry and Reed's Quarry in the same region. It shared this world with Diplodocus, Camarasaurus, Stegosaurus and the predator Allosaurus.

Chapter • Family life

Breeding

Chapter • Wild behavior

Behavior & Ecology

Did you know?

Chapter • Scientific place

Taxonomy