Classification: Dinosauria – Saurischia – Sauropoda - Gravisauria - Eusauropoda - Neosauropoda – Macronaria – Titanosauriformes – Brachiosauridae
Time Period: Late Jurassic
Location: United States and Europe
Diet: Herbivore
The sauropod Brachiosaurus traveled in herds in the western United States during the Late Jurassic. Its stomping grounds consisted of low-lying drainage basins that swallowed runoff from the emergent Rocky Mountains to the west. These lowlands were scarred by crisscrossing streams and rivers and were dotted with swampy lowlands, lakes, river channels, and floodplains. (Brachiosaurus remains have also been allegedly found in Portugal). This infamous sauropod walked on four pillar-like legs; its front legs were longer than its back legs, so that its body sloped downwards towards its short tail. Its name means ‘arm reptile,’ in reference to the fact that its arms (forelegs) were longer than its rear legs. Some scientists believe it could rear back on its hind legs to reach super high foliage, though some believe it kept its four legs on the ground at all times.
Brachiosaurus’ neck reached vertical rather than horizontal like diplodocids. This gave it a feeding advantage: whereas most of its sauropod contemporaries were low-browsing diplodocids, Brachiosaurus could browse foliage up to fifty feet off the ground to feed on high conifers and ginkgoes. Air sacs along the neck and trunk of Brachiosaurus lightened the strain needed to keep its neck vertical. These air sacs connected to its lungs, thus lowering the body density. Brachiosaurus couldn’t chew its food, as its jaws were only capable of opening and closing (it couldn’t move its jaws side-to-side in a grinding motion). Its 52 spatulate (spoon-like) teeth cropped conifer needles, palm-fronds, ginkgo leaves, and even towering horsetails that grew along the many waterways of the Morrison. It would’ve needed to consume up to 440 pounds of food each day, and this food was swallowed unchewed and passed into a gizzard where gastroliths (stomach stones) crushed the food to a pulp for digestion.
Fossils similar to those of North America’s Brachiosaurus were discovered in Africa’s Tendaguru Formation in 1914; scientists believed the fossils to represent a new species of Brachiosaurus, but further study indicated significant morphological differences, so the fossils became a new genera altogether: Giraffatitan. Giraffatitan’s crest bone, rising from the top of the skull, is much larger than that in Brachiosaurus (interestingly, most modern depictions of Brachiosaurus include a crest bone more in line with that of Giraffatitan than Brachiosaurus). While it was once believed Brachiosaurus’ nostrils were set atop its skull crest, modern reconstructions place them lower down on the high forehead, right above the eyes, in a kink that angled from the forehead into the low snout. This reconstruction has led some scientists to postulate that the crest was a resonating chamber that could’ve amplified Brachiosaurus’ vocalizations.
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| a scene from the Morrison Formation; Brachiosaurus in the foreground, Camarasaurus in the background, and early ornithopods along the forest floor |
