Brachiosaurus

MEANING: Arm lizard

PERIOD: Late Jurassic

CONTINENT: North America

Brachiosaurus is a sauropod dinosaur named for its forelimbs, which were longer than its hindlimbs. This resulted in a steeply inclined posture, and a proportionally shorter tail. Brachiosaurus is estimated to have been about 20 m long, weighing up to 50 t. It was likely a high browser, consuming vegetation as high as 9 m off the ground.

Brachiosaurus is from the Late Jurassic. The Late Jurassic was a dynamic period, spanning from about 162 to 143 million years ago. The continents were continuing to drift apart, and the supercontinent Pangaea had fully split into Laurasia in the north and Gondwana in the south. This continental rearrangement led to the formation of large inland seas and shallow coastlines that fostered diverse ecosystems. The climate during the Late Jurassic was warm and humid, with lush forests of conifers and ferns that stretched across much of the continents, creating a rich ecosystem where dinosaurs flourished the dominant land animals.

Dinosaurs continued to diversify through the Late Jurassic, with some of the most famous species evolving in this time. Many well-known sauropods, such as Brachiosaurus and Apatosaurus roamed the land, exhibiting niche partitioning with their selectively distinct neck positions. Alongside them, stegosaurs became widespread, their plates and spikes making them one of the era's most recognizable groups. Theropods like Allosaurus and Ceratosaurus were the apex predators, evolving large, powerful bodies and sharp teeth that allowed them to hunt the gigantic herbivores. The early evolution of birds was taking place, setting the stage for the numerous species that would fill the skies in the eras to come.

Unlike the dramatic mass extinctions that marked the beginning and end of the Mesozoic, the Jurassic Period ended without a sharp boundary. As the continents continued to drift, ecosystems gradually transformed into unique habitats that supported the more specialized dinosaur species of the Cretaceous.

Brachiosaurus is a brachiosaurid. Brachiosauridae is a distinctive family of sauropod dinosaurs best known for their unusual limb proportions and towering stance. Unlike most other sauropods, brachiosaurids had longer front legs than hind legs, giving their bodies an upward tilt and allowing them to reach higher vegetation than their contemporaries. Their long necks, elevated shoulders, and deep chests contributed to a giraffe-like silhouette, and this anatomical design likely allowed them to browse tall conifer forests with minimal competition.

Brachiosaurids first appeared in the Middle Jurassic and persisted into the Early Cretaceous. Fossils have been found across North and South America, Europe, Asia, and Africa. These dinosaurs were massive, the tallest potentially exceeding 12 meters in height. While not as long as some of the later titanosaurs, brachiosaurids were among the most impressive of the Jurassic giants. Their high-browsing niche and colossal size made them a key component of their ecosystems, shaping the structure of ancient forests and the evolution of other herbivores and predators alike.