Brachiosauridae

The Brachiosauridae ("arm lizards", from Greek brachion (βραχίων) = "arm" and sauros = "lizard") are a family or clade of herbivorous, quadrupedal sauropod dinosaurs. These giants had long necks that let them reach leaves on tall trees that other sauropods could not reach. Their thick, spoon-shaped teeth helped them eat tough plants more easily than other sauropods.

One of the most famous Brachiosaurids is Brachiosaurus, which was once thought to be the largest land animal ever. Brachiosaurids lived in places that are now North and South America, Africa, Europe, and Asia. They first appeared in the fossil record during the Late Jurassic period, maybe even earlier in the Middle Jurassic, and disappeared in the Late Cretaceous period. Their wide distribution across many continents suggests they lived before the supercontinent Pangaea broke apart.

Brachiosauridae is defined as all titanosauriforms more closely related to Brachiosaurus than to Saltasaurus. They are one of the three main groups in the clade Titanosauriformes, along with the Euhelopodidae and the Titanosauria.

Description

The Brachiosauridae were a group of very large, four-legged dinosaurs. They had thick, spoon-shaped teeth that helped them bite through tough plants. Their long necks, made of twelve to thirteen very long neck bones, allowed them to reach leaves high up in trees that other dinosaurs could not.

Brachiosaurids often lived in areas with tall conifer trees, which provided them with food. Their long necks could bend upward, letting them eat from treetops as high as about 14 metres (46 feet) above the ground. They had longer front legs than hind legs, giving them a unique way of moving, and could walk faster when needed.

History of findings

In 1903, Elmer Samuel Riggs described and named Brachiosaurus. He created a new sauropod family called Brachiosauridae in 1904. Since then, how scientists group these dinosaurs has changed many times. Today, Brachiosauridae is recognized as a distinct group within the larger Titanosauriformes.

Important discoveries include the "French Bothriospondylus" found in France in 1943. In 2017, it was identified as Vouivria damparisensis, representing the oldest known brachiosaurid. Many brachiosaurid species have been named since the late 1990s, helping scientists understand this group better.

Paleo biogeographic distribution

Definitive brachiosaurid remains have been found from the Late Jurassic period to the Early Cretaceous, from about 157 to 100 million years ago. They appeared in the Late Jurassic and have been discovered in many places, including North America, Africa, Europe, and South America. This suggests they originated earlier, in the Middle Jurassic, before the continents separated.

In the Early Cretaceous, brachiosaurids were mainly found in North America. However, recent discoveries in Lebanon and Colombia show that they also lived in other parts of the world at that time. These findings help scientists understand where brachiosaurids lived and how their numbers may have changed over millions of years.

Classification

Brachiosauridae is one of the two major clades of Titanosauriformes, a diverse group of sauropods that lived during the Late Jurassic and Cretaceous periods in Laurasia and Gondwana. Europasaurus is considered the most basic member of this group.

Titanosauriformes included some of the largest and smallest known sauropods. This group had three main families: Brachiosauridae, which lived in the Late Jurassic and Early Cretaceous periods, Euhelopodidae from mid-Cretaceous East Asia, and Titanosauria from the Cretaceous in Gondwana. Traditionally, Brachiosauridae included Brachiosaurus, but recent studies sometimes separate it into B. altithorax and Giraffatitan brancai.