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Brachiosaurus

Brachiosaurus

The Brachiosaurus is one of the most popular dinosaurs to appear in movies. It is one of the seven dinosaurs present in the original episode of the Jurassic Park saga (the others being Dilophosaurus, Triceratops, Gallimimus, Parasaurolophu and of course the now famous Velociraptor and Tyrannosaurus). People all remember the scene where Dr. Ellie Satler and Dr. Alan Grant almost marvel to unconsciousness in front of a flock of Brachiosaurus that majestically browses the treetops on the horizon. Dr. Grant then exclaims with great astonishment: "They move in herds. They do move in herds.".

Jurassic Park cult scene

Cult scene associated with an epic background music; all the ingredients for a big hit. But even before the Spielberg blockbuster, the Brachiosaurus was already the chosen sauropod for directors wishing to recreate the landscapes of the Mesozoic era and made appearances in other productions. Those like me who are die hard fans of the original Star Wars trilogy will be happy to hear that the creatures that serve as Jawas mount in the improved version of "A New Hope" are actually modeled on the Brachiosaurus.

Giraffe posture

It is very easy to distinguish the Brachiosaurus from other large sauropods since the front legs of this one are much longer than the hind legs. This particular trait gives it a posture that is typical of a giraffe and is also the origin of its name, "arm lizard". The humerus (bones of arms) of this dinosaur alone is more than six feet long, which is taller than most people. His neck is also very slender and flexible while his tail is rather short. This morphology allowed the Brachiosaurus to reach the high branches of trees without putting too much strain on his body. If this dinosaur still existed today, it would be able to peek through the fourth story windows of a building; the Brachiosaurus was a real giant.

Nostrils in the forehead

Brachiosaurus skull

When this new dinosaur species was discovered more than a century ago, naturalists of the time first speculated that an animal with such a colossal size (50 tons) would not have been able to bear its weight without immerging itself deep into lakes and rivers. According to this theory, it had to regularly peek its head out of the water, much like a submarine periscope, in order to eat and breathe. Having nostrils higher up on the skull is a common characteristic that is found among many other sauropods. This hypothesis, however, has been discredited after formal mechanical analysis demonstrated that at depths of more than 40 feet, the pressure of the water would have quickly suffocated the big animal. This is one of the great mysteries associated with sauropod dinosaurs such as Brachiosaurus and Diplodocus. Why would their nostrils be located in their forehead? Some attention seekers even go so far as to claim that the Loch Ness monster in Nova Scotia is nothing more than a 150 million-years-old Brachiosaurus who survived the Cretaceous holocost and now lives in the deep waters of the Scottish lagoon. This is obviously a quibble, since until now the Spinosaurus is the only dinosaur known to be a swimmer.

Terrestrial and nomadic way of life

Brachiosaurus was an animal better suited for land life rather than aquatic. It shared the North American floodplains of Upper Jurassic with many other kinds of sauropods: Apatosaurus, Camarasaurus, Diplodocus... These ecosystems were so lush and fertile that they could accommodate a whole fauna of herbivores. Most likely, these dinosaurs coexisted peacefully through different dietary adaptation strategies. While Apatosaurus and Diplodocus fed on shrubs and low bushes, Brachiosaurus concentrated on tall branches. Studies have shown that adult sauropods consumed an average of 400 kg (880 pounds) of dry plants every day. The jaw of Brachiosaurus was thick and its spoon-shaped teeth were made to pull out the vegetation rather than to chew it. These animals were almost certainly nomadic, slowly migrating in herds to new regions after exhausting the plant resources of a place. The diet of this dinosaur consisted mainly of conifers, cycads and ginkgos.

Giraffatitan, the African double of Brachiosaurus

Giraffatitan
Giraffatitan flock

Brachiosaurus was not the only brachiosaurid of the time. Other lesser-known dinosaurs exhibited the same bodily forms usually associated with the brachiosaur family: a long neck, a short tail, and longer forelegs than hind legs. There is Astrodon, Bothriospondylus, Sauroposeidon and the unmissable Giraffatitan. Giraffatitan lived at the same time as Brachiosaurus but in North Africa rather than America. Aside from the fact that his neck was even longer, this creature was a perfect double of Brachiosaurus. Giraffatitan was so similar to Brachiosaurus in all points of view that paleontologists are unable to decide whether it is two different species of dinosaurs or the same species that has evolved in regions characterized by different conditions. This is exactly the same situation as with Diplodocus and Seismosaurus.

Life expectancy beyond the century

These dinosaurs were so massive that when they managed to reach adult size their life expectancy could easily exceed the century. It was virtually impossible, even for a large carnivorous predator like Allosaurus, to attack healthy adult sauropods. The size of these animals was simply incomparable; they would usually die of old age or degenerative diseases. Small and juveniles were protected by herds until they were no longer threatened by the tyrannosaurs of the time. The Brachiosaurus build combined with his cold-blooded reptilian metabolism made it a long-term creature. Paleontologists believe that sauropods took a long time to warm up under the sun and just as long a moment to dissipate the accumulated heat during the night resulting in a stable body temperature.

Headless fossils

Brachiosaurus fossil

A very strange fact of the Brachiosaurus is that his skull was weakly attached to the rest of his body and thus easily detached by predators or natural erosion after death. In 1883, Othniel Marsh first found the solitary skull of a great sauropod near Garden Park that he initially attached to a reconstruction of Apatosaurus, not knowing what to do with it. Ironically, a few years later, the first Brachiosaurus fossil was unearthed in Colorado by Elmer Riggs and a team of researchers sponsored by the Chicago Museum of Natural History and was largely complete with the exception of the skull. The specimen was named Brachiosaurus altithorax. In 1914, nearly a dozen years later, a German paleontologist found a scattered giant sauropod fossil in the Tanzania region of the eastern african coast. He mistakenly identified it as another species of brachiosaurus and named the vestiges Brachiosaurus brancai. However, it is now known from the theory of continental drift that they are two distinct species although they are extremely similar from an anatomical point of view. Giraffatitan, or "giant giraffe", is much better known than Brachiosaurus largely because more complete fossils are available. Although several vestiges have been found in some other states of the American Midwest, Brachiosaurus fossils are rare. In fact, a lot of information is extrapolated from what we know about the African Brachiosaurus, the Giraffatitan.

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