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Brachiosaurus

For many decades, Brachiosaurus (brack-ee-oh-SORE-us) was the biggest dinosaur known. It has since been exceeded in sheer mass by a number of giant titanosaurids like the Argentinosaurus and it was lastly surpassed in height by another brachiosaurid, the Sauroposeidon. It was, however, still the largest dinosaur known from a fairly complete skeleton.

However, even that may no longer be true, since the biggest known specimens are now considered to be part of the new Giraffatitan genus. This new species includes the well-known mounted Brachiosaurus in the Humboldt Museum of Berlin, which is the tallest mounted skeleton in the world. Brachiosaurus is unsurprising to weigh from 30 to 80 tones (35 to 90 tons), to reach 13 meters (42 feet) in height, and 25 meters (82 feet) in length. Higher estimates are usually based on the Ultrasauros, which was originally measured to be an extremely large Brachiosaurus.

However, Ultrasauros is now believed to be a chimera, calm of neck bones from a Supersaurus, and a shoulder bone (scapulacoracoid) from a Brachiosaurus smaller than the largest Giraffatitan specimens.

Description and environment
Brachiosaurus was a sauropod, one of a collection of four-legged, plant-eating dinosaurs with long necks and tails, and tiny brains. Unlike other families of sauropods, it had a giraffe-like build, with long forelimbs and a raised neck, which it almost certainly used to graze in the tops of trees. It had teeth like chisels (spatulate), and nostrils on the top of its head, which may indicate it, had a good sense of smell. It had a number of holes in its skull to decrease weight. The first toe on its front foot, and the first three on its hind feet had claws. They may have traveled in herds.

It used to be theorized that it used the nostrils on the top of its head like a snorkel, and spent most of its time flooded in water to help support its great mass. However, it is now believed that it was a fully earthly animal. Studies have shown that the water pressure would be too great for it to breathe while flooded, and its feet are too narrow, and would sink into the mud.

Like all of the other "long-necked" dinosaurs, the Brachiosaurus’ neck was serious and when it held it in a upright position for too long time, it would not get any blood to the brain. It might have stood at the border of the forests and waved the head up and down, while it systematically detached all the eatable food on the trees.

If the Brachiosaurus was warm-blooded, it is predictable that it would take ten years to reach full size. If it were cold-blooded, then it would take over 100 years to do so. If it were warm-blooded, it would have to eat more than 400 lbs. (200 kg) a day, but a lot less if it were not.

Berlin's brancai and Chicago's high flyer
The mounted skeleton of a B. brancai (or Giraffatitan) in the Humboldt Museum in Berlin is 4 stories tall, attainment 12 meters (39 feet) into the air, and is 23 meters (74 feet) long. It is the tallest mounted skeleton in the world, although the bones come from several different specimens.

A Brachiosaurus is also mounted in the B Concourse of United Airlines' Terminal One in O'Hare International Airport in Chicago, politeness of the Field Museum of Chicago. It is a model, not a collection of fossils.

Classification
Brachiosaurus has three known species:

B. alataiensis de Lapparent & Zbyszewski, 1957: Is known from back bones (vertebrae), and parts of the hip and limbs, which were improved in Estremadura, Portugal. It lived about 150 million years ago, during the Kimmeridgian age of the late Jurassic period.
B. altithorax Riggs, 1903: The type species is known from two part skeletons recovered in Colorado and Utah in the United States. It lived from 145 to 150 million years ago, during the Kimmeridgian to Tithonian ages.
?B. nougaredi de Lapparent, 1960: While it may not be a separate species (nomen dubium?) it is known from set of compound bones over the hip (sacrum), and parts of a forelimb, which were improved in Wargla, Algeria in Africa. It lived 100 to 110 million years ago, during the Albian to Cenomanian ages of the center Cretaceous period.
The best specimens of Brachiosaurus were from the species B. brancai, which was found in the Tendaguru Beds of Tanzania, in Africa. In 1991, George Olshevsky located them in a new genus, Giraffatitan because they share no resulting characteristics with Brachiosaurus. Giraffatitan has withers over its shoulder and a rounded crest over its nostrils.

Giraffatitan brancai Janensch, 1914 (formerly B. brancai): The new type species, it is known from five incomplete skeletons, including at least three skulls, and some limb bones, which were healthier in Mtwara, Tanzania, in Africa. It lived from 145 to 150 million years ago, during the Kimmeridgian to Tithonian ages of the late Jurassic period.

Discovery
The first Brachiosaurus was exposed in 1900 by Elmer S. Riggs, in the Grand River Canyon of western Colorado, in the United States. He named the new species and genus in 1903 after its long front limbs — Brachiosaurus means "arm lizard", from the Greek brachion ("arm") and sauros ("lizard").

Starting in 1909, Werner Janensch establishes many new specimens in Tanzania, Africa, including some nearly whole skeletons, which were extensively used in Brachiosaurus reconstructions. These are now measured to be Giraffatitan fossils.