Brachiosaurus altithorax was described by Elmer
Riggs in 1903 based on a specimen from the
Late Jurassic (156 to 145 million years ago) of Colorado.
However, the best skeletons are from the
Tendaguru Hills of Tanzania, which, at the time
the skeletons were collected, was known as German
East Africa. Field work started in 1909 and
continued until 1912. The dig was not a small affair.
Almost $600,000 was raised to fund the dig. In
1909, 170 workers were employed, and their numbers
swelled to 500 in 1911 and 1912. About 235
metric tons of fossil material was removed. No
permits for further fieldwork have been issued for
this area since the 1920's.
Brachiosaurus was a quadrupedal, herbivorous dinosaur whose forelimbs were longer than its hind limbs. This sauropod had a very long neck which it held erect and a short tail which was held out horizontally. Spoon-shaped teeth filled most of the jaws. The nostrils were positioned on a large, dome-shaped crown over the eyes. The enlarged nasal cavity may have been used to produce sounds. If not, the animal must have had a keen sense of smell. Brachiosaurus was between 22.5 and 25 meters (85 feet) long, 16 meters (52 feet) high, and weighed between fifty and eighty tons. The animals had a maximum speed of between twenty to thirty kilometers per hour. Unlike Apatosaurus, Brachiosaurus is a relatively rare sauropod in the western United States, hinting that it may have lived a solitary existence there rather than being part of a herd. With its long, erect neck and long forelimbs, Brachiosaurus could feed on the cones and leaves of the tallest trees (conifers, cycads, and gingkoes). By feeding in the treetops, Brachiosaurus did not compete with other sauropods, such as Apatosaurus, or stegosaurs, such as Kentrosaurus, which fed at lower levels. To supply the brain with blood, Brachiosaurus's heart would have to pump at a systolic pressure of more than 630, have had four chambers, and weighed about 400 kilograms (about 882 pounds). In comparison, humans' normal systolic pressure is somewhere between 120 and 130, with a heart that weighs about 300 grams (10.5 ounces). To help move the blood along, the artery wallsmayhave been heavily muscularized, and a reservoir of oxygenated blood may have existed in the head for emergencies, when the animal was forced to change the level of its head rapidly.
Order: Saurischia (lizard-hipped dinosaurs)
Suborder: Sauropoda (long-necked herbivores)
Family: Brachiosauridae (quadrupedal herbivores whose forelimbs were longer than their hind limbs)
Genus and species: Brachiosaurua altithorax, B. atalaiensis, B. brancai, and B. nougaredi
Note: A number of competing classification schemes exist and will probably continue to do so in the future.
Geographical location: Late Jurassic of Algeria (B. nougaredi), Colorado and Utah (B. altithorax), Portugal (B. atalaiensis), and Tanzania (B. brancai)
Habitat: In the United States, Brachiosaurus is a relatively rare sauropod in the dry habitats represented by the Morrison Formation; in Tanzania, Brachiosaurus was far more numerous in the mesic (moist) habitats characteristic of the Tendaguru Formation
Gestational period: Although no eggs have been found, Brachiosaurus was undoubtedly an egg layer; the frequency at which eggs were laid, the time it took for the eggs to hatch, and the reproductive life span of the adults are unknown
Life span: Based on mammalian models, sexual maturity would be reached after ten years and the life span was probably in excess of one hundred years
Special anatomy: The neural spines on the cervical vertebrae of the brachiosaurids were not V-shaped as they were in the diplodocids; instead, the neural spines on the vertebrae at the junction of the neck and back were highly elongate for attachment of the muscles that held the neck and head erect, resulting in a pronounced hump over the shoulders; the centrum of each vertebra contained several pleurocoels
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