Brachiosaurus

***Brachiosaurus*** (/ˌbrækiəˈsɔːrəs/) is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154–153 million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur ***Brachiosaurus altithorax***; the generic name is Greek for "arm lizard", in reference to its proportionately long arms, and the specific name means "deep chest". *Brachiosaurus* is estimated to have been between 42 meters (139 ft) long; weight estimates range from 28.3 to 158 metric tons (31.2 and 164 short tons). It had a disproportionately long neck, small skull, and large overall size, all of which are typical for sauropods. Atypically, *Brachiosaurus* had longer forelimbs than hindlimbs, which resulted in a steeply inclined trunk, and a proportionally shorter tail.

*Brachiosaurus* is the namesake genus of the family Brachiosauridae, which includes a handful of other similar sauropods. Most popular depictions of *Brachiosaurus* are in fact based on *Giraffatitan*, a genus of brachiosaurid dinosaur from the Tendaguru Formation of Tanzania. *Giraffatitan* was originally described by German paleontologist Werner Janensch in 1914 as a species of *Brachiosaurus*, *B. brancai*, but moved to its own genus in 2009. Three other species of *Brachiosaurus* have been named based on fossils found in Africa and Europe; two are no longer considered valid, and a third has become a separate genus, *Lusotitan*.

The type specimen of *B. altithorax* is still the most complete specimen, and only a few other specimens are thought to belong to the genus, making it one of the rarer sauropods of the Morrison Formation. It is regarded as a high browser, possibly cropping or nipping vegetation as high as 9 meters (30 ft) off the ground. Unlike other sauropods, it was unsuited for rearing on its hindlimbs. It has been used as an example of a dinosaur that was most likely ectothermic because of its large size and the corresponding need for sufficient forage, but more recent research suggests it was warm-blooded. Among the most iconic and initially thought to be one of the largest dinosaurs, *Brachiosaurus* has appeared in popular culture, notably in the 1993 film *Jurassic Park*.

### Size

Most estimates of *Brachiosaurus altithorax*'s size are based on the related brachiosaurid *Giraffatitan* (formerly known as *B. brancai*), which is known from much more complete material than *Brachiosaurus*. The two species are the largest brachiosaurids of which relatively extensive remains have been discovered. There is another element of uncertainty for the North American *Brachiosaurus* because the type (and most complete) specimen appears to represent a subadult, as indicated by the unfused suture between the coracoid, a bone of the shoulder girdle that forms part of the shoulder joint, and the scapula (shoulder blade).[4] Over the years, the mass of *B. altithorax* has been estimated at 35.0 metric tons (38.6 short tons),[44] 28.3 metric tons (31.2 short tons),[52] 43.9 metric tons (48.4 short tons),[26] 28.7 metric tons (31.6 short tons),[4] 56.3 metric tons (62.1 short tons),[53] and 156 metric tons (164 short tons).[54] The length of *Brachiosaurus* has been estimated at 30 meters (100 ft)[44] and 42 meters (138 ft),[55][52] and its height at 17 meters (57 ft)[55] and 21 meters (69 ft).[44][56]

While the limb bones of the most complete *Giraffatitan* skeleton (MB.R.2181) were very similar in size to those of the *Brachiosaurus* type specimen, the former was somewhat lighter than the *Brachiosaurus* specimen given its proportional differences. In studies including estimates for both genera, *Giraffatitan* was estimated at 31.5 metric tons (34.7 short tons),[44] 23.3 metric tons (25.7 short tons),[4] and 34.0 metric tons (37.5 short tons).[53][42] As with the main *Brachiosaurus* specimen, *Giraffatitan* specimen MB.R.2181 likely does not reflect the maximum size of the genus, as a fibula (specimen HM XV2) is 13% longer than that of MB.R.2181.[4]

### General build

Life restoration showing hypothetical nasal ornamentation

Like all sauropod dinosaurs, *Brachiosaurus* was a quadruped with a small skull, a long neck, a large trunk with a high-ellipsoid cross section, a long, muscular tail and slender, columnar limbs.[48] Large air sacs connected to the lung system were present in the neck and trunk, invading the vertebrae and ribs by bone resorption, greatly reducing the overall density of the body.[57][58] The neck is not preserved in the holotype specimen, but was very long even by sauropod standards in the closely related *Giraffatitan*, consisting of thirteen elongated cervical (neck) vertebrae.[59] The neck was held in a slight S-curve, with the lower and upper sections bent and a straight middle section.[60] *Brachiosaurus* likely shared with *Giraffatitan* the very elongated neck ribs, which ran down the underside of the neck, overlapping several preceding vertebrae. These bony rods were attached to neck muscles at their ends, allowing these muscles to operate distal portions of the neck while themselves being located closer to the trunk, lightening the distal neck portions.[60][61]

*Brachiosaurus* and *Giraffatitan* probably had a small shoulder hump between the third and fifth dorsal (back) vertebra, where the sideward- and upward-directed vertebral processes were longer, providing additional surface for neck muscle attachment.[62] The ribcage was deep compared to other sauropods.[1] Though the humerus (upper arm bone) and femur (thigh bone) were roughly equal in length, the entire forelimb would have been longer than the hindlimb, as can be inferred from the elongated forearm and metacarpus of other brachiosaurids.[4] This resulted in an inclined trunk with the shoulder much higher than the hips, and the neck exiting the trunk at a steep angle. The overall build of *Brachiosaurus* resembles a giraffe more than any other living animal.[44] In contrast, most other sauropods had a shorter forelimb than hindlimb; the forelimb is especially short in contemporaneous diplodocoids.[63]

*Brachiosaurus* differed in its body proportions from the closely related *Giraffatitan*. The trunk was about 25–30% longer, resulting in a dorsal vertebral column longer than the humerus. Only a single complete caudal (tail) vertebra has been discovered, but its great height suggests that the tail was larger than in *Giraffatitan*. This vertebra had a much greater area for ligament attachment due to a broadened neural spine, indicating that the tail was also longer than in *Giraffatitan*, possibly by 20–25%.[4] In 1988, paleontologist Gregory S. Paul suggested that the neck of *Brachiosaurus* was shorter than that of *Giraffatitan*, but in 2009, paleontologist Mike P. Taylor pointed out that two cervical vertebrae likely belonging to *Brachiosaurus* had identical proportions.[4][44] Unlike *Giraffatitan* and other sauropods, which had vertically oriented forelimbs, the arms of *Brachiosaurus* appear to have been slightly sprawled at the shoulder joints, as indicated by the sideward orientation of the joint surfaces of the coracoids.[4] The humerus was less slender than that of *Giraffatitan*, while the femur had similar proportions. This might indicate that the forelimbs of *Brachiosaurus* supported a greater fraction of the body weight than is the case for *Giraffatitan*.

baylene

shorty

their are several species of brachiosaurus in equestria, one of the more popular species is the one made for jurassic park by ingen, the males are green with darker green stripes with red crests while the females are a peach color

one of the other species is a dark indigo with a purple underbelly and a violate back with completely black eyes with orange irises

the other species is more purple with yellow patterns and yellow spines from neck to its hyps