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Brachiosaurus

Brachiosaurus

Overview
Brachiosaurus ˌbrækiəˈsɔrəs is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of sauropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

 from the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...

 of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. It was first described by Elmer S. Riggs
Elmer S. Riggs
Elmer Samuel Riggs was an American paleontologist known for his work with the Field Museum of Natural History in Chicago, Illinois. He was born in Trafalgar, Indiana, and moved with his family to Kansas at a young age...

 in 1903 from fossils found in the Grand River Canyon (now Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

) of western Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

, in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Riggs named the dinosaur Brachiosaurus altithorax, declaring it "the largest known dinosaur". Brachiosaurus had a proportionally long neck, small skull, and large overall size, all of which are typical for sauropods.
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Encyclopedia
Brachiosaurus ˌbrækiəˈsɔrəs is a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of sauropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

 from the Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...

 of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. It was first described by Elmer S. Riggs
Elmer S. Riggs
Elmer Samuel Riggs was an American paleontologist known for his work with the Field Museum of Natural History in Chicago, Illinois. He was born in Trafalgar, Indiana, and moved with his family to Kansas at a young age...

 in 1903 from fossils found in the Grand River Canyon (now Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

) of western Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

, in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Riggs named the dinosaur Brachiosaurus altithorax, declaring it "the largest known dinosaur". Brachiosaurus had a proportionally long neck, small skull, and large overall size, all of which are typical for sauropods. However, the proportions of Brachiosaurus are unlike most sauropods. The forelimbs were longer than the hindlimbs, which result in a steeply inclined trunk, making the overall body shape reminiscent of a modern giraffe
Giraffe
The giraffe is an African even-toed ungulate mammal, the tallest of all extant land-living animal species, and the largest ruminant...

. Also, while the tail is a typical long dinosaur tail, it was relatively short for a sauropod.

Brachiosaurus is the namesake genus of the family Brachiosauridae
Brachiosauridae
Brachiosauridae are a family of dinosaurs, whose members are known as brachiosaurids. They were herbivorous quadrupeds with longer forelegs than hind legs - the name derives from the Greek for arm lizard - and long necks...

, which includes a handful of other similar sauropods. Much of what is known by laypeople about Brachiosaurus is in fact based on Giraffatitan brancai
Giraffatitan
Giraffatitan, meaning "giraffe titan", is a genus of sauropod dinosaur that lived during the late Jurassic Period . It was originally named as an African species of Brachiosaurus...

, a species of brachiosaurid dinosaur from the Tendaguru
Tendaguru
The Tendaguru Beds are a fossil-rich formation in Tanzania. It has been considered the richest of Late Jurassic strata in Africa. Continental reconstructions show Tendaguru to have been in the southern hemisphere during the Late Jurassic. Tendaguru is similar to the Morrison Formation except in...

 Formation of Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

 that was originally described by German paleontologist Werner Janensch
Werner Janensch
Werner Ernst Martin Janensch was a German paleontologist and geologist.Janensch's most famous contributions stemmed from the expedition he led with Edwin Hennig to the Tendaguru Beds in what is now Tanzania...

 as a species of Brachiosaurus. Recent research shows that the differences between the type species of Brachiosaurus and the Tendaguru material are significant enough that the African material should be placed in a separate genus. Several other potential species of Brachiosaurus have been described from Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

 and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, but none of them are thought to belong to Brachiosaurus at this time.

Brachiosaurus is one of the rarer sauropods of the Morrison Formation. The type specimen
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 of B. altithorax is still the most complete specimen, and only a relative handful of other specimens are thought to belong to the genus. It is regarded as a high browser
Browsing (predation)
Browsing is a type of herbivory in which an herbivore feeds on leaves, soft shoots, or fruits of high growing, generally woody, plants such as shrubs. This is contrasted with grazing, usually associated with animals feeding on grass or other low vegetation...

, probably cropping or nipping vegetation as high as possibly 9 metres (29.5 ft) off of the ground. Unlike other sauropods, and its depiction in Jurassic Park
Jurassic Park (film)
Jurassic Park is a 1993 American science fiction adventure film directed by Steven Spielberg. The film is based on the novel of the same name by Michael Crichton. It stars Sam Neill, Laura Dern, Jeff Goldblum, Richard Attenborough, Martin Ferrero, and Bob Peck...

, it was unsuited for rearing on its hindlimbs. It has been used an example of a dinosaur that was most likely ectothermic due to its large size and the corresponding need for forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...

, but more recent research finds it to have been warm-blooded
Warm-blooded
The term warm-blooded is a colloquial term to describe animal species which have a relatively higher blood temperature, and maintain thermal homeostasis primarily through internal metabolic processes...

.

Description



Like all sauropod dinosaurs, Brachiosaurus was a quadrupedal animal with a small skull, a long neck, a large trunk with a high-ellipsoid cross section, a long, muscular tail and slender, columnar limbs. The skull had a robust, wide muzzle and thick jaw bones, with spoon–shaped teeth. As in Giraffatitan, there was an arch of bone over the snout and in front of the eyes that encircled the nasal opening, although this arch was not as large as in its relative. Large air sacs connected to the lung system were present in the neck and trunk, invading the vertebrae and ribs, greatly reducing the overall density. Unusually for a sauropod, the forelimbs were longer than the hind limbs. The humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....

 (upper arm bone) of Brachiosaurus was relatively lightly built for its size, measuring 2.04 metres (6.7 ft) in length in the type specimen. The femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

 (thigh bone) of the type specimen was only 2.03 metres (6.7 ft) long. Unlike other sauropods, Brachiosaurus appears to have been slightly sprawled at the shoulder joint, and the ribcage was unusually deep. This led to the trunk being inclined, with the front much higher than the hips, and the neck exiting the trunk at a steep angle. Overall, this shape resembles a giraffe more than any other living animal.

Size



Because "Brachiosaurus" brancai (Giraffatitan) is known from much more complete material than B. altithorax, most size estimates for Brachiosaurus are actually for the African form. There is an additional element of uncertainty for North American Brachiosaurus because the most complete skeleton appears to have come from a subadult. Over the years, the mass of B. altithorax has been estimated as 35 metric tons (38.6 ST), 43.9 metric tons (48.4 ST), and, most recently, 28.7 metric tons (31.6 ST). In the first and last cases, the authors also provided estimates for Giraffatitan, and found that genus to be somewhat lighter (31.5 metric tons (34.7 ST) for Paul [1988] and 23.3 metric tons (25.7 ST) for Taylor [2009]). The length of Brachiosaurus has been estimated at 26 metres (85.3 ft).

Classification


Brachiosaurus is the namesake genus of Brachiosauridae
Brachiosauridae
Brachiosauridae are a family of dinosaurs, whose members are known as brachiosaurids. They were herbivorous quadrupeds with longer forelegs than hind legs - the name derives from the Greek for arm lizard - and long necks...

. Over the years a number of sauropods have been assigned to Brachiosauridae, such as Astrodon
Astrodon
Astrodon was a genus of large herbivorous sauropod dinosaur, related to Brachiosaurus, that lived in what is now the eastern United States during the Early Cretaceous period. Its fossils have been found in the Arundel Formation, which has been dated through palynomorphs to the Aptian-Albian...

, Bothriospondylus
Bothriospondylus
Bothriospondylus is an dubious genus of sauropod dinosaur. It lived during the Late Jurassic.The type species, Bothriospondylus suffossus, was described by Richard Owen in 1875. The specific epithet suffossus means "undermined" in Latin, a reference to the fact that pleurocoels had hollowed out...

, Dinodocus
Dinodocus
Dinodocus is the name of a genus of sauropod dinosaur, named by Richard Owen in 1884. The name is now usually considered a nomen dubium. The only species, D...

, Pelorosaurus
Pelorosaurus
Pelorosaurus was a huge plant-eating dinosaur. Pelorosaurus was one of the first sauropod dinosaurs ever discovered. Pelorosaurus lived during the Early Cretaceous period, about 138-112 million years ago. Fossils referred to Pelorosaurus have been found in England and Portugal...

, Pleurocoelus, and Ultrasaurus
Ultrasaurus
Ultrasaurus is a genus of sauropod dinosaur discovered by Haang Mook Kim in South Korea. However, the name was first used unofficially in 1979 by Jim Jensen to describe a set of giant dinosaur bones he discovered in the United States...

, but most of these are currently regarded as dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...

 or of uncertain placement. A phylogenetic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

 of sauropods published in the description of Abydosaurus found that genus to form a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 with Brachiosaurus and Giraffatitan (included in Brachiosaurus). A more recent analysis focused on possible Asian brachiosaurid material found a clade including Abydosaurus, Brachiosaurus, Cedarosaurus
Cedarosaurus
Cedarosaurus was a nasal-crested macronarian dinosaur genus from the Early Cretaceous Period . It was a sauropod which lived in what is now Utah...

, Giraffatitan, and Paluxysaurus, but not Qiaowanlong
Qiaowanlong
Qiaowanlong is a genus of sauropod dinosaur. Fossils belonging to the genus were found in 2007 from the Yujinzi Basin of Gansu, China, and were described in 2009 in the Proceedings of the Royal Society B. The remains come from a geological formation called the Xinminpu Group, dating to the Early...

, the putative Asian brachiosaurid. Related genera include Lusotitan and Sauroposeidon
Sauroposeidon
Sauroposeidon is a genus of sauropod dinosaur known from four neck vertebrae that were found in the southeastern portion of the US state of Oklahoma. The fossils were found in rocks dating to the Early Cretaceous, a period when the sauropods of North America had diminished in both size and...

. Brachiosauridae is situated at the base of Titanosauriformes, a group of sauropods that also includes the titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...

s.

According to the revised diagnosis by Taylor Brachiosaurus altithorax is diagnosed by a plethora of characters, many to be found on the dorsal (back) vertebrae. Among the characters playing it in the family Brachiosauridae are a ratio of humerus to femur length greater or equal to 0.9 (i.e., the upper arm bone is at least nearly as long as the thigh bone), and a very flattened femur shaft (ratio ≥1.85).

Discovery and history



The genus Brachiosaurus, and type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

 B. altithorax, are based on a partial postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...

l skeleton from Fruita
Fruita, Colorado
The City of Fruita is a Home Rule Municipality located in the western part of Mesa County, Colorado, in the United States. It is part of the Grand Junction Metropolitan Statistical Area and within the Grand Valley...

, in the valley of the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

 of western Colorado. This specimen was collected from rocks of the Brushy Basin Member of the Morrison Formation in 1900
1900 in paleontology
-Newly named dinosaurs:Data coutersy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-New taxa:...

 by Elmer S. Riggs
Elmer S. Riggs
Elmer Samuel Riggs was an American paleontologist known for his work with the Field Museum of Natural History in Chicago, Illinois. He was born in Trafalgar, Indiana, and moved with his family to Kansas at a young age...

 and his crew from the Field Columbian Museum (now the Field Museum of Natural History
Field Museum of Natural History
The Field Museum of Natural History is located in Chicago, Illinois, USA. It sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex known as the Museum Campus Chicago...

) of Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

. It is currently cataloged as FMNH
Field Museum of Natural History
The Field Museum of Natural History is located in Chicago, Illinois, USA. It sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex known as the Museum Campus Chicago...

 P 25107. Riggs and company were working in the area as a result of favorable correspondence between Riggs and S. M. Bradbury, a dentist in nearby Grand Junction
Grand Junction, Colorado
The City of Grand Junction is the largest city in western Colorado. It is a city with a council–manager government form that is the county seat and the most populous city of Mesa County, Colorado, United States. Grand Junction is situated west-southwest of the Colorado State Capitol in Denver. As...

. In 1899 Riggs had sent inquiries to rural locations in the western United States concerning fossil finds, and Bradbury, an amateur collector himself, reported that dinosaur bones had been collected in the area since 1885. It was Riggs' field assistant H. W. Menke who found FMNH P 25107, on July 4, 1900. The locality, Riggs Quarry 13, was found on a small hill later known as Riggs Hill; it is marked by a plaque. Additional Brachiosaurus fossils are reported on Riggs Hill, but other fossil finds on the hill have been vandalized. Riggs published a short report in 1901, noting the unusual length of the humerus compared to the femur and the extreme overall size and the resulting giraffe-like proportions, as well as the lesser development of the tail, but did not publish a name for the new dinosaur. The titles of Riggs (1901) and (1903) suggested that the specimen was the largest known dinosaur. Riggs followed his 1903 publication that named Brachiosaurus altithorax with a more detailed description in a monograph
Monograph
A monograph is a work of writing upon a single subject, usually by a single author.It is often a scholarly essay or learned treatise, and may be released in the manner of a book or journal article. It is by definition a single document that forms a complete text in itself...

 in 1904.

The Fruita skeleton was not the first discovery of Brachiosaurus bones, although it was the first to be recognized as belonging to a new and distinct animal. In 1883, a sauropod skull was found near Garden Park
Garden Park, Colorado
Garden Park, in southcentral Colorado, is known for its Jurassic dinosaurs and the role the specimens played in the infamous bone wars of the late 19th century. Located north of Cañon City, Colorado, the name originates from the area providing vegetables to the miners at nearby Cripple Creek in...

, Colorado, at Felch Quarry 1, and was sent to Othniel Charles Marsh
Othniel Charles Marsh
Othniel Charles Marsh was an American paleontologist. Marsh was one of the preeminent scientists in the field; the discovery or description of dozens of news species and theories on the origins of birds are among his legacies.Born into a modest family, Marsh was able to afford higher education...

 (of "Bone Wars
Bone Wars
The Bone Wars, also known as the "Great Dinosaur Rush", refers to a period of intense fossil speculation and discovery during the Gilded Age of American history, marked by a heated rivalry between Edward Drinker Cope and Othniel Charles Marsh...

" fame). Marsh incorporated the skull into his skeletal restoration of "Brontosaurus" (now Apatosaurus
Apatosaurus
Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a...

). It eventually became part of the collections of the National Museum of Natural History
National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. Admission is free and the museum is open 364 days a year....

, as USNM 5730. In the 1970s, when Jack McIntosh and David Berman were working on the issue of the true skull of Apatosaurus, they reevaluated the Garden Park skull as more similar to Camarasaurus
Camarasaurus
Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America...

. It was described and recognized as a Brachiosaurus skull in 1998 by Kenneth Carpenter
Kenneth Carpenter
Kenneth Carpenter is a paleontologist. He is the museum director of the USU Eastern Prehistoric Museum and author or co-author of a number of books on dinosaurs and Mesozoic life...

 and Virginia Tidwell, intermediate in form
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 between Camarasaurus and Giraffatitan brancai (then still considered to be B. brancai). Because there are no overlapping parts between this skull and FMNH P 25107, it cannot be confidently assigned to a species, so it is classified as Brachiosaurus sp.

Additional discoveries of Brachiosaurus material in North America have been uncommon and consist of a handful of bones. Material has been described from Colorado, Oklahoma, Utah, and Wyoming, and undescribed material has been mentioned from several other sites. One of these specimens, a shoulder blade
Scapulocoracoid
The Scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula.The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions.The scapula is commonly known as the shoulder blade...

 from Dry Mesa Quarry
Dry Mesa Quarry
The Dry Mesa Dinosaur Quarry is situated in southwestern Colorado, USA, near the town of Delta. Its geology forms a part of the Morrison Formation and has famously yielded a great diversity of animal remains from the Jurassic Period, among them Ceratosaurus, Supersaurus, and Torvosaurus...

, Colorado, is one of the specimens at the center of the Supersaurus
Supersaurus
Supersaurus is a genus of diplodocid sauropod dinosaur discovered by Vivian Jones of Delta, Colorado, in the Upper Jurassic Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating to about 153 million years ago...

/Ultrasauros issue of the 1980s and 1990s. In 1985, James A. Jensen
James A. Jensen
James A. Jensen , was an American paleontologist. His extensive collecting program at BYU in the Utah-Colorado region which spanned 23 years was comparable in terms of the number of specimens collected to that of Barnum Brown during the early 20th century. He was given the name "Dinosaur Jim"...

 described disarticulated sauropod remains from the quarry as belonging to several taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

, including the new genera Supersaurus and Ultrasaurus, the latter renamed Ultrasauros shortly thereafter because another sauropod
Ultrasaurus
Ultrasaurus is a genus of sauropod dinosaur discovered by Haang Mook Kim in South Korea. However, the name was first used unofficially in 1979 by Jim Jensen to describe a set of giant dinosaur bones he discovered in the United States...

 already had the name. Later study showed that the "ultrasaur" material mostly belonged to Supersaurus, although the shoulder blade did not. Because the holotype of Ultrasauros, a back vertebra, was one of the specimens that was actually from Supersaurus, the name Ultrasauros is a synonym of Supersaurus. The shoulder blade is now assigned to Brachiosaurus, but the species is uncertain. In addition, the Dry Mesa "ultrasaur" was not as large as had been thought; the dimensions of the shoulder's coracoid bone indicate that the animal was smaller than Riggs' original specimen of Brachiosaurus.

Etymology


Riggs derived the genus name from the Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 brachion/βραχιων meaning "arm" and sauros/σαυρος meaning "lizard", because he realized that the length of the arms was unusual for a sauropod. The species epithet "altithorax" was chosen because of the unusually deep and wide chest cavity, from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 altus meaning "deep" and Greek thorax/θώραξ (Latin thorax), meaning "breastplate, cuirass, corslet".

Brachiosaurus altithorax



FMNH P 25107, the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 of both the genus Brachiosaurus and the species B. altithorax, consists of the right humerus (upper arm bone), the right femur (thigh bone), the right ilium
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...

 (a hip bone), the right coracoid (a shoulder bone), the sacrum (fused vertebrae of the hip), the last seven thoracic (trunk) and two caudal (tail) vertebrae, and a number of ribs. Riggs described the coracoid as from the left side of the body, but restudy has shown it to be a right coracoid.

Other assigned species

  • "B." atalaiensis: Originally described by de Lapparent
    Albert-Félix de Lapparent
    Albert-Félix de Lapparent was a French palaeontologist. He was also a Sulpician priest. He undertook a number of fossil-hunting explorations in the Sahara desert. He contributed greatly to our knowledge of dinosaurs and other prehistoric creatures...

     and Zbyszewski, this material's reference to Brachiosaurus was doubted by Upchurch, Barret and Dodson, who listed it as an unnamed brachiosaurid, and placed in its own genus Lusotitan
    Lusotitan
    Lusotitan is a genus of herbivorous brachiosaurid sauropod dinosaur from the Late Jurassic Period of Portugal.In 1947 by Manuel de Matos, collector of the Geological Survey of Portugal, fossils of a large sauropod were found in the Portuguese Lourinhã Formation dating to the Tithonian stage of the...

    by Antunes and Mateus. De Lapparent and Zbyszewski described a series of remains but did not designate a type specimen. Antunes and Mateus selected a partial postcranial skeleton (MIGM 4978, 4798, 4801–4810, 4938, 4944, 4950, 4952, 4958, 4964–4966, 4981–4982, 4985, 8807, 8793–87934) as a lectotype
    Lectotype
    In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...

    ; this specimen includes 28 vertebrae, chevrons
    Chevron (anatomy)
    A chevron is one of a series of bones on the ventral side of the tail in many reptiles, dinosaurs , and some mammals such as kangaroos and manatees....

    , ribs, a possible shoulder blade, humeri, forearm bones, partial left pelvis, lower leg bones, and part of the right ankle. The low neural spines, the prominent deltopectoral crest of the humerus (a muscle attachment site on the upper arm bone), the elongated humerus (very long and slender), and the long axis of the ilium tilted upward indicate that Lusotitan is a brachiosaurid.

  • "B." brancai: Janensch based his description on "Skelett S" (skeleton S) from Tendaguru, but later realized that it comprised two partial individuals: S I and S II. He did not designate them as a syntype series, nor specify a lectotype, and Taylor proposed the larger and more complete S II (MB.R.2181) as the lectotype. It includes, among other bones, several dorsal (trunk) vertebrae, the left scapula, both coracoids, both sternals (breastbones), both humeri, both ulna and radii (lower arm bones), a right hand, a partial left hand, both pubes
    Pubis (bone)
    In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....

     (a hip bone) and the right femur, tibia and fibula (shank bones). A re-assessment of the relation between the African and American brachiosaur material indicates that a separate generic name is warranted for the Tendaguru material, meaning that it now is considered to belong to Giraffatitan
    Giraffatitan
    Giraffatitan, meaning "giraffe titan", is a genus of sauropod dinosaur that lived during the late Jurassic Period . It was originally named as an African species of Brachiosaurus...

    .

  • "B." fraasi: erected by Janensch in 1914, but later synonomized with "B." brancai; this material now belongs to Giraffatitan.

  • "B." nougaredi: This species is known from fragmentary remains discovered in eastern Algeria
    Algeria
    Algeria , officially the People's Democratic Republic of Algeria , also formally referred to as the Democratic and Popular Republic of Algeria, is a country in the Maghreb region of Northwest Africa with Algiers as its capital.In terms of land area, it is the largest country in Africa and the Arab...

    , in the Sahara Desert. The present type material consists of a sacrum
    Sacrum
    In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...

     and some of the left metacarpals and phalanges
    Phalanx bones
    In anatomy, phalanx bones are those that form the fingers and toes. In primates such as humans and monkeys, the thumb and big toe have two phalanges, while the other fingers and toes consist of three. Phalanges are classified as long bones.The phalanges do not have individual names...

    . Found at the discovery site but not collected were partial bones of the left forearm, wrist bones, a right shin bone, and fragments that may have come from metatarsals
    Metatarsus
    The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...

    . de Lapparent, who described and named the material in 1960, reported the discovery locality as being in the Late Jurassic
    Late Jurassic
    The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...

    –age Taouratine Series (he assigned the rocks this age in part because of the presumed presence of Brachiosaurus), but more recent review assigns it to the "Continental intercalaire
    Kem Kem Beds
    The Kem Kem Beds is a geological formation in Morocco and Algeria whose strata date back to the Late Cretaceous...

    ," which is considered to be of Albian
    Albian
    The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...

     age (late Early Cretaceous
    Early Cretaceous
    The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...

    , significantly younger). This material was found disjointed over an area of several hundred meters. Upchurch, Barrett and Dodson (2004) doubted its assignment to Brachiosaurus, and listed it as an unnamed brachiosaurid. The sacrum is of notable size, with a length of 130 centimetres (51.2 in) for four vertebrae compared to 95 centimetres (37.4 in) for five vertebrae in B. altithorax; other bones are not of unusual size in comparison to B. altithorax or Giraffatitan brancai.

Referred material



Taylor (2009) lists a number of specimens referred to Brachiosaurus. These include some material, e.g., a humerus from Potter Creek and some Dry Mesa material (the latter partly described as Ultrasauros by Jensen), that are either clearly not brachiosaurid in origin, or at least not clearly referable to Brachiosaurus. In contrast, a cervical (neck) vertebra and the skull mentioned above may belong to either B. altithorax or an as-yet unknown brachiosaurid from North America. The cervical was found near Jensen, Utah, by Jensen, and – if it belongs to Brachiosaurus – is one of a handful of neck vertebrae known for American brachiosaurids. There is no unambiguous material of the skull, neck, anterior
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...

 dorsal (forward trunk) region, distal
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...

 (lower) limbs or feet.

There was ample material referred to "B." brancai in the collections of the Museum für Naturkunde Berlin, some of which was destroyed during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. Other material was transferred to other institution throughout Germany, some of which was also destroyed. Additional specimens are likely among the material collected by the British Museum of Natural History's Tendaguru expedition. Much or all of this material probably belongs to Giraffatitan, although some may represent a new brachiosaurid.

Separation from Giraffatitan


When describing the brachiosaurid material from Tendaguru in 1914, Janensch listed a number of differences and commonalities between them and B. altithorax. In three further publications in 1929, 1950
and 1961 Janensch compared the two species in more detail, listing 13 putative shared characters. Of these, however, only four appear to be valid, while six pertain to more inclusive groups than Brachiosauridae, and the rest are either difficult to assess or refer to material that is not Brachiosaurus.

In 1988, Gregory Paul published a new reconstruction of the skeleton of "B." brancai, highlighting a number of differences in proportion between it and B. altithorax. Chief among them is a difference in the way the trunk vertebrae vary: they are fairly uniform in B. altithorax, but vary widely in the African material. Paul believed that the limb and girdle elements of both species were very similar, and therefore suggested to separate them not at genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

, but only at subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...

 level.

Giraffatitan was raised to genus level by Olshevsky without comment. A detailed study of all material, including the limb and girdle bones, by Michael Taylor in 2009 found that there are significant differences between Brachiosaurus altithorax and the Tendaguru material in all elements known from both species. Taylor found 26 distinct osteological (bone-based) characters, a larger difference than that between, e.g., Diplodocus
Diplodocus
Diplodocus , or )is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek "double" and "beam", in reference to its double-beamed chevron bones...

and Barosaurus
Barosaurus
Barosaurus ; Greek barys/βαρυς meaning 'heavy' and saurus/σαυρος meaning 'lizard', 'heavy lizard') was a giant, long-tailed, long-necked, plant-eating dinosaur closely related to the more familiar Diplodocus...

, and therefore argued that the African material should be placed in its own genus, Giraffatitan, as G. brancai. An important difference between the two genera is the overall body shape, with Brachiosaurus having a 23% longer dorsal (trunk) vertebrate series and a 20 to 25% longer and also taller tail.

Paleoecology


With the removal of the East African Giraffatitan, Brachiosaurus is known only from the Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...

 of western North America. The Morrison Formation is interpreted as a semiarid environment with distinct wet
Wet season
The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...

 and dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...

s, and flat floodplain
Floodplain
A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

s. Vegetation varied from gallery forest
Gallery forest
Gallery forests are evergreen forests that form as corridors along rivers or wetlands and project into landscapes that are otherwise only sparsely treed such as savannas, grasslands or deserts....

s (river–lining forests in otherwise treeless settings) of conifers, tree ferns, and fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

s, to fern savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...

s with rare Araucaria
Araucaria
Araucaria is a genus of evergreen coniferous trees in the family Araucariaceae. There are 19 extant species in the genus, with a highly disjunct distribution in New Caledonia , Norfolk Island, eastern Australia, New Guinea, Argentina, Chile, and southern Brazil.-Description:Araucaria are mainly...

-like trees. Several other sauropod genera were present in the Morrison Formation, with differing body proportions and feeding adaptations. Among these were Apatosaurus
Apatosaurus
Apatosaurus , also known by the popular but scientifically deprecated synonym Brontosaurus, is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period . It was one of the largest land animals that ever existed, with an average length of and a...

, Barosaurus
Barosaurus
Barosaurus ; Greek barys/βαρυς meaning 'heavy' and saurus/σαυρος meaning 'lizard', 'heavy lizard') was a giant, long-tailed, long-necked, plant-eating dinosaur closely related to the more familiar Diplodocus...

, Camarasaurus
Camarasaurus
Camarasaurus meaning 'chambered lizard', referring to the hollow chambers in its vertebrae was a genus of quadrupedal, herbivorous dinosaurs. It was the most common of the giant sauropods to be found in North America...

, Diplodocus
Diplodocus
Diplodocus , or )is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek "double" and "beam", in reference to its double-beamed chevron bones...

, Haplocanthosaurus
Haplocanthosaurus
Haplocanthosaurus is a genus of sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period , 155 to 152 million years ago. The type species is H. priscus, and the referred species H...

, and Supersaurus
Supersaurus
Supersaurus is a genus of diplodocid sauropod dinosaur discovered by Vivian Jones of Delta, Colorado, in the Upper Jurassic Morrison Formation of Colorado in 1972. The fossil remains came from the Brushy Basin Member of the formation, dating to about 153 million years ago...

. Brachiosaurus was one of the less abundant Morrison Formation sauropods. In a survey of over 200 fossil localities, John Foster reported 12 specimens of the genus, comparable to Barosaurus (13) and Haplocanthosaurus (12), but far fewer than Apatosaurus (112), Camarasaurus (179), and Diplodocus (98). Brachiosaurus fossils are found only in the lower-middle part of the expansive Morrison Formation (stratigraphic zones 2-4), dated to about 154-153 million years ago, unlike many other types of sauropod which have been found throughout the formation.

Neck position


In contrast to most other sauropods, brachiosaurids had an inclined back, due to their long forelimbs. Therefore, if the neck exited the body in a straight line, it already pointed upwards. The exact angle is influenced by how the pectoral girdle is reconstructed, that is how the shoulder blades are placed on the ribcage. The mobility of the neck was reconstructed as quite low by Stevens and Parrish, while other researchers like Paul and Christian and Dzemski argued for more flexible necks.

Nostril placement



The placement of Brachiosaurus nostrils has been the source of much debate with Witmer (2001) describing in Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....

the hypothesized position of the fleshy nostrils in Brachiosaurus in as many as five possible locations.

There has also been the hypothesis of various sauropods, such as Brachiosaurus, possessing a trunk. The fact that there were no narrow-snouted sauropods (Brachiosaurus included) tends to discredit such a hypothesis. Stronger evidence for the absence of a trunk is found in the teeth wear of Brachiosaurus, which shows the kind of wear that would result from biting and tearing off of plant matter rather than purely grinding, which would be the result of having already ripped the leaves and branches off with its trunk.

Feeding ecology


Brachiosaurus is thought to have been a high browser
Browsing (predation)
Browsing is a type of herbivory in which an herbivore feeds on leaves, soft shoots, or fruits of high growing, generally woody, plants such as shrubs. This is contrasted with grazing, usually associated with animals feeding on grass or other low vegetation...

, feeding on foliage well above the ground. Even if it did not hold its neck near vertical, and instead had a straighter neck, its head height may still have been over 9 metres (29.5 ft) above the ground. It probably fed mostly on foliage above 5 metres (16.4 ft). This does not preclude the possibility that it also fed lower at times, between 3 to 5 m (9.8 to 16.4 ft) up. Its diet likely consisted of ginkgoes, conifers, tree ferns, and large cycads, with intake estimated at 200 to 400 kg (440.9 to 881.8 lb) of plant matter daily. However, more recent studies estimate that ~240 kilograms (529.1 lb) of plant matter would have been sufficient to feed a 70 metric tons (77.2 ST) sauropod, so Brachiosaurus may have required only about 120 kilograms (264.6 lb) of fodder a day. Brachiosaur feeding involved simple up–and–down jaw motion. The teeth were arranged to shear material as they closed, and were probably used to crop and/or nip vegetation.

It has repeatedly been suggested, e.g. in the movie Jurassic Park
Jurassic Park (film)
Jurassic Park is a 1993 American science fiction adventure film directed by Steven Spielberg. The film is based on the novel of the same name by Michael Crichton. It stars Sam Neill, Laura Dern, Jeff Goldblum, Richard Attenborough, Martin Ferrero, and Bob Peck...

, that Brachiosaurus could rear into a bipedal or tripodal (with tail support) pose to feed. However, a detailed physical modelling-based analysis of sauropod rearing capabilities by Heinrich Mallison showed that while many sauropods could rear, the unusual brachiosaurid body shape and limb length ratio made them exceptionally ill suited for rearing. The forward position of the center of mass would have led to problems with stability, and required unreasonably large forces in the hips to obtain an upright posture. Brachiosaurus would also have gained relatively little from rearing (only 33% more feeding height), compared to other sauropods, for which a bipedal pose may have tripled the feeding height.

Metabolism


Like all sauropods, Brachiosaurus was homeothermic
Warm-blooded
The term warm-blooded is a colloquial term to describe animal species which have a relatively higher blood temperature, and maintain thermal homeostasis primarily through internal metabolic processes...

 (maintaining a stable internal temperature) and endothermic
Endothermic
In thermodynamics, the word endothermic describes a process or reaction in which the system absorbs energy from the surroundings in the form of heat. Its etymology stems from the prefix endo- and the Greek word thermasi,...

 (controlling body temperature through internal means), meaning that it was able to actively control its body temperature, producing the necessary heat through a high basic metabolic rate
Basal metabolic rate
Basal Metabolic Rate , and the closely related resting metabolic rate , is the amount of daily energy expended by humans and other animals at rest. Rest is defined as existing in a neutrally temperate environment while in the post-absorptive state...

 of its cells. In the past, Brachiosaurus has been used an example of a dinosaur for which endothermy is unlikely, because of the combination of great size (leading to overheating) and great caloric
Calorie
The calorie is a pre-SI metric unit of energy. It was first defined by Nicolas Clément in 1824 as a unit of heat, entering French and English dictionaries between 1841 and 1867. In most fields its use is archaic, having been replaced by the SI unit of energy, the joule...

 needs to fuel endothermy. However, these calculations were based on incorrect assumptions about the available cooling surfaces (the large air sacs were not known), and a grossly inflated body mass. These inaccuracies resulted in overestimation of heat production and underestimation of heat loss. The large nasal arch has been postulated as an adaptation for cooling the brain, as a surface for evaporative cooling of the blood. Again, when this was proposed, cooling via the air sacs was not known, and thus not taken into account. Furthermore, other similar sized sauropods had no comparable structure. Additionally, in proportion to the entire animal, the nasal arch is very small, and would thus have made only an insignificant contribution to heat loss.

In culture




The original Brachiosaurus specimens collected by Elmer Riggs for the Field Museum of Natural History
Field Museum of Natural History
The Field Museum of Natural History is located in Chicago, Illinois, USA. It sits on Lake Shore Drive next to Lake Michigan, part of a scenic complex known as the Museum Campus Chicago...

 (Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

) were not put on display in the museum until 1994, when a skeletal mount (made up of resin casts rather than actual fossil bones) was constructed inside the museum's main Stanley Field Hall. The mount stood until 1999, when it was moved to the B Concourse of United Airlines
United Airlines
United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees (which includes the entire holding company United Continental...

' Terminal One in O'Hare International Airport
O'Hare International Airport
Chicago O'Hare International Airport , also known as O'Hare Airport, O'Hare Field, Chicago Airport, Chicago International Airport, or simply O'Hare, is a major airport located in the northwestern-most corner of Chicago, Illinois, United States, northwest of the Chicago Loop...

. At the same time, a second cast (in bronze) of the Field Museum's B. altithorax was constructed outside the museum.

Brachiosaurus is one of the best-known dinosaurs amongst both paleontologists and the general public. A main belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...

 asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

, , has been named 9954 Brachiosaurus
9954 Brachiosaurus
9954 Brachiosaurus is a main belt asteroid. It orbits the Sun once every 4.58 years.Discovered on April 8, 1991 by E. W. Elst, it was given the provisional designation "". It was later renamed "Brachiosaurus" after Brachiosaurus, a large herbivorous dinosaur.- References :...

 in honor of the genus. The genus has been featured in many films and television programs, most notably the Jurassic Park
Jurassic Park (film)
Jurassic Park is a 1993 American science fiction adventure film directed by Steven Spielberg. The film is based on the novel of the same name by Michael Crichton. It stars Sam Neill, Laura Dern, Jeff Goldblum, Richard Attenborough, Martin Ferrero, and Bob Peck...

and Walking with Dinosaurs
Walking with Dinosaurs
Walking with Dinosaurs is a six-part documentary television miniseries that was produced by BBC, narrated by Kenneth Branagh, and first aired in the United Kingdom, in 1999. The series was subsequently aired in North America on the Discovery Channel in 2000, with Branagh's voice replaced with that...

series. The digital model of Brachiosaurus used in Jurassic Park went on to become the starting point for the ronto models in the 1997 special edition of the science fiction film Star Wars Episode IV: A New Hope
Star Wars Episode IV: A New Hope
Star Wars Episode IV: A New Hope, originally released as Star Wars, is a 1977 American epic space opera film, written and directed by George Lucas. It is the first of six films released in the Star Wars saga: two subsequent films complete the original trilogy, while a prequel trilogy completes the...

.

External links