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Author's note: these pages were written some years ago. I am not planning to update them. For a more current coverage, see the link to palaeos com Palaeos website (to which many links on these pages point to anyway. More info here


Family Brachiosauridae

link to palaeos com Middle Jurassic to link to palaeos com Middle Cretaceous
( link to palaeos com Bathonian to link to palaeos com Albian / link to palaeos com Cenomanian)

Brachiosaurus - life reconstruction
Brachiosaurus altithorax
illustration by Steve Kirk - Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals

Together with the Camarosaurs and Titanosaurs, the Brachiosaurs comprise clade Macronaria, one of the two main lineages of advanced Sauropods. The Brachiosaurus were a family of huge sauropods that includes some of the largest land animals. The brachiosaurs and their cousins, the camarosaurs, were distinguished by having forelimbs as long as or longer than their hind limbs, giving them high shoulders and a sloping back. This, and their long vertical necks, gave them a curiously giraffe-like appearance. They were high-grazers, able to feed on the leaves of trees too high for other sauropods to reach.They relied on sheer size as a defense against predators. These animals, are distinguished by their long necks and long arms. The best-known species is the Tanzanian Giraffatitan (more commonly known as Brachiosaurus), but many other species are also known. Generally, brachiosaurids have long arms relative to the hindlimbs and very long, upwards diagonally-held necks. They are the only dinosaurs with forelimbs longer than the hind, hence the name "Brachiosaurus" - arm lizard.

Giraffatitan skullAs with the camarasaurs the skull (left) is large, the teeth long and spatulate (spoon-shaped). The upper front of the lightly-constructed skull (the nasal bones) is highly vaulted, with large, elevated nares (nostril holes) indicating nostrils close to the top of the head. This led to several bizarre theories. One was that the animal hid from preditors at the bottom of deep lakes, feeding on water weeds and only poking its "snorkal" through the surface to breath. This is physiologically absurd, as water pressure would make breathing at such a depth impossible. The other theory is that brachiosaurs possessed an elephant-like trunk, as all mammals with trunks (tapirs, elephants, etc) have vaulted elevated nares. However, no reptile is known to have the facial muscles necessary for a trunk, and no indications of scars or blood-vessels have been found in any dinosaur indicating a trunk-like organ. A more plausible theory is that the inflated nares were a cooling mechanism. Living during the tropical hothouse conditions of the Jurassic, such enormous animals were in danger of overheating. Blood therefore was conveyed to the top of the head, where it was cooled via heat-exchange and perhaps also membranes of skin (african elephants use their large ears for the same purpose - the frozen remains of woolly mammoths show their ears were a lot smaller).

brachiosaur image (above) from Prof. Paul Olsen's external link Dinosaurs and the history of life - Geology V1001x pages

The neck was long and giraffe-like, with elongated individual vertebrae; the back also sloped ina giraffe-like fashion. These animals were, like the Camarasaurs, high browsers, and may indeed have been able to reach even higher branches than the camarasaurids could. Unlike the caamarasaurs the neural spines were undivided and small, and the neck, although large and stiff, was probably not equipped with the sort of powerful tendons Camarasaurs had, and could not have been held as erectly. Most reconstructions are in error in that they show the neck held in a very high, camarasaur-like posture.

The non-zonal fibro-lamellar bone structure indicates fast, uninterrupted growth from the baby to the adult stage, and these animals were perhaps fairly metabolically active (another reason for the vaulted nares as a heat sink.

With average lengths of 18 to 25 metres, and usual adult weights 15 to 45 tonnes (the largest species reaching 30 to 35 meters in length and perhaps 60 to 80 tonnes in weight), the Brachiosaurs were the largest animals of their time. Like the elephants of today, they were lords everything they surveyed. Not even Ceratosaurs, Allosaurs, or Torvosaurs, the top predators of the Jurassic, would think of taking on a full-grown brachiosaur, any more than a lion would mess with an adult elephant.

info panel

Guild/Ecological niche: gigantic terrestrial high browsing herbivores
Modern equivalent: elephant??? giraffe???
Time: link to palaeos com Bathonian to link to palaeos com Albian / link to palaeos com Cenomanian
Distribution: Worldwide
Evolved from: Cetiosauridae
Replaced: Cetiosauridae
Replaced by: Titanosaurs
Extinction because of: Cenomonian mass-extinction event
Descendents: none (or Camarasauridae from very early forms???)
Linnean status: Family
Cladistic status: Monophyletic clade
Parent clade: Macronaria
Adult length: 13 to 35 meters
Adult weight: 15 to 80 tonnes
Environment/Preferred habitat: seasonally dry floodplains, near large rivers and temporary ponds
Activity period: mostly diurnal, but probably fed and was active almost 24 hours
Metabolism: endothermic when young?, gigantotherms (homeotherms) when subadult and adult
Senses: Eyes large, facing sideways; very good all-round (≅270° ?) vision. Hearing and sense of smell moderate.
Intelligence: brain to weight ratio small, at low end of modern reptiles, consciousness guided largely by instinct
Preferred food: mainly conifers - foliage from middle and upper branches
Feeding behaviour: stood motionless or walked very slowly, sweeping neck and head in wide arcs to access all foliage within reach, leaves and twigs cut and crushed with teeth
Food Processing: food ground in gizzard; huge intestines with symbiotic microrganisms to process plant amterial
Social behavior: travelled in large, tightly-knit herds? Or some types herding (e.g. Giraffatitan) and others solitary (e.g. Brachiosaurus) depending on species?
Voice: Loud, mooselike bugle
Possible Life Cycle: quasi r-strategist, nest excavated with hind feet, eggs covered with dirt or vegetation, then abandoned, young small, active, high metabolism. Infant mortality high, but young very fast-growing, as they grew larger their metabolism and growth-rate slowed, slowed, became typical gigantotherms, joined the herd as "teenagers"
Movement: erect stance, slow plodding gait. Easily mired in mud. Unlikely to rear on hindlegs. Swimming ability poor; tail small and feet compact
Walking speed: probably about 3 or 4 kph
Running Speed: no more than 10 or 12 kph
Predators: none as healthy adult; young, sick, etc vulnerable to any large theropod
Defense against predators: height and good eyesight allowed early detection of predators; but not very aggressive when confronted as neck, tail, and bite weak; size in adult only defense, stomping on careless predators with forelegs, or kicking with hind-legs, also by keeping in a tight herd; for young very rapid growth and possible camoflague markings only protection.
Weaknesses: easily mired in mud or swamps; lack of defensive weaponry against predators

The following cladogram is a simplified version of the ones at Mikko's phylogeny site and Justin Tweet's Thescelosaurus! pages. I have also made the completely arbitrary assumption that the three species of Morrison Camarasaurs which suceed each other chronologically are also an evolutionary succession (a chronospecies so to speak). There are of course many more species than those listed in this diagram, but most of them are of questionable relationships.


<==o MACRONARIA ["BRACHIOSAURIA"]
   |--o Camarasauridae
   `-+-o Brachiosauridae Riggs, 1903a 
      |   `-+- Lapparentosaurus madagascariensis Bonaparte, 1986b
      |      `-+-- Atlasaurus imelakei Monbaron, Russell, and Taquet, 1999
      |         `-+-- Giraffatitan brancai (Janensch, 1914)
      |             |?-- Bothriospondylus suffosus Owen, 1875
      |             |?-- Pelorosaurus conybearei Mantell, 1850
      |             |?-- Cedarosaurus weiskopfae Tidwell, Carpenter, and Brooks, 1999
      |             |?-- Sonorasaurus thompsoni Ratkevich, 1998
      |             `-+-- Sauroposeidon proteles  Wadel, Cifelli & Sanders, 2000
      |                `--o Brachiosaurus Riggs, 1903a
      |                     |-- B. altithorax Riggs, 1903a
      |                     `-- B. atalaiensis Lapparent & Zbyszewski, 1957
       `--o Titanosauriformes

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Brothriospondylus madagascariensis Bonaparte, 1986b

Horizon: Isalo Formation, Majungar, Madagascar
Age: link to palaeos com Bathonian
Place: central link to palaeos com Gondwana
Length: 15 to 20 metres

Based on juvenile remains previosuly referred to the genus Bothriospondylus, this early species appears to be very similiar to, and perhaps a direct ancestor of Brachiosaurus. Like the approximately contemporary Atlasaurus this is a link to palaeos com Gondwanaland form, and it is possible that the Brachiosaurs evolved in central Gondwana; China being dominated by Shunosaurine and Europe by Cetiosaurine Cetiosaurids

Atlasaurus imelakei Monbaron, Russell, and Taquet, 1999

Horizon:Guettious Sandstones, Beni Mellal, Morocco
Age: late link to palaeos com Bathonian
Place:(northern central link to palaeos com Gondwana)
Humerus 1.37 metres; femur 1.60 metres [Steel, p.64]
Overall length about: 13 to 14 meters

Comments: Originally called "Cetiosaurus" mogrebiensis, Atlasaurus imelakei is one of the earliest and most primitive of the brachiosaurs.

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Bothriospondylus suffosus Owen, 1875

Age: late link to palaeos com Oxfordian-early link to palaeos com Kimmeridgian
Place: European Islands (England and ?France)
remains: back and hip verebrae
Length: 17.5 meters
weight: around 17 tonnes, or possibly less

Comments: Not particularly well known, this sauropod appears to be closely related to Brachiosaurus

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Brachiosaurus atalaiensis Lapparent & Zbyszewski, 1957

Horizon: Unnamed unit, Provincia do Estremadura, Portugal
Age: Middle link to palaeos com Kimmeridgian
Place: European Islands (Portugal)

Comments: The huge B. atalaiensis was probably a descendent of the earlier link to palaeos com Kimmeridgian "Ornithopsis" leedsi. Like the contemporary Tendaguru Brachiosaurus (Giraffititan) brancai this was a slender animal.

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Brachiosaurus (Giraffatitan) brancai Janensch, 1914

Synonyms: Brachiosaurus brancai Janensch, 1914, Brachiosaurus fraasi Janensch, 1914
Horizon: Lower and Middle Saurian Bed, Tendaguru Beds, Mtwara, Tanzania
Age: Early to Middle link to palaeos com Kimmeridgian
Place: Central link to palaeos com Gondwana
remains: 5 partial skeltons, more than 3 skulls; altogether postcranial elements of at least 34 individuals
Brachiosaurus (Giraffatitan) brancai
size of selected skeletal elements
Size in metreshumerus
(upper arm)
ulna
(lower arm)
scapula
(shoulder balde)
femur
(thigh bone)
Fair-sized individual1.60 m1.01 m1.45 m1.55 m
Large individual
[in Berlin Museum]
2.13 m1.28 m2 m 

Left, a sketch of the famous Berlin Museum Brachiosaur; this is the tallest skeleton ever mounted. It is actually a composite of a number of specimens. Note - the position of the neck in this sketch is very unrealistic, the neck would actually have been held at a 45o angle

image from Prof. Paul Olsen's Dinosaurs and the history of life - Geology V1001x site

overall size of complete animal

overall size (metres)Overall LengthShoulder HeightHead HeightEstimated weight (tonnes)
Fair-sized individual18 m  14.9 t
Large individual
[in Berlin Museum]
22.2 m6.0 m14.0 m31.5 t
Very large individual
[partial skeleton]
25.0 m6.79 m18 m45 t

Comments: Originally considered to be a species of Brachiosaurus, Giraffatitan is now generally placed in its own genus, although it may or may not be a subgenus of Brachiosaurus. It differs from the American Brachiosaurus altithorax in its more gracile build and different form of neck vertebrae. Most representations of Brachiosaurus are actually based on this species, which isknown from more and more complete remains than any other brachiosaurid. It is a long-armed taxon based on a partial postcranial and larger individuals are known. The skull has an unusually tall rounded crest containing the nostrils.

The Giraffatitan brachiosaurs were gigantic terrestrial herbivores, "giraffe-elephants" adapted to feeding on the crowns of trees. They dominated the Tendaguru megafauna, making up about 27% of all large animals (in terms of numbers of individuals identified in the Middle Saurian Bed), but in terms of actual biomass that figure would be closer to 78%. The large numbers would seem to indicate herding behaviour (like Camarasaurs in the Morrison) The whole fauna could be rightfully called a Brachiosaur fauna. The only other identified sauropods were the small Dicraeosaurs and Barosaurs, both in the vicinity of three to four and a half tonnes, and grasers upon lowlying and (in the case of Barosaurus) medium-height vegetation.


Brachiosaurus (Brachiosaurus) altithorax Riggs, 1903a Horizon: Upper Morrison formation, Colorado and Utah
Age: Early link to palaeos com Tithonian
Place: western link to palaeos com Laurasia
remains: two partial skeletons, also an old skull has recently been shown to belong to this species.
Length: 22 to 27 metres or more
Weight: 25 to 45 or 50 tonnes

Comments: A more heavily built species than the slightly earlier Giraffatitan, this species is similar, but less well known. Most restorations are actually based on Giraffatitan. This was one of the largest animals ever to live. The so-called "Ultrasaurus" and "Supersaurus" are actually based on partial remains of giant Brachiosaurs (in the case of Supersaurus mixed up with other species). B. altithorax did not seem to be as common as G. brancai, which may indicate a siolitary behaviour, in contrast to the herding Giraffititan. Alternatively, the rarety may be dues to local preservation and environmental factors; perhaps altithorax frequented areas taht were not conducive to fossilisation

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Sonorasaurus thompsoni Ratkevich, 1998

Age: latest link to palaeos com Albian
Place: Western link to palaeos com Laurasia (Arizona); Cashenranchian Fauna
remains: skull and partial skeleton
Length: length 14? to 17? meters

Comments: A "pygmy" brachiosaurid, this animal nevertheless shows strong similarities with its larger Jurassic cousins.

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Pelorosaurus conybearei Mantell, 1850

Synonyms: Pelerosaurus, Pelosaurus, Pelrorosaurus, Polorosaurus, Telorosaurus
Age: link to palaeos com Barremian
Place: European Islands (England), Central link to palaeos com Laurasia

Comments: known from assorted postcrania, and skin-impresisons showing small, hexagon-like tubercles, Pelorosaurus a poorly known, fairly typical brachiosaurid, somewhat smaller than its Jurassic counterparts. A number of specimens assigned to this genus have been placed elsewhere, or are considered too fragmentary to identify properly.

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Cedarosaurus weiskopfae Tidwell, Carpenter, and Brooks, 1999

Horizon: Yellow Cat member of the Cedar Mountain Formation, Utah
Age: link to palaeos com Barremian
Place: Western link to palaeos com Laurasia (Utah); Cashenranchian Fauna
remains: partial skeleton.

Comments: Some material referred to Pleurocoelus (but not the type material) may belong here. "Pleurocoelus" (Hollow Side) is a name given to a number of smallish (8 or 10 meters) early Cretaceous American brachiosaurs known from the Arundal formation of Maryland. Astrodon (Star Tooth) is a synonym. Pleurocoelus altus was once thought to be the adult form of P. nanus, but more recently is has been suggested as an entirely different sauropod. The proportionately large pleurocoels of the Arundel type material is likely to be a juvenile trait; juvenile Camarasaurus material was once identified as Pleurocoelus because of the very large pleurocoels. It is likely the genus, like so many partial dinosaur remains, the Pleurocoelus may eventually turn out to be invalid, i.e. nomen dubum (that is, it is sauropod and apparently brachiosaur but not complete enough to diagnose further) and may be assigned other genera. To confuse matters even further, it has recently been suggested that Cedarosaurus and some of the Pleurocoelus material is not even brachiosaurian, but titanosaur instead.

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Brachiosaurus and Sauroposeidon
image from Oklahoma Museum of Natural History

Sauroposeidon proteles Wedel, Cifelli, and Sanders, 2000

Age: late link to palaeos com Aptian-early link to palaeos com Albian
Place: Western link to palaeos com Laurasia (Oklahoma); Cashenranchian Fauna
remains: rib, cervical vertebrae
Length: 30 to 35 metres
Weight: around 60 to 80 tonnes

Comments: Currently holding the status of the largest dinosaur ever (although the late Cretaceous titanosaur Argentinosaurus was certainly just as large), this enormous creature is known from four tree-trunk sized cervicals, and had the longest neck of any known animal, possibly twelve meters in length. It could have stood upto 18 meters tall. The drawing shows the comparison with a standard Brachiosaurus.

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Web links Links Web links

cladogram Brachiosauridae - Thescelosaurus!

links link to palaeos com Brachiosauridae - Palaeos

ABCNEWS.com: Dino May Have Been Tallest about Sauroposeidon

Dinosauricon Dinosauricon

cladogram Brachiosauridae Mikko's phylogeny site

printed reference Bob Bakker, "Bakker's field guide to Jurassic Park dinosaurs". pp.33-43, Earth September 1993

printed reference D.Russell, P. Béland, & J.S.McIntosh, "Paleoecology of the dinosaurs of Tendaguru (Tanzania)" in  Ecosystèmes Continentaux du Mésozoïque, Mémoires de la Société Géologique de France, 1980, no.139, pp.169-175.

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