/bray"kee euh sawr', brak"ee-/, n.
a huge sauropod dinosaur of the genus Brachiosaurus, having a small head with nostrils on a knob above the eyes, long forelegs, and a sloping, massive body, and reaching a length of about 80 ft. (24 m).
[ < NL Brachiosaurus (1903); see BRACHIO-, -SAUR; so named in allusion to the unusual length of the humerus relative to the femur]

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 any member or relative of the dinosaur genus Brachiosaurus, which lived 150 million to 130 million years ago from the Late Jurassic (Jurassic Period) to the Early Cretaceous Period. Brachiosaurs were the heaviest and tallest sauropod dinosaurs for which complete skeletons exist; larger fossil bones belonging to other (and possibly related) sauropods have been found, but these specimens are incomplete. Fossilized remains of brachiosaurs are found in Africa, North America, and Europe.

      Brachiosaurs were built like huge giraffes; they had immensely long necks and relatively short tails. Their morphology is unusual among dinosaurs in that the forelimbs were longer than the hind limbs. These adaptations apparently enabled them to lift their heads to about 12 metres (39 feet) above the ground in order to browse the branches of tall trees. Brachiosaurs attained a maximum length approaching 25 metres and a weight of nearly 80 metric tons. Their nasal bones were expanded into a broad arch that presumably allowed them to maintain some distance between the vegetation and the nasal openings so that they could breathe easily while feeding. The mouth contained a few dozen pencil-like teeth with beveled edges. Like most other dinosaurs, brachiosaurs did not chew their food but used their jaws to collect food, which the tongue presumably forced into the throat. Considering their massive size, their small heads, and the relatively poor quality of their forage, scientists have inferred that brachiosaurs must have spent nearly all their waking hours feeding.

      The huge size of brachiosaurs led some researchers to suggest that they spent most of their time submerged in water, which would have served to buoy up their great weight. The location of the nasal openings—on top of the head and above the eyes—lent additional support to this idea. However, water pressure at the depths needed to cover these dinosaurs would have crushed their lungs and thus made breathing difficult or impossible. Other features of their skeleton show that brachiosaurs were well adapted to a life spent on land browsing the high treetops. Their skeletons were strong but not massive, so their weight could be supported without any help from water. Their great neckbones, for example, are so deeply excavated that they function as a lightweight framework of struts and plates.

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Universalium. 2010.

Look at other dictionaries:

  • brachiosaur — [brā΄kē ə sôr′əsbrā′kē ə sôr΄, brak′ēə sôr΄] n. [< ModL Brachiosaurus < Gr brachiōn, an arm + sauros, lizard] any of a genus (Brachiosaurus) of huge Jurassic sauropods having longer forelegs than hind legs and nostrils high on the forehead …   English World dictionary

  • brachiosaur — noun Etymology: New Latin Brachiosaurs, from brachi + Greek sauros lizard Date: 1903 any of a genus (Brachiosaurus) of very large sauropod dinosaurs of the late Jurassic period having a massive body, a very long neck, and forelegs longer than… …   New Collegiate Dictionary

  • brachiosaur — noun Any of several massive, herbivorous sauropod dinosaurs, of the genus Brachiosaurus, from the Jurassic and Cretaceous periods …   Wiktionary

  • brachiosaur — brach·i·o·saur …   English syllables

  • brachiosaur — bra•chi•o•saur [[t]ˈbreɪ ki əˌsɔr, ˈbræk i [/t]] n. pal a sauropod dinosaur of the genus Brachiosaurus, having nostrils on a knob above the eyes and a sloping, massive body, and reaching a length of about 80 ft. (24 m) • Etymology: < NL… …   From formal English to slang

  • brachiosaur — /ˈbrækiəsɔ/ (say brakeeuhsaw) noun one of the Brachiosaurus, a genus of large dinosaurs of the Upper Jurassic period …   Australian English dictionary

  • brachiosaur — ˈbrakēōˌsȯ(ə)r noun ( s) Etymology: New Latin Brachiosaurus : a dinosaur of the genus Brachiosaurus …   Useful english dictionary

  • dinosaur — /duy neuh sawr /, n. 1. any chiefly terrestrial, herbivorous or carnivorous reptile of the extinct orders Saurischia and Ornithischia, from the Mesozoic Era, certain species of which are the largest known land animals. 2. something that is… …   Universalium

  • Museum für Naturkunde — Coordinates: 52°31′48″N 13°22′46″E / 52.530020°N 13.379514°E / 52.530020; 13.379514 …   Wikipedia

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