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Temporal range: Late Jurassic - Early Cretaceous, 157–93 Ma (Possible Late Cretaceous record)
|Mounted Brachiosaurus skeleton cast, Field Museum of Natural History|
Brachiosauridae is a family of sauropod 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. Despite their apparently distinctive features, there is some dispute as to whether Brachiosauridae is really a distinct family or a collection of basal Titanosauriformes. As a result, there is also some dispute about which animals belong within this family.
Some members of this clade are among the largest known dinosaurs and one of them (Brachiosaurus) was once thought to be the largest land animal ever to live. Brachiosaurids had unusually long and upright necks that gave them access to the leaves of treetops that would have been inaccessible to other sauropods. Their long and spatulate (spoon-shaped) teeth were capable of processing tougher plant material than some other sauropods (such as Diplodocus).
There are tentative reports of brachiosaurid remains from the latest Late Cretaceous, however the current consensus is that they disappeared in the late Early Cretaceous. Brachiosaurid fossils were first found in North America in the early 20th century, and it is now known that these dinosaurs found suitable habitats in Africa, Europe and probably Asia.
Traditionally, Brachiosauridae included Brachiosaurus and some other suggestively assigned genera, following the generic separation of Brachiosaurus species into B. altithorax and Giraffatitan brancai this have been the only members supported by cladistic analysis.
The fragmentary nature of most putative brachiosaurids have limited their exact position and support for inclusion in most cladistic analyses, however, a recent cladistic analysis (D'Emic, 2012) confirmed the assignment of some of these taxa (Cedarosaurus, Venenosaurus, Abydosaurus) while some of them were recovered outside the clade, Sauroposeidon (including Paluxysaurus) as part of somphospondyli, Qiaowanlong as part of Euhelopodidae and Atlasaurus outside Neosauropoda and found strong support for Europasaurus as a brachiosaurid, occupying a position as the most primitive member of the clade. Other previously suggested brachiosaurids like Daanosaurus and Lusotitan were not included in the analysis due to having a low ratio of available to preserved information, Bothriospondylus and Sonorasaurus were also not included in the analysis, the later because it shows features present in brachiosaurids, basal somphospondylans and basal titanosaurs and further data is needed to resolve its affinities.
Cladogram of Brachiosauridae after D'Emic (2012).
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