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Titanosaurs (members of the group Titanosauria) 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 ''Puertasaurus'', which are estimated to have weighed up to 90 tonnes (100 short tons). The group's name refers to the much earlier discovery ''Titanosaurus'', a now dubious genus named for the mythological Titans of Ancient Greece. Together with the brachiosaurids and relatives, titanosaurs make up the larger clade Titanosauriformes. ==Description== Titanosaurs had small heads, even when compared with other sauropods. The head was also wide, similar to the heads of ''Camarasaurus'' and ''Brachiosaurus'' but more elongated. Their nostrils were large ('macronarian') and they all had crests formed by these nasal bones. Their teeth were either somewhat spatulate (spoon-like) or like pegs or pencils, but were always very small. Their necks were of average length, for sauropods, and their tails were whip-like, but not as long as in the diplodocids. While the pelvis (hip area) was slimmer than some sauropods, the pectoral (chest area) was much wider, giving them a uniquely 'wide-gauged' stance. As a result, the fossilised trackways of titanosaurs are distinctly broader than other sauropods. Their forelimbs were also stocky, and often longer than their hind limbs. Their vertebrae (back bones) were solid (not hollowed-out), which may be a throwback to more primitive saurischians. Their spinal column was more flexible, so they were probably more agile than their cousins and better at rearing up. From skin impressions found with the fossils, it has been determined that the skin of many titanosaur species was armored with a small mosaic of small, bead-like scales around a larger scale. One species, ''Saltasaurus'', has even been discovered with bony plates, like the ankylosaurs. Studies published in 2011 also indicate that titanosaurs such as ''Rapetosaurus'' (on which the examinations were performed), may have used the osteoderms common in the various genera for storing minerals during harsh changes in climate, such as drought.〔http://phenomena.nationalgeographic.com/2011/12/02/titan-dinosaur-may-have-stored-minerals-in-skin-bones/〕〔http://www.earthtimes.org/nature/osteoderms-storing-minerals-helped-huge-dinosaurs-survive/1671/〕 While they were all huge, many were fairly average in size compared with the other giant dinosaurs. There were even some island-dwelling dwarf species such as ''Magyarosaurus'', probably the result of allopatric speciation and insular dwarfism. Derived titanosaurs had biconvex vertebrae.〔 The primitive condition is either amphiplaty or amphicoely.''〔 Venenosaurus'' may have had a condition intermediate between the two.〔Tidwell, V., Carpenter, K. & Meyer, S. 2001. New Titanosauriform (Sauropoda) from the Poison Strip Member of the Cedar Mountain Formation (Lower Cretaceous), Utah. In: Mesozoic Vertebrate Life. D. H. Tanke & K. Carpenter (eds.). Indiana University Press, Eds. D.H. Tanke & K. Carpenter. Indiana University Press. 139-165.〕 The remains of an unnamed Patagonian titanosaur found in Argentina in 2014 are from an animal estimated to have been 40 m (130 ft) long and 20 m (65 ft) tall, with an estimated weight of 77 tonnes, making it among the largest identified land animals in Earth's history. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Titanosaur」の詳細全文を読む スポンサード リンク
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