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''Sauroposeidon'' ( ; meaning "earthquake god lizard", after the Greek god Poseidon〔According to Wedel ''et al.'' (2005), the etymology of the name is based on Poseidon's association with earthquakes, not the sea.〕) is a genus of sauropod dinosaur known from several incomplete specimens including a bone bed and fossilized trackways that have been found in the American states of Oklahoma, Wyoming, and Texas. The fossils were found in rocks dating from near the end of the Early Cretaceous (Aptian-early Albian), a time when sauropod diversity in North America had greatly diminished. It was the last known North American sauropod prior to an absence of the group on the continent of roughly 40 million years that ended with the appearance of ''Alamosaurus'' during the Maastrichtian. While the holotype remains were initially discovered in 1994, due to their unexpected age and unusual size they were initially misclassified as pieces of petrified wood. A more detailed analysis in 1999 revealed their true nature which resulted in a minor media frenzy, and formal publication of the find the following year. Paleoecological analysis indicates that ''Sauroposeidon'' lived on the shores of the Gulf of Mexico, in a river delta. Extrapolations based on the more completely known ''Brachiosaurus'' indicate that the head of ''Sauroposeidon'' could reach in height with its neck extended, which would make it the tallest known dinosaur. With an estimated length of up to , height 15 m and mass of , it also ranks among the longest and heaviest. However, this animal may not be as closely related to ''Brachiosaurus'' as previously thought, so these estimates may be inaccurate. While initially described as a brachiosaurid closely related to ''Brachiosaurus'' and ''Giraffatitan'', the discovery of additional remains in the Cloverly Formation of Wyoming suggested that it was in fact more closely related to the titanosaurs, in the group Somphospondyli. Analysis of these remains and comparison with others from Texas supported this conclusion, and demonstrated that the more completely known sauropods from the Twin Mountains Formation (including a partial skull and fossil trackways) previously named ''Paluxysaurus jonesi'' also belonged to ''Sauroposeidon''.〔D'Emic, M.D. and B.Z. Foreman, B.Z. (2012). "The beginning of the sauropod dinosaur hiatus in North America: insights from the Lower Cretaceous Cloverly Formation of Wyoming." ''Journal of Vertebrate Paleontology'', 32(4): 883-902. 〕 ==Discovery== The first fossils classified as ''Sauroposeidon'' were four neck vertebrae discovered in rural Oklahoma, not far from the Texas border, in a claystone outcrop that dates the fossils to about 110 million years ago (mya). This falls within the Early Cretaceous Period, specifically between the Aptian and Albian epochs. These vertebrae were discovered in 1994 at the Antlers Formation in Atoka County, Oklahoma by Dr. Richard Cifelli and a team from the Oklahoma Museum of Natural History. Initially the fossils were believed to be simply too large to be the remains of an animal, and due to the state of preservation, believed to be tree trunks. In fact, they are the longest such bones known in dinosaurs. Thus, the vertebrae were stored until 1999, when Dr. Cifelli gave them to a graduate student, Matt Wedel, to analyze as part of a project. Upon their realization of the find's significance, they issued a press release in October 1999, followed by official publication of their findings in the ''Journal of Vertebrate Paleontology'' in March 2000. The new species was named ''S. proteles'', and the holotype is OMNH 53062. In 2012, numerous other sauropod remains that had been known for decades under various different names were also classified in the genus ''Sauroposeidon''.〔 Sauropod bones and trackways had long been known from the Paluxy River area of Texas, usually referred to the genus ''Pleurocoelus'', including partial skeletons (particularly from the Glen Rose Formation, above the Twin Mountains Formation). In the mid 1980s, students from the University of Texas at Austin discovered a bonebed on a ranch in Hood County, but early work stopped in 1987. The quarry was reopened in 1993 and was subsequently worked by parties from Southern Methodist University, the Fort Worth Museum of Science and History, and Tarleton State University. All sauropod remains from this bonebed appear to come from the same genus of sauropod. Petrified logs are also known from the site. The site was fluvial when its rocks were being deposited, with channel sands and muds, and concretions of calcite-cemented sandstone containing fossils. Following excavation and preparation of the majority of the fossils from the site, its sauropod species was given the name ''Paluxysaurus jonesi''. The name ''Paluxysaurus'' was based on the specimen FWMSH 93B-10-18, a partial skull including an associated left maxilla, nasal, and teeth. Other bones from the quarry included a partial neck of seven vertebrae, thirteen vertebrae from the back and 30 from the tail, and examples of all limb and girdle bones except some hand and foot bones. It was distinguished from all other sauropods by vertebral details, and has various morphological differences in other bones compared to other sauropods of the Early Cretaceous of North America. The genus was limited to the bonebed remains; for example, the partial skeleton from Wise County known as ''Pleurocoelus'' sp. (SMU 61732) is not referred to ''Paluxysaurus''; instead that specimen is the holotype of ''Astrophocaudia slaughteri'' D'Emic 2012, another somphospondylan sauropod. There are differences in the remains of ''P.'' sp. and ''Paluxysaurus'', but they cannot be distinguished with confidence.〔 In 2012, re-analysis of these specimens in light of additional ''Sauroposeidon'' remains led paleontologists D'Emic and Foreman to conclude that ''Paluxysaurus'' was the same animal as ''Sauroposeidon'', and thus a junior synonym of ''S. proteles''.〔 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「Sauroposeidon」の詳細全文を読む スポンサード リンク
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