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bone bed
A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections. It is also applied to brecciated and stalagmitic deposits on the floor of caves, which frequently contain osseous remains.
In a more restricted sense, the term is used to connote certain thin layers of bony fragments, which occur in well-defined geological strata. One of the best-known of these is the Ludlow Bone Bed, which is found at the base of the Downton Sandstone in the Upper Ludlow series. At Ludlow (England) itself, two such beds are actually known, separated by about . of strata. Although quite thin, the Ludlow Bone Bed can be followed from that town into Gloucestershire, for a distance of . It is almost completely made up of fragments of spines, teeth and scales of ganoid fish. Another well-known bed, formerly known as the Bristol or Lias Bone Bed, exists in the form of several thin layers of micaceous sandstone, with the remains of fish and saurians, which occur in the Rhaetic Black Paper Shales that lie above the Keuper marls, in the south-west of England. It is noteworthy that a similar bone bed has been traced on the same geological horizon in Brunswick, Hanover (Germany), in Franconia and in Tübingen (Germany).〔Johannes Baier: ''Das Tübinger "Rhätolias-Grenzbonebed" ''. - Fossilien 31(1), 26-30, 2014.〕〔Johannes Baier: (''Der Geologische Lehrpfad am Kirnberg (Keuper; SW-Deutschland)'' ). - Jber. Mitt. oberrhein. geol. Ver, N. F. 93, 9-26, 2011.〕 A bone bed has also been observed at the base of the Carboniferous limestone series, in certain parts of the south-west of England.〔
Bone beds are also recorded in North America, South America, Mongolia and China. Terrestrial bonebed examples are: the Triassic ''Metoposaurus'' bone bed from Portugal,〔Brusatte, S. L., Butler R. J., Mateus O., & Steyer S. J. (2015). A new species of Metoposaurus from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls. Journal of Vertebrate Paleontology, e912988., 2015〕 the ''Mapusaurus'' bone bed at Canadon de Gato, in Argentina, the ''Allosaurus''-dominated Cleveland Lloyd Dinosaur Quarry of Utah, the Dinosaur National Monument on the boundary of Utah and Colorado, an ''Albertosaurus'' bone bed from Alberta, a ''Daspletosaurus'' bone bed from Montana, the Cenozoic John Day Fossil Beds of Oregon and the Nemegt Basin in the Gobi Desert region of Mongolia. Examples of marine bonebeds: Bentiaba, Angola〔Strganac, C., Jacobs L., Polcyn M., Mateus O., Myers T., Araújo R., Fergunson K. M., Gonçalves A. O., Morais M. L., Schulp A. S., da Tavares T. S., & Salminen J. (2014). Geological Setting and Paleoecology of the Upper Cretaceous Bench 19 Marine Vertebrate Bonebed at Bentiaba, Angola. Netherlands Journal of Geosciences. 1-16.〕 with numerous mosasaurs and plesiosaurs.
==References==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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