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''Polacanthus'', deriving its name from the Ancient Greek polys-/πολύς- "many" and akantha/ἄκανθα "thorn" or "prickle", is an early armoured, spiked, plant-eating ankylosaurian dinosaur from the early Cretaceous period of England. In the genus ''Polacanthus'' several species have been named but only the type species ''Polcanthus foxii'' is today seen as valid. ''Polacanthus'' was a quadrupedal ornithischian or "bird-hipped" dinosaur. It lived 130 to 125 million years ago in what is now western Europe.〔Holtz, Thomas R. Jr. (2011) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'' (Winter 2010 Appendix. )〕 ''Polacanthus foxii'' was named after a find on the Isle of Wight in 1865. There are not many fossil remains of this creature, and some important anatomical features, such as its skull, are poorly known. Early depictions often gave it a very generic head as it was only known from the rear half of the creature. It grew to about long. Its body was covered with armour plates and spikes. It possibly was a basal member of the Nodosauridae. ==Discovery and species== ''Polacanthus foxii'' was discovered by the Reverend William Fox on the Isle of Wight in 1865, at Barnes High at the southwest coast. Fox at first planned to have his friend Alfred Tennyson name the new dinosaur. Tennyson proposed ''Euacanthus Vectianus'' but this name was ultimately rejected.〔Tennyson, H., 1897, "Note about ''Polacanthus''", In: ''Alfred Lord Tennyson, A memoir by his son'', The MacMillan Company, p. 23-24〕 In 1865, Fox in a lecture to the British Association reported on the find and let it be named ''Polacanthus foxii'' by Richard Owen, hereby circumventing the convention that an author does not name a taxon after himself.〔Fox W. (1865). "On a new Wealden saurian named ''Polacanthus''". ''Report of the British Association for the Advancement of Science'', 1865 for 1864, p. 56〕 The text of the lecture was more or less reproduced by him in an anonymous article in the ''Illustrated London News''. This procedure caused some confusion as no corresponding 1865 publication by Owen exists. Some have therefore contended that Thomas Huxley in 1867 became the author of the name,〔Huxley, T.H., 1867, "On ''Acanthopholis horridus'', a new reptile from the Chalk Marl", ''Geological Magazine'', 4: 65-67〕〔 others give Fox, Owen or "Anonymous" as the author. The generic name is derived from Greek πολύς, ''polys'', "many" and ἄκανθα, ''akantha'', "thorn", in reference to the many spikes of the armour. The specific name honours Fox. The holotype, BMNH R175, was found in a layer of the Upper Wessex Formation dating from the Barremian. It is an incomplete skeleton with the head, neck, anterior armour and forelimbs missing but including dorsal vertebrae, the sacrum, most of the pelvis, most of the left hindleg, the right thighbone, twenty-two tail vertebrae, ribs, chevrons, ossified tendons, a pelvic shield, twenty-two spikes and numerous ossicles. The skeleton was in 1881 studied by John Whitaker Hulke, while it was still in the possession of Fox. Hulke published the first detailed description of the find, noting that the specimen had badly deteriorated over the years, the dermal armour having almost fully fallen apart.〔Hulke, J.W., 1881, "''Polacanthus foxii'', a large undescribed dinosaur from the Wealden Formation in the Isle of Wight", ''Philosophical Transactions of the Royal Society of London'', 172: 653–662〕 The same year Fox died, his collection was acquired by the British Museum of Natural History, including the ''Polacanthus'' fossil. This was then reassembled by preparator Caleb Barlow, painstakingly putting all the pieces together with Canada balsam, much to the wonder of Hulke who in 1881 had called this a hopeless undertaking. This allowed Hulke to redescribe the specimen in 1887, with a special attention to the armour arrangement.〔Hulke, J.W., 1887, "Supplemental Note on ''Polacanthus Foxii'', Describing the Dorsal Shield and Some Parts of the Endoskeleton, Imperfectly Known in 1881", ''Philosophical Transactions of the Royal Society of London. B'' 178: 169–172〕 In 1905, the specimen was again described by Franz Nopcsa who for the first time provided an illustration of the possible spike configuration.〔Nopcsa, F., 1905, "Notes on British dinosaurs. Part II. ''Polacanthus''", ''Geological Magazine'' 2: 241-250〕 Later it was realised that, at one occasion at least, even before 1865 probable ''Polacanthus'' fossils had been found. In 1843 John Edward Lee reported the discovery on Wight of two armour specimens.〔Lee, J.E., 1843, "Notice of Saurian Dermal Plates from the Wealden of the Isle of Wight", ''Annals And Magazine of Natural History'' 11: 5-7〕 Numerous specimens from Wight and Great Britain have since been referred to ''Polacanthus''. These mostly consist of single bones or armour elements. A second partial skeleton, from which parts had been removed since 1876, was identified and fully excavated by Dr William T. Blows in 1979; it is also in the London Natural History Museum as specimen NHMUK R9293. It is the first specimen to show skull elements, neck vertebrae and unequivocal anterior armour.〔Blows W.T. (1987). The armoured dinosaur ''Polacanthus foxi'', from the Lower Cretaceous of the Isle of Wight, Palaeontology. 30, 557–580〕 Several ankylosaurian remains from the Early Cretaceous of continental Europe have been referred to ''Polacanthus'' but none demonstrably share any unique traits, or autapomorphies, with its holotype. 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「Polacanthus」の詳細全文を読む スポンサード リンク
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