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''Hylaeosaurus'' ( ; Greek: hylaios/ὑλαῖος "belonging to the forest" and sauros/σαυρος "lizard") is a herbivorous ankylosaurian dinosaur that lived about 136 million years ago, in the late Valanginian stage of the early Cretaceous period of England. ''Hylaeosaurus'' was one of the first dinosaurs to be discovered, in 1832 by Gideon Mantell. In 1842 it was one of the three dinosaurs Richard Owen based the Dinosauria on. Four species were named in the genus, but only the type species ''Hylaeosaurus armatus'' is today considered valid. Only limited remains have been found of ''Hylaeosaurus'' and much of its anatomy is unknown. It might have been a basal nodosaurid. ''Hylaeosaurus'' was about five metres long. It was an armoured dinosaur. It carried at least three long spines on its shoulder and shorter spines at the side of its neck. ==History of discovery== The first ''Hylaeosaurus'' fossils were discovered in West Sussex. On 20 July 1832, fossil collector Gideon Mantell wrote to Professor Benjamin Silliman that when a gunpowder explosion had demolished a quarry rock face in Tilgate Forest, several of the boulders freed showed the bones of a saurian. A local fossil dealer had assembled the about fifty pieces, described by him as a "great consarn of bites and boanes". Having doubts about the value of the fragments, Mantell had nevertheless purchased the pieces and soon discovered they could be united into a single skeleton, partially articulated. Mantell was delighted with the find because previous specimens of ''Megalosaurus'' and ''Iguanodon'' had consisted of single bone elements. The discovery in fact represented the most complete non-avian dinosaur skeleton known at the time. He was strongly inclined to describe the find as belonging to the latter genus, but during a visit by William Clift, the curator of the Royal College of Surgeons of England museum, and his assistant John Edward Gray, he began to doubt the identification. Clift was the first to point out that several plates and spikes were probably part of a body armour, attached to the back or sides of the rump.〔Dennis R. Dean, 1999, ''Gideon Mantell and the Discovery of Dinosaurs'', Cambridge University Press, 315 pp〕 In November 1832 Mantell decided to create a new generic name: ''Hylaeosaurus''. It is derived from the Greek ὑλαῖος, ''hylaios'', "of the wood". Mantell originally claimed the name ''Hylaeosaurus'' meant "forest lizard", after the Tilgate Forest in which it was discovered.〔Mantell, Gideon Algernon, 1833, "Observations on the remains of the Iguanodon, and other fossil reptiles, of the strata of Tilgate Forest in Sussex", ''Proceedings of the geological Society of London'', 1: 410-411〕 Later, he claimed that it meant "Wealden lizard" ("wealden" being another word for ''forest''), in reference to the Wealden Group, the name for the early Cretaceous geological formation in which the dinosaur was first found.〔Mantell, G.A., 1838, ''The Wonders of Geology or a Familiar Exposition of Geological Phenomena'', 2 vols, Relfe and Fletcher, London〕 On 30 November Mantell sent the piece to the Geological Society of London. Shortly afterwards he himself went to London and on 5 December during a meeting of the Society, in which he for the first time personally met Richard Owen, reported on the find to large acclaim. However, he was also informed that a paper he had already prepared, was a third too long. On advice of his friend Charles Lyell, Mantell decided instead of rewriting the paper, to publish an entire book on his fossil finds and dedicate a chapter to ''Hylaeosaurus''. Within three weeks Mantell composed the volume from earlier notes. On 17 December Henry De la Beche warned him that the changed conventions in nomenclature implied that only he who provided a full species name was recognised as the author: to ''Hylaeosaurus'' a specific name needed to be added.〔 Mantell on 19 December chose ''armatus'', Latin for "armed" or "armoured", in reference to the spikes and armour plates. As Mantell himself put it: "there appears every reason to conclude that either its back was armed with a formidable row of spines, constituting a dermal fringe, or that its tail possessed the same appendage". In May 1833 his ''The Geology of the South-East of England'' appeared, hereby validly naming the type species ''Hylaeosaurus armatus''. Mantell published a lithograph of his find in ''The Geology of the South-East of England'';〔G.A. Mantell. 1833. ''The Geology of the South-East of England''. Longman Ltd., London〕 and another drawing in the fourth edition of ''The Wonders of Geology'', in 1840. Mantell perhaps already had described some remains of ''Hylaeosaurus'' prior to 1832, referring some possible teeth to "Cylindricodon", itself not originally a genus name but short for ''Phytosaurus cylindricodon'' Jaeger 1828. Even if the reference were to be considered the first naming of a genus "Cylindricodon", this would not be a valid senior synonym of ''Hylaeosaurus'' as the teeth were insufficiently described and their identity is dubious. ''Hylaeosaurus'' is the most obscure of the three animals used by Sir Richard Owen to first define the new group Dinosauria, in 1842, the other genera being ''Megalosaurus'' and ''Iguanodon''. Not only has ''Hylaeosaurus'' received less public attention, despite being included in the life-sized models by Benjamin Waterhouse Hawkins placed in the Crystal Palace Park, it also never functioned as a "wastebasket taxon". Owen in 1840 developed a new hypothesis about the spikes; noting they were asymmetrical he correctly rejected the notion they formed a row on the back but incorrectly assumed they were gastralia or belly-ribs. The original specimen, recovered by Gideon Mantell from the Tilgate Forest, was later acquired by the Natural History Museum of London. It has the inventory number NHMUK 3775 (earlier BMNH R3775). It was found in a layer of the Grinstead Clay Formation dating from the Valanginian, about 137 million year old. This holotype is the best specimen and is composed of the front end of a skeleton minus most of the head and the forelimbs, though only the parts on the face of the stone block are easily studied. The block measures about 135 by 75 centimetres. The holotype consists of the rear of the skull and perhaps lower jaws, ten vertebrae, both scapulae, both coracoids and several spikes and armour plates. The skeleton is viewed from below. For a long time no further preparation had taken place, beyond the assembly and chiselling out by Mantell himself, but in the early twenty-first century the museum began to further free the bones by both chemical and mechanical means.〔Naish, D. & Martill, D.M., 2008, "Dinosaurs of Great Britain and the role of the Geological Society of London in their discovery: Ornithischia", ''Journal of the Geological Society, London'' 165: 613-623〕 The information gained hereby has not yet been published. Several finds from the mainland of Britain have been referred to ''Hylaeosaurus armatus''.〔Pereda-Suberbiola, J., 1993, "''Hylaeosaurus'', ''Polacanthus'', and the systematics and stratigraphy of Wealden armoured dinosaurs", ''Geological Magazine'' 130(6): 767-781〕〔Barrett, P.M., 1996, "The first known femur of ''Hylaeosaurus armatus'' and reidentification of ornithopod material in The Natural History Museum, London", ''Bulletin of the Natural History Museum (Geology)'', 52: 115–118〕 However, in 2011 Paul Barrett and Susannah Maidment concluded that only the holotype could with certainty be associated with the species, in view of the presence of ''Polacanthus'' in the same layers.〔Barrett, P.M. and Maidment, S.C.R., 2011, "Wealden armoured dinosaurs". In: Batten, D.J. (ed.). ''English Wealden fossils''. Palaeontological Association, London, Field Guides to Fossils 14, 769 pp〕 Additional remains have been referred to ''Hylaeosaurus'', from the Isle of Wight, (the Ardennes of) France,〔Corroy, G., 1922, "Les reptiles néocomiens et albiens du Bassin de Paris", ''Comptes Rendus de l’Académie des Sciences de Paris'' 172: 1192–1194〕 Germany,〔Koken, E., 1887, "Die Dinosaurier, Crocodiliden und Sauropterygier des norddeutschen Wealden", ''Geologische und Palaeontologische Abhandlungen'' 3: 311–420〕 Spain〔Sanz, J.L., 1983, "A nodosaurid ankylosaur from the Lower Cretaceous of Salas de los Infantes (Province of Burgos, Spain)", ''Geobios'', 16: 615-621〕 and Romania.〔E. Posmosanu, 2003, "The palaeoecology of the dinosaur fauna from a Lower Cretaceous bauxite deposit from Bihor (Romania)". In: A. Petculescu & E. Stiuca (eds.), ''Advances in Vertebrate Paleontology: Hen to Panta''. Romanian Academy, "Emil Racovita" Institute of Speleology, Bucarest pp. 121-124〕 The remains from France may actually belong to ''Polacanthus'' and the other references are today also considered dubious.〔〔 However, possible remains were reported from Germany in 2013: a spike, specimen DLM 537 and the lower end of a humerus, specimen GPMM A3D.3, which were referred to a ''Hylaeosaurus'' sp. 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「Hylaeosaurus」の詳細全文を読む スポンサード リンク
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