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IGUANODON

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Originally appearing in Volume V14, Page 297 of the 1911 Encyclopedia Britannica.
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IGUANODON , a large See also:

extinct herbivorous See also:land reptile from the See also:Wealden formation of western See also:Europe, almost completely known by numerous skeletons from Bernissart, near See also:Mons, See also:Belgium. It is a typical representative of the ornithopodous (Gr. for See also:bird-footed) Dinosauria. The See also:head is large and laterally compressed with a See also:blunt snout, nearly terminal nostrils and relatively small eyes. The sides of the jaws are provided with a See also:close See also:series of grinding See also:teeth, which are often worn down to stumps; the front of the jaws forms a toothless See also:beak, which would be encased originally in a horny sheath. When unworn the teeth are spatulate and crimped or serrated See also:round the edge, closely resembling those of the existing Central See also:American See also:lizard, See also:Iguana--hence the name Iguanodon (Gr. Iguana-tooth) proposed by See also:Mantell, the discoverer of this reptile, in 182s. The bodies of the vertebrae are solid; and they are convexoconcave (i.e. opisthocoelous) in the See also:neck and anterior See also:part of the back, where thrre must have been much freedom of See also:motion. The hindquarters are comparatively large and heavy, while the tail is See also:long, deep and more or less laterally compressed, evidently adapted for See also:swimming. The small and See also:mobile fore-limbs See also:bear four See also:complete fingers, with the thumb reduced to a bony See also:spur. The See also:pelvis and See also:hind-limbs much resemble those of a See also:running bird, such as those of an emu or the extinct See also:moa; but the basal bones (metatarsals) of the three-toed See also:foot remain See also:separate throughout See also:life, thus differing from those of the running birds, which are firmly fused together even in the See also:young adult. No See also:external See also:armour has been found. The reptile doubtless frequented marshes, feeding on the succu- See also:lent vegetation, and often swimming in the See also:water.

Footprints prove that when on land it walked habitually on its hind-limbs. The earliest remains of Iguanodon were found by Dr G. A. Mantell in the Weal-den formation of See also:

Sussex, and a large part of the See also:skeleton, lacking the head, was subsequently discovered in a See also:block of ragstone in the See also:Lower See also:Greensand near after it and it then stopped as a timid See also:dog would do, crouching down and permitting me to seize it by the neck and carry it off." Along with several other See also:species, notably Ctenosura acanthinura, which is omnivorous, likewise called iguana, the See also:common iguana, is much sought after in tropical See also:America; the natives esteem its flesh a delicacy, and See also:capture it by slipping a noose round its neck as it sits in fancied See also:security on the See also:branch of a See also:tree. Although chiefly arboreal, many of the iguanas take readily to the water; and there is at least one species, Amblyrhynchus cristatus, which leads for the most part an aquatic life. These marine lizards occur only in the Galapagos Islands, where they are never seen more than 20 yds. inland, while they may often be observed in companies several hundreds of yards from the See also:shore, swimming with See also:great facility by means of their flattened tails. Their feet are all more or less webbed, but in swimming they are said to keep these See also:organs motionless by their sides. ~ See also:Maidstone, See also:Kent. These fossils, which are now in the See also:British Their See also:food consists of marine vegetation, to obtain which they dive beneath the water, where they are able to remain, without coining to the See also:surface to breathe, for a very considerable See also:time. Though they are thus the most aquatic of lizards, See also:Darwin, who studied their habits during his visit to those islands, states that when frightened they will not enter the water. Driven along a narrow ledge of See also:rock to the edge of the See also:sea, they preferred capture to See also:escape by swimming, while if thrown into the water they immediately returned to the point from which they started. A land 'species belonging to the allied genus Conolophus also occurs in the Galapagos, which differs from most of its See also:kind in forming burrows in the ground.

Skeleton of Iguanodon bernissartensis. (After Dollo.) Museum, were interpreted by Dr Mantell, who made comparisons with the skeleton of Iguana, on the erroneous supposition that the resemblance in the teeth denoted some relationship to this existing lizard. Several of the bones, however, could not be understood until the much later discoveries of Mr S. H. Beckles in the Wealden cliffs near See also:

Hastings; and an accurate knowledge of the skeleton was only obtained when many complete specimens were disinterred by the Belgian See also:government from the Wealden beds at Bernissart, near Mons, during the years 1877-1880. These skeletons, which now See also:form the most striking feature of the See also:Brussels Museum, evidently represent a large See also:troop of i animals which were suddenly destroyed and buried in a deep See also:ravine or See also:gully. The typical species, Iguanodon mantelli, See also:measures 5 to 6 metres in length, while I. bernissartensis (see fig.) attains a length of 8 to lo metres. They are found both at Bernissart and in the See also:south of See also:England, while other species are also known from Sussex. Nearly complete skeletons of allied See also:reptiles have been discovered in the See also:Jurassic and Cretaceous rocks of See also:North America.

End of Article: IGUANODON

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