It is, therefore, not to be wondered at that Dr. Mantell’s contemporaries, with the exception of Cuvier, found in the teeth we have described an awkward puzzle, and refused to believe that they belonged to a reptile. Such a notion was at variance with all previous experience, and we naturally form our conclusions to a large extent by experience. Let us, then, beware lest we allow our ideas to be limited by what after all is, as it were, only an expression of our ignorance. The Hottentot who has never seen snow would refuse to believe that rain can assume a solid form; and, in the same way, if we bind ourselves down by experience, we might refuse to believe in some of the still more wonderful dinosaurian types to be described in this chapter, such as the Triceratops, with a pair of large horns, a skull over six feet long, and limbs larger than those of the rhinoceros! (see [p. 117]).
The strange vagaries of Dinosaurs have led Professor Marsh and other authorities to exalt them, from their former position of a mere order in the reptile class, to the dignity of a sub-class all to themselves; and there is much to be said for this view. Compared with the Marsupials, living and extinct, they show an equal diversity of structure and variations in size from by far the largest land animals known down to some of the smallest.[16]
[16] Bauer, after a full critical examination of the Dinosauria, considers that one order is insufficient, and has proposed to make three orders of them, which he names after the Iguanodon, Cetiosaurus, and Megalosaurus.
The importance of discovering, if possible, a portion of the jaw of an Iguanodon was fully recognised by Dr. Mantell, and, urged on by the encouragement he had received from the illustrious Cuvier, he eagerly sought for the required evidence. But nearly a quarter of a century elapsed before it was forthcoming. In 1841 and 1848, however, portions of the lower jaw, with some teeth attached, were found; and his memoir On the Structure of the Jaws and Teeth of the Iguanodon was published by the Royal Society in 1848. For this important communication the gold medal of the society was awarded to the author. The second of these finds (by Captain Brickenden) confirmed in every essential particular the inferences suggested by the detached teeth.
The first important connected series of bones of this monster was discovered in 1834, by Mr. Bensted, in the “Kentish Rag” quarries of the Lower Greensand formation at Maidstone. Mr. Bensted, who was the proprietor of the quarry, one day had his attention drawn by the workmen to what they supposed to be petrified wood in some pieces of stone which they had been blasting. He perceived that what they supposed to be wood was fossil bone, and, with a zeal and care which have always characterised this estimable man (says Professor Owen) in his endeavour to secure for science any evidence of fossil remains in his quarry, he immediately resorted to the spot. He found that the bore, or blast, by which these remains were brought to light had been inserted into the centre of the specimen, so that the mass of stone containing it had been shattered into many pieces, some of which were blown into the adjoining fields! All these pieces he had carefully collected, and, proceeding with equal ardour and success to the removal of the matrix from the fossils, he succeeded, after a month’s labour, in exposing them to view, and in fitting the fragments in their proper place. This valuable specimen was presented to Dr. Mantell (and afterwards purchased with the rest of his collection by the British Museum), and its present condition is the result of his skill, as well as that of its discoverer. Certain gentlemen in Brighton, anxious that the specimen should be placed in the hands of the original discoverer of Iguanodon, purchased and presented it to Dr. Mantell—a tribute of respect which was highly gratifying to him. (Wall-case 6.)
It belonged to a young Iguanodon. This fortunate discovery was one of those Cuvier foresaw, and has served to verify his sagacious conjecture that some of the great bones collected by the doctor from the Wealden strata of Sussex belonged to the same animal, and to confirm other conclusions formed by the discoverer of the Iguanodon. Great was Dr. Mantell’s delight on finding that every bone he had ascribed to Iguanodon solely from analogy was present in the Maidstone specimen. One of the chief advantages of this discovery was that it afforded demonstration of the characters of the vertebræ, which, as previously stated, are very important to the anatomist. Of these Professor Owen has given full descriptions, and has shown that they differ from those of any animal previously known, whether living or extinct.
It is very interesting, in the light of recent discoveries, to read the conclusions arrived at by Mantell and Owen, with regard to the organisation of this great Wealden reptile, and to see how, with the exception of certain details, they have been confirmed. Considering the imperfect nature of the materials at their command, it is wonderful that their forecasts should have turned out so successful. Thus Professor Owen predicted for the Iguanodon a total length of twenty-eight feet, and specimens discovered of late years show a length of twenty-four feet. In some, the thigh-bone exceeded a yard in length; this indicated an animal of great size, since in the largest crocodiles this bone is scarcely a foot long. Again, Dr. Mantell, from a study of the imperfect jaw-bones in his collection, concluded that the lower jaw was invested with a well-developed fleshy flexible lip, and that the mouth was provided with a tongue of great mobility and power. “There are strong reasons,” he says, "for supposing that the lip was flexible, and, in conjunction with the long fleshy prehensile tongue, constituted the instrument for seizing and cropping the leaves and branches, which, from the construction of the molars, we may infer, constituted the chief food of the Iguanodon. The mechanism of the maxillary organs (jaws), as elucidated by recent discoveries, is thus in perfect harmony with the remarkable characters which rendered the first known teeth so enigmatical; and in the Wealden herbivorous reptile we have a solution of the problem, how the integrity of the type of organisation peculiar to the class of cold-blooded vertebrata was maintained, and yet adapted, by simple modifications, to fulfil the conditions required by the economy of a gigantic terrestrial reptile, destined to obtain support exclusively from vegetable substances; in like manner, as the extinct colossal herbivorous Edentata (sloths, See [Chapter XII.]), which flourished in South America ages after the country of the Iguanodon and its inhabitants had been swept away from the face of the earth."
Dr. Mantell also was the first to prove, from the nature of the Wealden strata, that they were deposited in or near the estuary of a mighty river. With regard to the aspect of the country in which the Iguanodon flourished, he showed that coniferous trees probably clothed its Alpine regions; palms and arborescent ferns, and cycadaceous plants (i.e. plants resembling the modern zamia, or “false palm”), constituted the groves and forests of its plains and valleys; and in its fens and marshes the equisetaceæ (mare’s-tails) and plants of a like nature prevailed.
