Iguanodon

“ Although some important data are still required to complete our knowledge of the structure of the Iguanodon, we are warranted in concluding that this colossal herbivorous reptile was as bulky as the elephant, and as massive in its proportions: for, living exclusively on vegetable substances, the abdominal region must have been largely developed. Its limbs must have been of proportionate size to support and move so enormous a carcass. ”

“ Had we seen a megatherium or a mylodon or a megalonyx crossing our path, or observed a mastodon pushing his bulky form through the dense underbrush; had we seen a screaming pterodactyl passing over our heads, or beheld a giant iguanodon floundering in the morass by the wayside, or browsing on the succulent crowns of the Mauritia flexuosa, we should have regarded it all as in perfect keeping with our environment. ”

“ It was of enormous size and power, like an erect elephant, but its movements, in spite of its bulk, were exceedingly alert. For a moment, as I saw its shape, I hoped that it was an iguanodon, which I knew to be harmless, but, ignorant as I was, I soon saw that this was a very different creature. Instead of the gentle, deer-shaped head of the great three-toed leaf-eater, this beast had a broad, squat, toad-like face like that which had alarmed us in our camp. ”

“ In Iguanodon it has the obturator process characteristic of the same bone in Birds; and I imagine that the same process is seen in Compsognathus. In Hypsilophodon there can be no mistake about the matter, and the remarkable slenderness and prolongation of the ischium gives it a wonderfully ornithic character. In Iguanodon this slenderness and prolongation are carried beyond what is to be seen in Birds. I am disposed to think, however, that, as was certainly the case in Hypsilophodon, the ischia united in a median ventral symphysis in all the Dinosauria. ”

“ But the difference in size between the living and the extinct reptile is enormous. The iguana is from four to six feet long; the iguanodon was certainly thirty feet, perhaps fifty or sixty feet long, and of bulk several times greater than that of an elephant. A thigh-bone has been found fifty-six inches long, twenty-two inches in circumference at the shaft, and forty-two inches at the condyle. Its habits are supposed to have been something like those of a hippopotamus. Like this animal, it wallowed in the mud, and fed on the rank herbage of marshy grounds. ”

“ No external armour has been found. The reptile doubtless frequented marshes, feeding on the succulent vegetation, and often swimming in the 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 Wealden formation of Sussex, and a large part of the skeleton, lacking the head, was subsequently discovered in a block of ragstone in the Lower Greensand near Maidstone, Kent. ”

“ The Hylæosaurus and Iguanodon were both found in the Tilgate Forest beds, but have been noticed under the fauna of the oolite series, as probably living in the age of, as they approach so closely in structure and size to, the reptilian types of the deposit; frequenting the woods and pastures, while their mighty cotemporaries were following their instincts in the seas and lakes of the district. ”

“ These were times incredibly remote, when land animals were not in existence, when plants were represented only by seaweeds, the whole land a desert but for possibly some creeping films of vegetation adapted to life on damp soil ashore, times long ages before those strange reptiles Iguanodon, Diplodocus, the whale-like Ichthyosaurus, the giant ferns and lycopods of the coal measures, whose fossil remains remind us of nightmare worlds which have passed away, had ever come into being. ”

“ However strange it may appear to find its dimensions so much exceeding those of any existing Lizards, or to find marine genera in the order of Saurians, in which there exists at this time no species capable of living in the sea; it is scarcely less strange than the analogous deviations in the Megalosaurus and Iguanodon, which afford examples of still greater expansion of the type of the Monitor and Iguana, into colossal forms adapted to move upon the land. ”

“ Instead of the iguanodon, and the hideous reptiles that occupied the water and the land before, new races were seen. Along the rivers and marshes were now the hippopotamus, tapir, and rhinoceros; upon the land were browsing herds of deer of enormous size, and groups of elephants and mastodons, of colossal magnitude.
This era also passed away; these mighty animals became entombed in the earth; the vegetable world was changed; swine, horses and oxen were now seen upon the land, and man, the head of creation, spread over the earth, and assumed dominion over the animal tribes. ”

“ But the ancestral birds became adapted to flying, the ancestral Predentates to terrestrial life, and in their later development became as widely diversified in form and habits as the warm-blooded quadrupeds which succeeded them in the Age of Mammals.
Fig. 25.—Skulls of Iguanodont and Trachodont Dinosaurs. Iguanodon and Camptosaurus of the Jurassic and Comanchic; Kritosaurus and Corythosaurus of the Middle Cretacic (Belly River) ; Saurolophus of the late Cretacic (Edmonton) ; Trachodon of the latest Cretacic (Lance) . The Iguanodon is European, the others North American. All 1/25 natural size. ”

“ Mantell was of the opinion that the iguanodon had a nasal integumental horn. We reproduce in Fig. 3 a picture of the reptile restored, according to the ideas prevailing among geologists ten years ago, in contrast with a view of the actual skeleton set up in the museum at Brussels, as an illustration of the danger of making too hasty generalizations from too few or too imperfectly understood data. ”

“ A small creature, less than 5 feet in length. Four fingers, with 2, 3, 4, 2 phalanges; fifth metacarpal vestigial. Four toes with 2, 3, 4, 5 phalanges and long claws. Astragalus and calcaneum separate. Post-pubis very slender. Each premaxillary with five pointed alveolar teeth, leaving a wide median diastema; maxillaries with eleven, dentaries with ten laterally compressed blade-like teeth.
Iguanodon from the Wealden of England, Belgium, and Germany. Apparently two species, I. mantelli, about 16 feet, I. bernissartensis nearly 30 feet long. ”

“ In New Jersey, geologists have dug up the fossil bones of an animal they call the Iguanodon, a sort of frog with a snake tail; when he sat up his head was about thirty feet high. Had he lived on men he would have eaten three [74] for dinner. It seems that when those animals raised up on all four, like elephants, they lost their fish-like tails, except to use as fly whiskers. Those animals lived all through what is called the mammalian age in geology, or the sixth day in the Bible. ”

“ Fig. 140.—Ammonites rostratus.
(Upper Greensand.)
The Iguanodon, signifying Iguana-toothed (from the Greek word, οδους, tooth) , was more gigantic still than the Megalosaurus; one of the most colossal, indeed, of all the Saurians of the ancient world which [293] research has yet exposed to the light of day. Professor Owen and Dr. Mantell were not agreed as to the form of the tail; the former gentleman assigning it a short tail, which would affect Dr. Mantell’s estimate of its probable length of fifty or sixty feet; the largest thigh-bone yet found measures four feet eight inches in length. ”

“ In the Ichthyosauri and Plesiosauri, whose paddles were calculated exclusively to move in water, even the largest bones of the arms and legs were solid throughout. Their weight would in no way have embarrassed their action in the fluid medium they inhabited; but in the huge Megalosaurus, and still more gigantic Iguanodon, which are shown by the character of their feet to have been fitted to move on land, the larger bones of the legs were diminished in weight, by being internally hollow, marrow, while their cylindrical form tended also to combine this lightness with strength. ”

“ The Iguanodons of the Wealden epoch did not live and die where their bones are now found—the condition in which their fossil relics occur proves that they floated down the streams and rivers, with rafts of trees and other spoils of the land, till, arrested in their course, they sank down and became buried in the fluviatile and sometimes marine sediments then being slowly laid down. ”

“ Some observers believe they have found in the foot-prints evidences that a slight web existed between the toes. M. Dollo has drawn a conjectural outline of the body of the iguanodon, which is represented in our large cut. Leaving out the long tail, its general shape is that of a duck. The sectional view, represented by X in the cut, indicates that the animal was relatively very narrow and sharp-keeled, like a clipper-ship. ”

“ These three specimens are the only parts of the jaws of the Iguanodon, with the exception of a fragment of the angular bone, that I have had the opportunity of examining. The other portions of the skeleton hitherto discovered are the following: the tympanic bone; [134] cervical, dorsal, lumbar, and caudal vertebræ, and chevron bones; ribs; the iliac bones, and sacrum composed of six anchylosed vertebræ; [135] the coracoid, scapula and clavicles; humerus, radius? metacarpals; femur, tibia and fibula, metatarsals and ungueals. The cranium, carpals, and tarsals, have not been discovered. ”

“ The post-pubic branches are very slender, distally much reduced, and, except at the obturator-foramen, separated from the ischia; the pre-pubes are very strong and broad. The femur has a fourth trochanter, a feature which {428}induced the unfortunate late Paul Albrecht to declare that Iguanodon was a reptilian Duck! The tarsal bones are separate. The metatarsals and toes are reduced to three, with 3, 4, 5 phalanges respectively, the first being a mere styliform vestige. The anterior limbs are likewise very powerful, but are much shorter ”

“ What are truly characteristic of the upper molars of that herbivorous Dinosaurian are the ridges on the outer surface of the crown, which ridges, being also present in Pox's Iguanodon, and supposed to be peculiar thereto, suggested to Prof. Huxley the term Hypsilopliodon. But the lower molars of Iguanodon are equally ridged, but on the opposite side to those above, viz. the inner side; and the marginal serrations extend nearer to the base of the crown. Now the lower molars of the small Iguanodon, also found, with the mandible, by Mr. ”

“ The vertebræ of the Iguanodon are distinguishable from those of other reptiles which occur in the same strata by the following peculiarities, which the figure of a perfect specimen of a caudal vertebra (Lign. 206, fig. 3) will serve to illustrate. The body, or centrum, is either flat or somewhat depressed on both articular faces; its sides are nearly flat, or somewhat convex, vertically (as in fig 3) , and slightly concave lengthwise, or from front to back: in some examples, the body is more contracted towards the inferior surface, as in fig. ”

“ His reputation rapidly grew, especially after his discovery of the iguanodon in the sandstone of Tilgate Forest, an account of which was read before the Royal Society early in 1825, and is printed in the ‘Philosophical Transactions,’ cxv. ”

“ The fore-limbs of the animal have five and the hind-limbs four claws, or toes, leaving a three-toed track. Here, again, is another and probably the most decisive proof that the iguanodon walked on its hind-limbs only. The feet have been compared by M. Dollo with the tridactyl Wealden foot-prints—which the iguanodon only among known Wealden dinosaurians could have made—and have been found to fit accurately. "If the animal had walked on all-fours," Mr. ”

“ As to birds, the only notable instance in which discoveries recently made appear to fill up an important hiatus, is the interpretation given by Professor Huxley [127] to the remains of Dinosaurian reptiles, and which were noticed in the third chapter of this work. The learned Professor has (as also has Professor Cope in America) shown that in very important and [131] significant points the skeletons of the Iguanodon and of its allies approach very closely to that existing in the ostrich, emeu, rhea, &c. ”

“ Mantell solely belongs the 686credit of having established the existence of several families of land lizards, whose magnitude far exceeds that of the marine saurians. The bones of the iguanodon, of the hylæosaurus, and pelorosaurus, are colossal—equal to those of the largest elephants, and in some individuals even surpassing them, while their length, in some instances, was equal to that of the longest whales. The form of their teeth, and the hollow condition of their bones, with a large canal for marrow, prove that their habits were those of terrestrial animals ”

“ The probable size of the Iguanodon was thirty feet in length, though probably some exceeded these enormous proportions. Seventy species have been discovered in the quarries 189opened at Tilgate forest; and this gives us some idea of the conspicuous part these mighty creatures once played in the eras happily before man was an inhabitant of this planet. Why these remains should generally be found in the same locality we cannot certainly tell, though the previous extract from Alison may shed some light on this curious fact ”

“ Since we had learned that the huge iguanodons were kept as tame herds by their owners, and were simply walking meat-stores, we had conceived that man, even with his primitive weapons, had established his ascendancy upon the plateau. We were soon to discover that it was not so, and that he was still there upon tolerance. It was on the third day after our forming our camp near the Indian caves that the tragedy occurred. ”