Extinct Monsters / A Popular Account of Some of the Larger Forms of Ancient Animal Life

by H. N. Hutchinson

It is all the more important to give to the general reader this warning, because an impression seems still to remain in the popular mind that Owen could and did restore extinct types from a single bone or a single tooth; but no anatomist would attribute to any mortal man such superhuman power. Let us, therefore, while gratefully acknowledging the debt we all owe to the great naturalist—who has gone to his rest since our first edition appeared—not attribute to him impossible things. Nor can it be denied that even he sometimes fell into error, or drew conclusions not borne out by later discoveries. It must also be confessed that in some respects he lagged behind in the march of scientific progress. While on this subject we cannot do better than quote some remarks of our friend, Mr. A. Smith Woodward, of the Natural History Museum, in an able review of Sir Richard’s work on vertebrates.[15] He says, "Owen, in fact, was Cuvier’s direct successor, and, apart from his striking hypotheses ..., it is in this character that he has left the deepest impression upon biological science. Extending and elaborating comparative anatomy as understood by Cuvier, Owen concentrated his efforts on utilising the results for the interpretation of the fossil remains—even isolated bones and teeth—of extinct animals. He never hesitated to deal with the most fragmentary evidence, having complete faith in the principles established by Cuvier; and it is particularly interesting, in the light of present knowledge, to study the long series of successes and failures that characterise his work. However, unwittingly, Owen may be said to have contributed most to the demolition of the narrow Cuvierian views. When dealing with animals closely related to those now living, his correctness of interpretation was usually assured; when treating of more remote types, he could do little more than guess, unless tolerably complete skeletons happened to be at his disposal....

“In short, Owen’s work on fragmentary fossils has demonstrated that the principles of comparative anatomy are very different from those inferred by Cuvier from his limited field of observation, and the discoveries of Leidy, Marsh, Cope, Scott, and Osborn, in America, have finally led to a new era that Owen only began to foresee clearly in his later days.”

[15] Natural Science, ii. p. 130. (Feb. 1893.)

The first specimens of teeth of the Iguanodon were found by Mrs. Mantell, in 1822, in the coarse conglomerate of certain strata in Tilgate Forest, belonging to the Cretaceous period (see [Table of Strata, Appendix I.]). Dr. and Mrs. Mantell subsequently collected a most interesting series of these remarkable teeth (which, for a time, puzzled the most learned men of the day), from the perfect tooth of a young animal, to the last stage, that of a mere long stump worn away by mastication. In external form they bore a striking resemblance to the grinders of herbivorous mammals, and were wholly unlike any that had previously been known. Even the quarrymen, accustomed to collect the remains of fishes, shells, and other objects embedded in the rocks, had not observed fossils of this kind; and until Dr. Mantell showed them his specimens, were not aware of the presence of such teeth in the stone they were constantly breaking up for the roads. The first specimen that arrested his attention was a large tooth, which, from the worn surface of its crown, had evidently once belonged to some herbivorous animal. In form it so entirely resembled the corresponding part of an incisor tooth of a large pachydermatous animal ground down by use, that Dr. Mantell was much embarrassed to account for its presence in the ancient Wealden strata, in which, according to all previous experience, no fossil remains of mammals would be likely to occur. No reptiles of the present day are capable of masticating their food; how, then, could he venture to assign it to a reptile? Here was a puzzle to be solved, and in his perplexity he determined to try whether the great naturalist at Paris would be able to throw any light on the question. Through Sir Charles (then Mr.) Lyell, this perplexing tooth was submitted to Baron Cuvier; and great was the doctor’s astonishment on hearing that it had been without hesitation pronounced to be the upper incisor of a rhinoceros! The same tooth, with some other specimens, had already been exhibited at a meeting of the Geological Society, and shown to Dr. Buckland, Mr. Conybeare, and others, but with no more satisfactory result. Worse than that: Dr. Mantell was told that the teeth were of no particular interest, and that, without doubt, they either belonged to some large fish, or were the teeth of a mammal, and derived from some superficial deposit of the “glacial drift,” then called Diluvium.

There was one man, however, who foresaw the importance of Mantell’s discovery, and that was Dr. Wollaston. This distinguished philosopher, though not a naturalist, supported the doctor’s idea that the teeth belonged to an unknown herbivorous reptile, and encouraged him to continue his researches.

As if to add to the difficulty of solving the enigma, certain bones of the fore limb, discovered soon after in the same quarry and forwarded to Paris, were declared to belong to a species of hippopotamus! Another very curious bone—of which we shall speak presently—was declared to be the lesser horn of a rhinoceros! The famous Dr. Buckland even went so far as to warn Dr. Mantell not to publish it forth that these bones and teeth had been found in the Tilgate Forest strata. To him it seemed incredible that such remains could have been obtained from beds older than the superficial drift deposits of the district. We must bear in mind that in those days palæontology, or the knowledge of the world’s former inhabitants, was a new science still in its infancy, and the idea of mammals having existed so far back as the Cretaceous period must have appeared incredible.

However, the workmen in the quarry were stimulated by suitable rewards, and at length the doctor’s efforts resulted in the discovery of teeth which displayed the curious serrated edges, and the entire form of the unused crown. Having forwarded specimens and drawings of these to Paris, Dr. Mantell went to London, and ransacked all the drawers in the Hunterian Museum that contained jaws and teeth of reptiles, but without finding any that threw light on this subject. Fortunately, Mr. Samuel Stuchbury, then a young man, was present, and proposed to show him the skeleton of an Iguana, which he had himself prepared from a specimen that had long been immersed in spirits. And now the puzzle was in a fair way to being solved; for, to his great delight, the doctor found that the minute teeth of that reptile bore a closer resemblance in their general form to those from Tilgate Forest than any others he had ever seen.

In spite of this fortunate discovery, however, others remained obstinate and unconvinced; and it was not until he had collected a series of specimens, exhibiting various stages of the teeth, that the correctness of his opinion was admitted, either as to their true interpretation, or the age of the strata in which they were imbedded. And now there came good news from Paris. Cuvier, with the fresh material submitted to him, had boldly renounced his previous opinion, and gave the weight of his great authority to the view maintained by the discoverer of these teeth. In a letter to the doctor he said that such teeth were quite unknown to him, and that they belonged to some reptile. He suggested that they implied the existence of a new animal, a herbivorous reptile. Time would either confirm or disprove the idea, and in the mean time he advised Dr. Mantell to seek diligently for further evidence, and, if part of a jaw could be found with teeth adhering, he believed he could solve the problem. In his immortal work, Ossemens Fossiles, Cuvier generously admits his former mistake, and said he was entirely convinced of his error.

Baron Cuvier alone amongst the doctor’s friends or correspondents was able to give any hint as to the character and probable relations of the animal to which the recently discovered teeth belonged. Being hampered by arduous professional duties in a provincial town, remote from museums and libraries, Dr. Mantell transmitted to the Royal Society figures and drawings of the specimens, and, at the suggestion of the Rev. W. D. Conybeare, adopted the name Iguanodon (Iguana-tooth) for the extinct reptile, a name which pointed to the resemblance of its teeth to those of the modern iguana, a land-lizard inhabiting many parts of America and the West Indies, and rarely met with north or south of the tropics. These lizards are from three to five feet in length, and perfectly harmless, feeding on insects and vegetables, and climbing trees in quest of the tender leaves and buds, which they chip off and swallow whole; they nestle in the hollows of rocks, and deposit their eggs in the sands and banks of rivers.

In all living reptiles the insects or vegetables on which they feed are seized by the tongue or teeth, and swallowed whole, so that a movable covering to the jaws, similar to the lips and cheeks of the mammalia, is not necessary, either for seizing and retaining food, or for subjecting it by muscular movements to the action of the teeth. It is the power of perfect mastication possessed by the Iguanodon that is so strange, for it implies a most remarkable approach in extinct reptiles to characters possessed now only by herbivorous mammalia, such as horses, cows, deer, etc. From this and other strange characters seen in the Dinosaurs, we learn that they in their day played the part of our modern quadrupeds, whether carnivorous or herbivorous, and showed a remarkable approach to the mammalian type, which of course is a much higher one.