A Pictorial Atlas of Fossil Remains, consisting of coloured illustrations selected from Parkinson's "Organic remains of a former world," and Artis's "Antediluvian phytology."

by Gideon Algernon Mantell

During the incalculable ages which the formation of the various systems of secondary strata must have comprised, we find no evidence in the fossils hitherto observed, of the existence of birds and mammalia, as the characteristic types of the faunas of the dry land. On the contrary, throughout the immense accumulations of the spoils of the ancient islands and continents, amidst innumerable relics of reptiles of various orders and genera, a few jaws and bones of two or three kinds of extremely small marsupials, and the bones of a species of wader, are the sole indications of the presence of the two grand classes of Aves and Mammalia, which now constitute the chief features of the terrestrial zoology of almost all countries.

The earliest indications of air-breathing vertebrata in the ancient secondary formations are those of small saurian reptiles in the carboniferous strata; a few vestiges occur in the succeeding group, the Permian. In the next epoch, the Triassic, colossal Batrachians (Labyrinthodonts) appear; and on some of the strata of this formation are the footmarks of numerous bipeds, presumed to be those of birds; but at present the evidence of the bones of the animals that made those imprints is required to establish the hypothesis.

In the succeeding eras, the Lias, Oolite, Wealden, and Cretaceous, swarms of reptiles of numerous genera and species everywhere prevail; reptiles fitted to fly through the air, to roam over the land, to inhabit the lakes, rivers, and seas; and yet not one identical with any existing forms! These beings gradually decline in numbers and species as we approach the close of the secondary periods, and are immediately succeeded in the eocene epoch, by as great a preponderance of warm-blooded vertebrata—birds and mammalia—as exists at the present time; and an equal decadence in the class of reptiles. With the Cretaceous Formation the "Age of Reptiles" may be said to terminate.

[XVII.]—Fossil Reptiles of the Wealden. The Iguanodon. The fluviatile deposits (termed Wealden), which in the south-east of England, and in the north of Germany, are intercalated between the oolitic and cretaceous formations, abound in the bones of terrestrial, fresh-water, and marine reptiles, comprising some of the most colossal land-saurians which have hitherto been brought to light. These remains belong to various genera of Chelonians, Saurians, and Crocodilians; and with these are associated those of flying lizards (Pterodactyles), Plesiosauri, gigantic whale-like reptiles (Cetiosauri), and of other oviparous quadrupeds of unknown species and genera.

The occurrence of fossils of this nature in the strata forming the districts denominated the Wealds of Sussex and Kent, was first brought under the notice of geologists in 1822, in my work on the "Fossils of the South Downs," in which the remains of several unknown reptiles were described; and among them the teeth and bones of that extraordinary herbivorous lizard, the Iguanodon, on which I am induced to offer a few observations in this place; the recent discovery of some previously undetermined parts of the skeleton, having materially elucidated the structure and economy of the original.[132]

[132] The following is the description of the specimens first discovered, given in the "Fossils of the South Downs; or, Illustrations of the Geology of Sussex," 1 vol. 4to. 1822: "Incisors and molar teeth evidently belonging to the same species of animal: they differ from any previously known; the masticating surface is perfectly smooth and rather depressed in the centre; these teeth consist of the crown only, and are quite solid. An incisor tooth 1.3 inch long Is slightly bowed and smooth on its inner surface; but it has externally a ridge which extends longitudinally down the front. Its sides are angular and the edges finely crenated." From the resemblance of these teeth in their general form to those of the Iguana, a common land lizard in the West Indies, I subsequently proposed the name of Iguanodon (implying an animal having teeth like the Iguana) for the fossil reptile. The teeth of an Iguana four or five feet long are not larger than those of a mouse; the Iguanodon's teeth are as large as the incisors of the rhinoceros. The Iguana's teeth, when used, are chipped off at the points, no existing reptile being capable of performing mastication; the teeth of the Iguanodon, on the contrary, are ground down like the worn molars of herbivorous mammalia, as I pointed out in my first memoir in the Philos. Trans. 1825.

Since the first announcement of the discovery of the remains of the Iguanodon, vast quantities of bones belonging to a great number of individuals of all ages have been collected; but until a few years since, not a vestige of the jaws had been observed, notwithstanding the most diligent research. In the early part of the year 1848, I was surprised and highly gratified by receiving from Capt. Lambart Brickenden (at that time a personal stranger to me), who then resided at Warminglid, near Cuckfield, in Sussex, the greater part of the right side (or ramus) of the lower jaw, with several successional teeth in their natural position, of an adult Iguanodon.[133] See p. 202.

[133] This beautiful and most instructive specimen is now in my possession; it is figured of the natural size in Philos. Trans. Part ii. for 1848, Plate XVI., as well as the portion of upper jaw in the British Museum, Plate XIX. The character of the upper and lower teeth of the Iguanodon are well represented in Plate XVIII. of the same memoir.

A specimen very similar to that discovered by Capt. Brickenden, but of a young individual, was found soon afterwards in a quarry near Horsham; but I was not allowed the privilege of figuring or describing it!