AN ARMOURED DINOSAUR, SCELIDOSAURUS HARRISONI.
Length 12 feet or more.
Fig. 24.—Restored skeleton of Scelidosaurus Harrisoni (after Woodward), greatly reduced, from the Lower Lias of Charmouth, Dorset. The figure shows the large lateral dermal spines on the shoulders, and the long lateral line of smaller spines, reaching from the pectoral region to the extremity of the tail.
The next monster to be described is one that has fortunately left to posterity a much better record of itself, and probably was not very unlike the Hylæosaurus of Mantell. This is the Scelidosaurus: so named by Professor Owen from the indications of greater power in the hind legs than in most saurians.[20] It is the only known example of an almost entire skeleton of an English Dinosaur, and the history of its discovery is rather curious. Some time previous to 1861, Mr. J. Harrison, of Charmouth, obtained from the Lower Lias of that neighbourhood portions of the hind limb of a Dinosaur, and, later on, a nearly complete skull. These specimens were described by Owen, and the genus was founded on them. Mr. Harrison, whose discovery aroused great interest, continued to search on the same spot, and was rewarded by finding all the rest of the skeleton, except most of the neck vertebræ. This was extracted in several blocks, and these, after careful “development” of the bones, were fitted together so as to exhibit the whole skeleton. This most valuable specimen can now be seen at South Kensington in a separate glass case, and is one of the treasures of the unrivalled gallery of fossil reptiles. The case is placed so that both sides of the specimen can be seen (Case Y, Gallery IV., on plan). Its length is about twelve feet; perhaps the individual it represents was not fully grown, but, on account of the absence of most of the neck vertebræ, it is impossible to give the exact length. Both hind limbs are entire and well seen, but of the fore limbs the hands are wanting. The former were provided with four “functional” toes—that is, toes that were used,—and one “rudimentary” or unused one. There were two big spines, one placed on each shoulder, and a series of long plates arranged in lines along the back and side. Plate IX. shows an attempted restoration of this remarkable Dinosaur based upon the skeleton just described. It seems to have been organised for a terrestrial rather than an aquatic life, but to have been amphibious, frequenting the margins of rivers or lakes. Professor Owen considers that the carcase of this individual drifted down a river emptying itself in the old Liassic Sea, on the muddy bottom of which it would settle down when the skin had been so far decomposed as to permit the escape of gases due to decomposition. In that case the carcase would attract large carnivorous fishes and reptiles, such as swarmed in this old sea, so that portions of the skin and flesh would probably be torn away before the weight of the bones had completely buried it in mud. In this way, perhaps, the loss of much of the external armature and of the two fore feet may be accounted for. The hind limbs, being stronger, were better able to resist such attacks, and they are therefore preserved. Like many other specimens, this fossil has, in the course of ages, been subjected to enormous pressure from overlying strata, causing compression and dislocation or fracture.
[20] From Greek—scelis, limb, and sauros, lizard.
But there were in existence during the long Jurassic period, other and even stranger forms of armoured Dinosaurs. One of these, only imperfectly known at present, was the many-spined Polacanthus.[21] This remarkable monster had the whole region of the loins and haunches protected by a continuous sheet of bony plate armour, rising into knobs and spines, after the fashion of the shield or carapace of certain extinct armadillos known as Glyptodonts (See [Chapter XII.]). A specimen of such a shield is to be seen in the collection at South Kensington (Wall-case 4). It is to be hoped that, some day, further remains of the Polacanthus will be brought to light, so that a restoration may become possible. Dr. Mantell had already pointed out certain analogies between Iguanodon and the huge extinct sloths of the South American continent, that flourished in the much more recent Pleistocene period; and this idea is now considerably strengthened by the later discoveries of armoured Dinosaurs. These are his words: “In fine, we have in the Iguanodon the type of the terrestrial herbivora which, in the remote epoch of the earth’s physical history termed by geologists the age of Reptiles, occupied the same relative position in the scale of being, and fulfilled the same general purposes in the economy of nature, as the Mastodons, Mammoths, and Mylodons (extinct sloths) of the Tertiary period, and the existing pachyderms.”
[21] From Greek—polus, many, and acantha, spine.