  The division of the secondary formations, called “Oolite,” takes its name from the most characteristic of its constituents, which is a variety of limestone composed of numerous small grains, resembling the “roe” or eggs of a fish, whence the term, (from the Greek oon, an egg, lithos, a stone). The oolite, however, includes a great series of beds of marine origin, which, with an average breadth of thirty miles, extend across England, from Yorkshire in the north-east to Dorsetshire in the south-west. The oolite series lies below the Wealden, and where this is wanting, below the chalk, and consists of the following subdivisions, succeeding each other in the descending order:—
Upon the portion of the island representing the oolite series, the most conspicuous of the restored animals of that period is— No. 7.—The Megalosaurus.The Megalosaurus, as its name implies (compounded by its discoverer, Dr. Buckland, from the Greek megas, great, and sauros, lizard), was a lizard-like reptile of great size, “of which,” writes Dr. Buckland, “although no skeleton has yet been found entire, so many perfect bones and teeth have been discovered in the same quarries, that we are nearly as well acquainted with the form and dimensions of the limbs as if they had been found together in a single block of stone.” The restoration of the animal has been accordingly effected, agreeably with the proportions of the known parts of the skeleton, and in harmony with the general characters of the order of reptiles to which the Megalosaurus belonged. This order—the Dinosauria (Gr. deinos, terribly great sauros, a lizard)—is that to which the two foregoing huge reptiles of the Wealden series belong, viz., the Iguanodon and HylÆosaurus, and is characterised by the modifications already mentioned, that fitted them for more efficient progression upon dry land. The Iguanodon represented the herbivorous section of the order, the HylÆosaurus appears, from its teeth, to have been a mixed feeder, but the Megalosaurus was decidedly carnivorous, and, probably, waged a deadly war against its less destructively endowed congeners and contemporaries. No. 7. Megalosaurus. Baron Cuvier estimated the Megalosaurus to have been about fifty feet in length; my own calculations, founded on more complete evidence than had been at the Baron’s command, reduce its size to about thirty-five feet: As the thigh-bone (femur) and leg-bone (tibia) measure each nearly three feet, the entire hind-leg, allowing for the cartilages of the joints, must have attained a length of two yards: a bone of the A minute and interesting description of these teeth will be found in Dr. Buckland’s admirable “Bridgewater Treatise” (vol. i. p. 238), from which he concludes that the teeth of the Megalosaurus present “a combination of contrivances analogous to those which human ingenuity has adopted in the construction of the knife, the sabre, and the saw.” The fossils which brought to light the former existence of this most formidable reptile, were discovered in 1823, in the oolitic slate of Stonesfield, near Oxford, and were described by Dr. Buckland, in the volume of the “Geological Transactions” for the year 1824. Remains of the Megalosaurus have since been discovered in the “Bath oolite,” which is immediately below the Stonesfield slate, and in the “Cornbrash,” which lies above it. VertebrÆ, teeth, and some bones of the extremities have been discovered in the Wealden of Tilgate Forest, Kent, and in the ferruginous sand, of the same age, near Cuckfield, in Sussex. Remains of the Megalosaurus also occur in the Purbeck limestone at Swanage Bay, and in the oolite in the neighbourhood of Malton, in Yorkshire. Mr. Waterhouse Hawkins’s restoration, according to the proportions calculated from the largest portions of fossil bones of the Megalosaurus hitherto obtained, yields a total length of the animal, from the muzzle to the end of the tail, of thirty-seven feet; the length of the head being five feet, the length of the tail fifteen feet; and the greatest girth of the body twenty-two feet six inches. Nos. 8 & 9.—Pterodactyles of the Oolite.To the right of the HylÆosaurus, on the rock representing the greater oolite formation, are restorations of species of Pterodactyle (Pterodactylus Bucklandi, No. 9), smaller than and distinct from those of the chalk formations. The remains of Buckland’s Pterodactyle are found pretty abundantly in the oolitic slate of Stonesfield, near Oxford. Nos. 10 & 11.—Teleosaurus.On the shore beneath the overhanging cliff of oolitic rock are two restorations, Nos. 10 and 11, of a large extinct kind of crocodile, to which the long and slender-jawed crocodile of the Ganges, called “GaviÀl” or “GharriÀl” by the Hindoos, offers the nearest resemblance at the present day. Remains of the ancient extinct British gavials have been found in most of the localities where the oolitic formations occur, and very abundantly in the lias cliffs near Whitby, in Yorkshire. The name Teleosaurus (telos, the end, sauros, a lizard), was compounded from the Greek by Professor Geoffroy St. Hilaire, for a species of these fossil gavials, found by him in the oolite stone at Caen, in Normandy, and has reference to his belief that they formed one—the earliest—extreme of the crocodilian series, as this series has been successively developed in the course of time on our planet. The jaws are armed with numerous long, slender, sharp-pointed, slightly curved teeth, indicating that they preyed on fishes, and the young or weaker individuals of co-existing reptiles. The nostril is situated more at the end of the upper jaw than in the modern gavial: the fore-limbs are shorter, and the hind ones longer and stronger than in the gavial, which indicates that the Teleosaur was a better swimmer; the vertebrÆ or bones of the back are united by slightly concave surfaces, not interlocked by cup and ball joints as in the modern crocodiles, whence it would seem that the Teleosaur lived more habitually in the water, and less seldom moved on dry land; and, as its fossil remains have been hitherto found only in the sedimentary deposits from the sea, it may be inferred that it was more strictly marine than the crocodile of the Ganges. The first specimen of a Teleosaur that was brought to light was from the “alum-schale” which forms one layer of the lofty lias cliffs of the Yorkshire coast, near Whitby. A brief description, and figures, of this incomplete fossil skeleton were published by Messrs. Wooller and Chapman, in separate communications, in the 50th volume of the “Philosophical Transactions,” in 1758. Captain Chapman observes, “it seems to have been an alligator;” and Mr. Wooller thought “it resembled in every respect the Gangetic gavial.” Thus, nearly a century ago, the true nature of the fossil was almost rightly understood, and various were the theories then broached to account for the occurrence of a supposed Gangetic reptile in a petrified state in the cliffs of Yorkshire. It has required the subsequent progress of comparative anatomy to determine, as by the characters above defined, the essential distinction of the Teleosaur from all known existing forms of crocodilian reptiles. Very abundant remains, and several species, of the extinct genus have been subsequently discovered: but always in the oolitic and liassic formations of the secondary series of rocks. The oolitic group of rocks are very rich in remains of both plants and animals: many reptiles of genera and species distinct from those here restored have been recognised and determined by portions of the skeleton. Extremely numerous are the remains of fishes, chiefly of an almost extinct order (Ganoidei), characterised by hard, shining, enamelled scales. But the most remarkable fossils are those which indisputably prove the existence, during the period of the “Great” or “Lower Oolite,” of insectivorous and marsupial mammalia—i.e., of warm-blood quadrupeds, which, like the shrew or hedgehog, fed on insects, and, like the opossum, had a pouch for the transport of the young. The lower jaw of one of these earliest known examples of the mammalian class, found in the Stonesfield slate, near Oxford, may be seen at the British Museum, to which it was presented by J. W. Broderip, Esq., F.R.S., by whom it was described in the “Zoological Journal,” vol. iii., p. 408. It is interesting to observe that the marsupial genera, to which the above fossil quadruped, called Phascolotherium, was most nearly allied, are now confined to New South Wales and Van | ||||||||||||||||||
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