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:—
| Oolite. | |
|---|---|
| Upper. | Portland stone and sand. |
| Kimmeridge clay. | |
| Middle. | Coral rag. |
| Oxford clay. | |
| Lower. | Cornbrash and forest marble. |
| Great oolite and Stonesfield slate. | |
| Fuller’s earth. | |
| Inferior oolite. | |
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:[3] but with the superior proportional height and capacity of trunk, as contrasted with the largest existing crocodiles, even that length gives a most formidable character to this extinct predatory reptile.