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 Diemen’s Land; since it is in the Australian seas that is found the Cestracion, a cartilaginous fish which has teeth that are most like those fossil teeth called Acrodus and Psammodus, so common in the oolite. In the same Australian seas, also, near the shore, the beautiful shell-fish called Trigonia is found living, of which genus many fossil species occur in the Stonesfield slate. Moreover, the Araucarian pines are now abundant, together with ferns, in Australia, as they were in Europe in the oolitic period.