28. With the transition period the colossal vegetation and animals which characterized this period disappeared. Perhaps it was caused by a change in atmospheric conditions, or on account of inundations having destroyed all which had life on Earth. It is probable that the two causes have contributed to this change; for, by a study of the rocks which mark the end of this period, we find signs of great earthquakes, upheavings, and eruptions which have thrown upon the Earth great quantities of lava, and also notable changes which have appeared in the three kingdoms.
29. The secondary period is characterized, under the mineral kingdom, by numerous and important beds, which attest a slow formation in the waters, and mark very different characteristic epochs.
Vegetation is less rapid and less colossal in growth than in the preceding period, caused no doubt by the diminution in heat, and humidity, and by modifications experienced by the constitutive elements of the atmosphere. To herbaceous and pulpy plants were joined those with woody stalks and, properly speaking, also the first trees.
30. Animals are still aquatic or amphibious at this time; animal life upon the Earth seeming to have made but little progress. A great quantity of shell-covered animals have been developed in the seas by the formation of calcareous substances; also new fishes of a more perfect organization than those of the previous period have appeared, also the first of the whale tribe. The most characteristic animals of this period are monstrous reptiles, among which are found:
The ichthyosaurus, a species of lizard-fish, which attained ten yards in length, the jaws of which, being of a prodigious length, were armed with one hundred and eighty teeth. Its general form was a little like the crocodile, but without the scaly breastplate; its eyes were as large as the head of man; it had fins like the whales, and spouted water into the air like them.
The plesiosaurus was another marine animal, as large as the ichthyosaurus, the excessively long neck of which was bent like that of the swan, which gave to it the appearance of an enormous serpent attached to the body of a turtle or tortoise. It had the head of a lizard and the teeth of a crocodile. Its skin must have been smooth; for no trace of scales, or carapaces, have been found. *
* In 1823 the first fossil of this animal was found in England. Later on, this same type of fossil was also found in France and in Germany.
The teleosaurus approaches nearer the actual crocodiles, which appear to be the diminutive descendants of it. Like them it had a scaly breastplate, and lived at times upon the Earth as well as in the water. Its body was about ten yards in length, allowing three or four for the head alone. Its enormous mouth had an aperture two yards in length.
The megalosaurus was a great lizard and a kind of crocodile from fourteen to fifteen yards in length, essentially carnivorous, nourishing itself with reptiles, small crocodiles, and tortoises. Its formidable jawbone was armed with teeth like a double bladed pruning or garden knife bent round behind in such a way, that, once having entered into their prey, it was impossible for the latter to disengage themselves.
The iguanodon (iguana), the largest lizard which had appeared upon the Earth, measured from twenty to twenty-five yards from the head to the extremity of the tail. Its snout was surmounted by a horn formed of bone, similar to the iguana of our day, from which it seem to have differed only in size; the latter having a body not a yard in length. The form of the teeth prove that it was herbivorous, and the feet that it was a land animal.
The pterodactyl was a strange animal of the size of a swan, being like a reptile in body, with the head of a bird. Its toes, which were of a prodigious length, were united with a fleshy membrane like that of the bat, which served it as a parachute when it precipitated itself from the height of a tree or rock upon its prey. It had no horny beak like birds; but the jawbones were as long as half its body, and were garnished with teeth terminating in a point like a beak.
31. During this period, which must have been very long as the number and importance of the geological beds attest, animal life developed largely in the watery elements, in like manner to vegetation in a previous period. The purer air, more conducive to respiration, permits some animal to live upon the Earth. The sea has been many times displaced, but without violent commotion. With this period disappeared in their turn those races of gigantic aquatic animals, replaced later by analogous species, less disproportionate in form, and of infinitely smaller size.
32. Pride has influenced man to say that all animals were created for his purposes and for his needs. But what is the number of those which directly serve him, which he has been able to subject, compared to the incalculable number of those with which he has never had and will never have any connection? How is it possible to sustain a similar thesis in presence of these innumerable species which alone have populated the Earth for thousands and thousands of centuries before he came here himself, and which have disappeared? Can one say that they have been created for his profit? However, these species all had their utility in life. God would not create them for nothing in order to give himself the pleasure of destroying them; for all had life, instincts, and the capacity for misery and happiness. What then was the object? It must have been a sovereignly wise one, though we are still unable to comprehend it. Perhaps the secret will one day be given to man, in order to humble his pride; but in the meantime how many ideas crowd upon us in presence of these new horizons into which we are permitted to gaze, and which display to us the imposing spectacle of this creation, so majestic in its slow and mighty developments, so admirable in its foresight, so punctual, precise, and invariable in its results.