Essay on the Theory of the Earth

by baron Georges Cuvier

How should it be thought, after this, that the huge mastodons and gigantic megatheria, whose bones have been discovered under ground in North and South America, still exist alive on that continent? How should they have escaped those wandering tribes which continually traverse the country in all directions, and which are themselves aware that these animals no longer exist, since they have invented a fabulous account of their destruction, alleging that they were killed by the Great Spirit, to prevent them from extirpating the human race. But it is evident that this fable has been occasioned by the discovery of the bones, like that of the inhabitants of Siberia with respect to their mammoth, which they pretend to live under ground like the mole, and, like all those of the ancients, about the graves of giants, who were thought by them to have been buried wherever the bones of elephants were discovered.

Thus it may safely be concluded, that if, as we have just said, none of the large species of quadrupeds whose remains are at the present day found in regular mineral strata, bear resemblance to any of the known living species, this is not the effect of mere chance, nor because those species of which we possess nothing but the bones, are still concealed in the deserts, and have hitherto eluded the observation of travellers. On the contrary, this phenomenon must be regarded as resulting from general causes; and its investigation may be considered as affording one of the best means for discovering the nature of these causes.

Difficulty of determining the Fossil Bones of Quadrupeds.

If this study is more satisfactory in its results than that of other fossil remains of animals, it is also beset with more numerous difficulties. Fossil shells usually present themselves in an entire state, and with all the characters requisite for comparing them with their analogous species, preserved in the collections or figured in the works of naturalists. Even fishes present their skeleton more or less entire; the general form of their body is almost always distinguishable, and most commonly, also, their generic and specific characters, which are drawn from their solid parts. In quadrupeds, on the contrary, even should the skeleton be found entire, it would be difficult to apply to it characters derived, for the most part, from the hair, the colours, and other marks which have disappeared previous to their incrustation. It is even excessively rare to find a fossil skeleton approaching in any considerable degree to a complete state. The strata, for the most part, only contain separate bones, scattered confusedly, and almost always broken, and reduced to fragments; and these constitute the only resources of knowledge to the naturalist in this department. It may also be stated, that most observers, deterred by these difficulties, have passed slightly over the fossil bones of quadrupeds; have classed them in a vague manner, according to superficial resemblances, or have not even ventured to assign them a name; so that this part of the history of fossil remains, although the most important and most instructive of all, is, at the same time, that which has been the least cultivated[81].

Principle by which this determination is effected.

Fortunately, comparative anatomy possesses a principle, which, when properly developed, enables us to surmount all the obstacles. This principle consists in the mutual relation of forms in organised beings, by means of which, each species may be determined, with perfect certainty, by any fragment of any of its parts.

Every organised being forms a whole,—a peculiar system of its own, the parts of which mutually correspond, and concur in producing the same definitive action, by a reciprocal reaction. None of these parts can change in form, without the others also changing; and consequently, each of them, taken separately, indicates and ascertains all the others.

Thus, if the intestines of an animal are so organised as to be fitted for the digestion of flesh only, and that flesh recent, it is necessary that its jaws be so constructed as to fit them for devouring live prey; its claws for seizing and tearing it; its teeth for cutting and dividing it; the whole system of its organs of motion, for pursuing and overtaking it; and its organs of sense for discovering it at a distance. It is even requisite that nature have placed in its brain the instinct necessary for teaching it to conceal itself, and to lay snares for its victims.

Such are the general conditions which nature imposes upon the structure of carnivorous animals; and which every animal of this description must indispensably combine in its constitution, for without them its race could not subsist. But subordinate to these general conditions, there exist others, having relation to the size, the species, and the haunts of the prey for which the animal is adapted; and from each of these particular conditions, there result modifications of detail in the forms which arise from the general conditions. Thus not only the class, but the order, the genus, and even the species, are found expressed in the form of each part.