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Page:Popular Science Monthly Volume 18.djvu/641

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future would have prevented his seeing any promise beyond. But prophetic indications always become plainer after their fulfillment, and so we, by the aid of all subsequent life-history, are able to read in the structure of the Carboniferous reptiles the promise of better things. As the age draws on to its close, certain characters become more and more pronounced in some of the old, half-formed crocodiles, while a totally different set of peculiarities come to the front in others. Taking the whole group together, we find a very wide range of affinities indicated. One of these points by unmistakable signs to the dinosaurs—great, biped, bird-like reptiles that became conspicuous in the age following the coal. From these the passage is direct to the reptilian birds of the same age, so like dinosaurs in many particulars that they can hardly be distinguished. Then follows, after delay and successive changes of form reaching over geologic periods, the real bird type of our woods and fields, marvelous in its perfect adaptations and marvelous in its perfect symmetry and beauty.

But some of those old reptiles are fraught with suggestions of still higher meaning. In some of the groups recently brought to light from strata that mark the closing epochs of the Carboniferous age, the coming mammal is very plainly indicated. And so, if we only read aright, we may find in our piece of coal the suggestion and the promise of even the highest forms of life.

So it is that we have a very direct interest in that old coal age, an interest altogether independent of the coal itself, even though we know that modern industry and commerce and civilization, and the great centers of human population—the manufacturing and commercial cities, with all their wealth and magnificence—are directly dependent upon its marvelous stores of energy. The physicist will tell us how that energy, which drives our engines, warms and lights our rooms and makes it possible for us to sit here in comfort and never miss the light of the sun to-night, is simply so much force derived from the sunbeams of the Carboniferous age, invested for our benefit in the old ferns and club-mosses; and yet our interest in the coal rises above all this. The roots of the present strike very deeply into the past, and nothing is risked in saying that, had the Carboniferous age, in its strangely constituted life-forms or in any other regard, been different in ever so small a degree, the present would not be just what it is. It is away back in the coal that we find, not only the promise of the grandly diversified system of vegetable life that lends so much of beauty and interest to the age in which we live; but it was then, also, that manifest preparations were made for bringing upon the scene the various specialized groups of animals that are to-day a matter of personal concern to every one of us. It was in the coal, too, that we found the first real evident but rude shapings of the organic frame which we ourselves wear. Hugh Miller—an authority that may be safely introduced on this occasion—was accustomed to quote approv-