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Page:Popular Science Monthly Volume 24.djvu/628

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THE POPULAR SCIENCE MONTHLY.

ness. Most interesting of all for our present purpose, however, are the bones of contemporary reptiles and birds which this Nature-printing rock incloses for the behoof of modern naturalists. One such reptile, known as compsognathus, may be regarded as filling among its own class the place filled among existing mammals by the kangaroo. It was a rather swan-like, erect saurian, standing gracefully on its hind-paws, with its fore-legs free, and probably dragging its round tail behind it on the ground as a support to steady its gait. The neck was long and arched, and the head small and bird-like in shape; but the jaws are armed with sharp and powerful teeth, as in the pterodactyls. Altogether, compsognathus must have looked in outward appearance not at all unlike such birds as the auks and penguins, though its real structural affinities lie rather with the emus and cassowaries. The apteryx or kiwi of New Zealand, which is a bird that does not fly, because it has no wings worth mentioning to fly with, approaches even nearer in the combination of both points to this very bird-like oőlitic reptile.

Even compsognathus himself, however, though very closely allied to the true birds, can not be held to stand as an actual point in the progressive pedigree, because in the very same Solenhofen slates we find a real feathered bird in person. Accordingly, as the two were thus contemporaries, the one could not possibly be the direct ancestor of the other. Nevertheless, it is certainly from some form very closely resembling compsognathus that the true birds are descended. We have only to suppose such a reptile to acquire forestine habits, and to begin jumping freely from tree to tree, in order to set up the series of changes by which a true bird might be produced. But the first historical bird of which we know anything, the archæopteryx of the Solenhofen slate, still remains in many points essentially a reptile. It is only bird-like in two main particulars; its possession of rudimentary wings and its possession of feathers. From the popular point of view, these two particulars are decisive in favor of its being considered a bird; but its anatomical structure is sufficient to make it at least half a reptile; and eminent authorities have differed (with their usual acrimony) as to whether it ought properly to be called a bird-like saurian or a lizard-like bird. There is nothing like a mere question of words such as this to set scientific men or theologians roundly by the ears for half a century together.

Archæopteryx, then, is just compsognathus provided with rude wings and feathers, but in most other respects a good lizard. Unlike all modern birds, it has a long tail composed of twenty separate vertebræ; and opposite each vertebra stand two stout quill-feathers, so that instead of forming a fan, as in our own pigeons and turkeys, they form a long pinnate series like the leaflets of yonder palm-branch. These feathers, like all others, show traces of their origin from the scales of lizards. Moreover, in the jaw are planted some small conical