We have in it a most instructive combination of the characters of
the bird and the reptile. The feathers alone, the imprint of
which is excellently preserved in the fine limestone, would
indicate its bird nature, but other anatomical distinctions are
clearly seen in it. "There is," says Dr. Woodward, "a typical
bird's 'merrythought' between the wings, and the hind leg is
exactly that of a perching bird." In other words, it has the
shoulder-girdle and four-toed foot, as well as the feathers, of a
bird. On the other hand, it has a long tail (instead of a
terminal tuft of feathers as in the bird) consisting of
twenty-one vertebrae, with the feathers springing in pairs from
either side; it has biconcave vertebrae, like the fishes,
amphibia, and reptiles; it has teeth in its jaws; and it has
three complete fingers, free and clawed, on its front limbs.
As in the living Peripatus, therefore, we have here a very
valuable connecting link between two very different types of
organisms. It is clear that one of the smaller reptiles--the
Archaeopteryx is between a pigeon and a crow in size--of the
Triassic period was the ancestor of the birds. Its most
conspicuous distinction was that it developed a coat of feathers.
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