. The story of the birds; . Better to say that nothing but a birdgrows feathers. Birds show that their forefathers were among thereptiles by the following characters common to both,and by many others too technical for our discus-sion : The large Q^g noted, found nowhere else exceptin that three-way connecting link between birds,reptiles, and mammals—the duckbill group; by thelack of complete diaphragm below the heart andlungs; by having only a single ball-and-socket jointwhere the head turns on the neck, whereas the mam-mals and amphibians have two ; by many peculiaritiesof structure about the
. The story of the birds; . Better to say that nothing but a birdgrows feathers. Birds show that their forefathers were among thereptiles by the following characters common to both,and by many others too technical for our discus-sion : The large Q^g noted, found nowhere else exceptin that three-way connecting link between birds,reptiles, and mammals—the duckbill group; by thelack of complete diaphragm below the heart andlungs; by having only a single ball-and-socket jointwhere the head turns on the neck, whereas the mam-mals and amphibians have two ; by many peculiaritiesof structure about the head, especially by having thelower jaw connected to the skull by an intervening(quadrate) bone not found in the mammals. So alsothere are peculiar arrangements of the circulatory sys-tem and of the bones of the feet, etc., that are foundonly in these two groups. Finally, as distinctive ofthe groups, they neither pass through a tadpole or in-complete state after birth, as the amphibians, or have THE STORY OF THE Archaeopteryx macroura, Berlin specimen (after Seeley). A BIRDS FOREFATHERS. 5 special glands i^nainrrKB) to nourish their yonng as themammals. While thej differ from each other in the bird hav-ing hot blood and feathers (instead of cold blood andscales), great naturalists are inclined to make one classof the two groups. The oldest bird which we knowof yet is the fossil ArchoBojjteryx, and had not the printof the feathers on its wings, tail, and legs been left inthe rocks along with its bones, it is probable that itwould have been classed simply as a flying lizard. Thinking back over what has been noted, we maysay of the bird that it is— A back-boned, four-limbed, lung-breathing, egg-laying, hot-blooded, feather-covered, upright-walkingcreature, having its fore legs adapted to flight; for,however flightless a bird may be now, there is sufii-cient evidence that it has come out of an ancestrywhose wings were once really complete and useful. Whether all birds
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1897
