CONNECTING AND MISSING LINKS 



resented, one by a single feather and the other two by com- 

 plete skeletons, except that one is headless. This headless 

 form, now in the British Museum of Natural History, is the 

 famed Archaeopteryx; the other, in Berlin, shows sufficient 

 distinction in its preserved parts to warrant a new generic 

 name, Archaeornis. Both are classed as birds largely because 

 of the feathers and implied powers of flight; in other respect 

 they are reptiles. Archaeornis, in fact, has been called a rep- 

 tile in the disguise of a bird, and the skull might well belong 

 to a reptile, never to a modern bird. Here a none too effi- 

 cient flight is already attained, but here again the history is 

 missing, and our ideas concerning the origin of bird flight 

 must still remain hypothetical. The scientific visualization 

 of this pro-avian is of a light-built dinosaur-like form, run- 

 ning freely on the hind limbs an,d occasionally taking to trees 

 for soaring leaps, sustained largely by partly modified rep- 

 tilian scales. Out of such a scale in turn would evolve that 

 masterpiece of nature, the feather — a prophecy that may in 

 time be realized by fortunate discovery in the older rocks. 

 From Archaeopteryx to the toothed birds of the Cretaceous 

 period is again a considerable unbridged gap, during which 

 the bird became essentially modernized except for the reten- 

 tion of teeth in the jaws, which may w^ell have been due, 

 however, to a habit of eating fish. We can well imagine 

 intervening stages, showing gradual adaptation to greater 

 efficiency in flying. The shortening of the lizard-like tail of 

 Archaeornis, the feathers of which are arranged in a row on 

 either side, to the fan-like tail of the pigeon or crow produced 

 a vastly better device for manoeuvering in flight. The hand 

 has consolidated the old free grasping fingers into a better 

 and stronger wing, and the skull has changed its character 

 in many details. A succession of drawings comparable to a 

 moving picture film might well be made to show these 



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