INTRODUCTION. xvii 



no birds on the face of the earth ; when the warm- 

 blooded creature (whether bird or mammal) had not yet 

 been evolved. The oldest known bird, Archceopteryx^ 

 dates from the Jm-assic age ; but it cannot possibly have 

 been the first bird, being in many respects already highly 

 evolved along the avian line. On the other hand, it 

 had many reptilian features — such as the lizard-like 

 tail, the clawed fingers, and the teeth in the jaws — and 

 is one of the striking evidences of the reptilian origin 

 of birds. For in spite of all the apparent dissimilarity 

 between the grovelling reptile and the bird of the air, 

 that the two types are bound together in blood-relationship 

 is proved up to the hilt by detailed resemblances in 

 structure (from such trivial things as the scales on the 

 bird's feet to fundamental agreement in skull-architecture) ; 

 by close resemblances in the development of bird and 

 reptile (for it is not till the sixth day that the un- 

 hatched chick, for instance, leaves a track precisely 

 parallel to that of the unhatched reptile, and di\'erges 

 on a path of its own) ; and by the existence in the distant 

 past of flying reptiles and reptile-like birds. Zoologists 

 are unanimously convinced that birds evolved from some 

 extinct reptilian stock, but from which no one can tell — 

 whether from pterosaurs or dinosaurs, or from an 

 ancestry common to both, or from some other prolific 

 line. In this connection, it may be mentioned that it 

 is by no means to be supposed that the 'finds' of extinct 

 connecting links have come to an end. It may be, for 

 instance, that among the reptilian remains buried in, let 

 us say, the Elgin Sandstones, a clue to the pedigree of 

 birds may yet be found. There can be no doubt, for 

 instance, of the suggestiveness of a remarkable type called 

 Scleromochlus tayloi-i, recently discovered by Mr William 

 Taylor of Lhanbryde, a naturalist of wide scientific 



