EVIDENCE OF FOSSIL REMAINS 00 



that occupy the position of "hnks" hot ween groups 

 now widely separated by their divergence in evolution 

 from the same ancestors. Perhaps the most famous 

 example is ArchoBopteryx found in a series of slates 

 in Germany. This animal is at once a feathered, 

 flying reptile, and a primitive bird with countless 

 reptilian structures. Its short lu^ad })ossesses lizard- 

 like jaws, all of which bear teeth ; its wings comprise five 

 clawed digits ; its tail is composed of a long series of 

 joints or vertebrae, bearing large feathers in j^airs ; 

 its breastbone is flat and like a plate, thus resembling 

 that of reptiles and differing markedly from the 

 great keeled breastbone of modern flying birds, whose 

 large muscles have necessitated the development 

 of the keel for purposes of firm attachment. In 

 brief, this animal was close to the ]X)int where 

 reptiles and birds parted company in evolution, and 

 although it was a primitive bird, it is in a true sense a 

 '^ missing link" between reptiles and the group of 

 modern birds. Other fossil forms like Hesperornis 

 and Ichthyornis, whose remains occur in the strata of a 

 later date, fill in the gap between Archcroptcryx and 

 the birds at the present time, for among other things 

 they possess teeth which indicate their origin fn)m 

 forms like Archceopteryx, while in other respects they 

 are far nearer the birds of later epochs. That these 

 hnks are not unique is proved by numerous other 

 examples known to science, such as those which connect 

 amphibia and reptiles, ancient reptiles and i)riniitive 

 mammals, as well as those which come between the 

 different orders of certain vertebrate classes. 



In summarizing the foregoing facts, and the larger 



