306 OUTLINES OF EVOLUTIONAEY BIOLOGY 



such delicate structures as feathers. This animal was about the 

 size of a rook and the presence of well developed feathers and 

 wings of the avian type is alone sufficient to show that we are 

 dealing with a true bird. It still exhibits, however, a number of 

 features which are usually met with in reptiles but have dis- 

 appeared in modern birds. The digits of the anterior limb are 

 not nearly so much reduced as in the latter, for three claw-bearing 



FIG. 151. Fossil Remains of Arcliceopteryx siemensi, showing the three 

 fingers in each wing, the long tail, feathers, &c. (From Lankester's 

 " Extinct Animals.") 



fingers project from the anterior margin of the wing ; the tail is 

 elongated like that of a lizard and supported by about twenty 

 separate vertebrae each carrying a pair of feathers ; and numerous 

 teeth are present in the beak. 



It is obvious that Archaeopteryx represents a stage in the 

 derivation of birds from reptilian ancestors, and this is exactly 

 what we should expect of the earliest birds in accordance with 

 the theory of evolution. Unfortunately, with the exception of a 

 few other toothed birds of Cretaceous date, Archaeopteryx is 



