xi THE GEOLOGICAL RECORD 215 



more distinct the details very faintly shown in the original. 

 To the anatomist every bone or fragment of a bone is recog- 

 nisable ; while the unmistakable feathers, and the foot with 

 the increasing number of joints from the inner to the outer 

 toe, are sufficient to show that it is a true bird, notwith- 

 standing its curiously elongated tail feathered on each side. 

 In this specimen there is no sign of the head ; but fortunately 

 another specimen has recently been found, in which the skull 

 is well preserved, and which shows that the beak was armed 

 with teeth (Fig. 71). Later on, in the Cretaceous formation 

 of Kansas, U.S.A., some 

 well-preserved aquatic birds 

 have been found. One is 

 of large size (about 4 feet 

 high), something like a 

 diver, but with flat breast- 

 bone, and therefore prob- 

 ably with rudimentary 

 wings ; another, much FIG. 71. SKULL OF ARCHMOPTERYX 



11 . i . SIEMENSI, SHOWING TEETH. 



smaller, has long wing- 



, i j i i i j From the lithographic stone (Upper Jurassic) 



bones and a deeply keeled of Bavaria . Nat . size . Original in the 



Sternum. The bony tail Berlin Museum. (B.M. Guide.) 



of these is not much longer 



than in living birds, but in both the beaks are toothed. 



The main reason for the extreme rarity of bird-remains 

 in the Mesozoic era is, that being so light in body and 

 plumage they could very rarely be preserved. Those that 

 died in or on the margins of rivers or lakes, or which fell 

 into the water, would be at once devoured by the fishes or 

 the aquatic or aerial reptiles which seem to have swarmed 

 everywhere. 



Concluding Remarks on Mesozoic Life- Development 



The remarkable series of facts which have now been 

 summarised, and which have been largely due to researches 

 in North America, South Africa, and Europe during the last 

 twenty or thirty years, are of such a nature that they seem 

 to call for some cosmical explanation similar to that sug- 

 gested to account for the vast development of cryptogamous 

 vegetation towards the close of the Palaeozoic era. The facts 



