THE ORIGIN OF ANIMAL SPECIES 463 



Archceopteryx, which occupies a position between the 

 reptiles and the birds. Its fossil remains show its 

 reptilian characters in the separate digits on the fore limb, 

 the elongated tail consisting of many vertebrae, and the 

 well-developed teeth in each jaw. Its most prominent 

 avian features were its wings and covering of feathers. 

 The discovery of extinct toothed birds served to make 

 the connection between birds and reptiles complete. 



(5) Evidence from Geographical Distribution. When 

 the faunas of the different continents are compared, 

 they are found to be very unlike. Even in those re- 

 gions which have much the same climate and other 

 physical conditions, as South Africa, South America, 

 and Australia, the faunas are not correspondingly simi- 

 lar. On the other hand, when the animals inhabiting 

 the northern part of South America are compared with 

 those living in the southern portion, there are found to 

 be closer resemblances than in the instances just noted, 

 even though the climatal differences are much greater. 

 A similar statement could be made regarding other 

 great continental areas. There is no native species 

 of mammal common to Europe, America, and Australia, 

 though introduced species thrive. Rabbits, for example, 

 taken from Europe to Australia have multiplied to such 

 an extent as to have become veritable pests. Evidently 

 differences of climate do not alone account for the pres- 

 ent geographical distribution of animals. Great barriers, 

 as oceans, lofty mountain ranges, and deserts, separate 

 faunas, though the differences are not so great as in the 

 case of distinct continents. Again, while it is noted that 

 different regions of a continent are inhabited by distinct 

 species, it is found that these species are more nearly 

 related among themselves than to the species of other 

 continents. For instance, the humming birds, near rela- 

 tives of the sunbirds of Africa and Asia, number about 



