SOUTH AFRICAN FOSSIL REPTILES 



FOSSILS EXCAVATED FROM THE BLUE SHALES OF SOUTH 

 AFRICA PROVE REPTILES TO BE THE ANCESTORS OF MAM- 

 MALS. THESE MAMMAL-LIKE REPTILES LIVED 

 MOSTLY BEFORE THE APPEARANCE OF DINO- 

 SAURS, CROCODILES, LIZARDS AND TURTLES 



By Robert Broom 



Late professor of geology and zoology, Victoria College, Stellenbosch, South Africa 



PROBABLY no question is so interesting to biologists as the origin of 

 mammals, and few questions are more interesting to the layman. 

 Up to 1859 when Darwin published the Origin of Species very few 

 worried much about the origin of anything. The prevailing belief was that 

 somewhere about the year 4004 B. c. the Almighty created all animal forms 

 just as we find them to-day. A few scientists had before this time come to 

 the conclusion from their examination of the fossils found in the rocks that 

 there were serious difficulties in the old view, and many attempts were made 

 to harmonize the scientific facts with the old traditions, but for the most part 

 those who held views differing from their fathers were cautious in expressing 

 them. After 1859 the full and free discussion of the problems gradually 

 led to a general belief in evolution and scientists began to try to trace lines 

 of descent. With some groups the lines of evolution were fairly manifest 

 but with the warm-blooded animals the case presented the greatest difficulty. 

 No other forms seemed at all nearly allied and while it was natural to assume 

 that they must either have sprung from lizard-like reptiles or salamander- 

 like amphibians, there was no clear evidence to decide the question. 



In 1876 Owen in describing the fossil reptiles of South Africa pointed out 

 numerous mammal-like characters seen in them and in 1880 definitely ex- 

 pressed the view that the primitive mammals living to-day in Australia are 

 the direct descendants of a reptilian ancestor such as he had described. 

 Huxley on the other hand favored the descent of the mammals from a sala- 

 mander-like form and the contest between those who believe them de- 

 scended from amphibians and those who look on reptiles as the ancestors 

 has been waged ever since — sometimes rather vigorously. 



When Cope in 1880 studied the remarkable Pelycosaurs, fin-backed 

 reptiles found in the old Permian rocks of New Mexico and Texas, he came 

 to the conclusion that he had found, if not the mammalian ancestors, at 

 least forms allied to them, and in this I believe he was quite correct. 



Between 1888 and 1905 Professor Osborn published a considerable num- 

 ber of papers dealing with the origin of mammals in which he argued that the 

 ancestor of the mammal was probably a member of that group of very 

 mammal-like reptiles found in South Africa and called Cynodonts. This 

 view of Osborn's seems at first sight opposed to that of Cope's but in all 



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