igo 



THE ORIGIN AND EVOLUTION OF LIFE 



Permian into the Upper Triassic. Here, up to the year 1909, 

 twenty-two species of fossil fishes had been recorded, mostly 

 ganoids of Triassic age. The eleven species of amphibians dis- 

 covered are of the solid-headed (Stegocephalia) type, broadly 



similar in external appearance to 

 those of the same age discovered 

 in Europe. The one hundred and 

 fifteen species of reptiles described 

 from the Lower and Middle Per- 

 mian deposits include solid-headed 

 pareiasaurs — great, round-bodied, 

 herbivorous reptiles with massive 

 limbs and round heads — which are 

 allied to the cotylosaurs of the 

 Permo-Carboniferous of America, 

 the agile dromosaurs, similar to the 

 lizard-like reptiles of the Texas 

 Permian, with large eye-sockets, 

 and adapted to swift, cursorial 

 movements, also reptiles known 

 as therocephalians in reference to 

 the analogy which the skull bears 

 to that of the mammals, gorganop- 

 sians, and numerous slender- 

 limbed, predatory reptiles with 

 sharp caniniform teeth. The giant 

 predaceous Reptilia of the time 

 are the dinocephalians (z. e., "terri- 

 ble-headed"), very massive animals with a highly arched back, 

 broad, swollen forehead, short, wide jaws provided with mar- 

 ginal teeth. Surpassing these in size are the anomodonts {i. c, 

 "lawless-toothed") in which the skull ranges from a couple 



Fig. 70. Mammal-like Reptiles of 

 South Africa. 



The relative stability of the African 

 continent favored the early evolu- 

 tion of the free-limbed forms of 

 reptiles known as Anomodonts, in- 

 cluding the powerful Eudothiodon, 

 in which the jaws are sheathed in 

 horn like those of turtles; and also 

 of the Cynodonts (dog-toothed 

 reptiles), including the carnivorous, 

 strongly toothed Cynognalhiis which 

 is allied to the ancestors of the 

 Mammalia. Restorations for the 

 author by W. K. Gregory and 

 Richard Deckert. 



