LIFE IN SECONDARY TIMES 271 



which Cuvier based his essentially finalistic comparative 

 anatomy. 



We have now studied the wonderful evolution of the land 

 Reptiles. But they did not limit their activity to the invasion 

 of the land. They also acquired wings, probably as a result 

 of the folds of skin similar to those we have already mentioned 

 (p. 130), which formed upon the flanks of tree-climbing varieties 

 in the Secondary Epoch. Unfortunately the transitional forms 

 are unknown. The wing of the Pterosaurians was always con- 

 structed on the same plan. At the back a large membrane ran 

 along the whole length of the sides as far as the end of the tail, 

 and in front spread to the exterior edge of the digits of the fore- 

 limbs, which had become three times as long as the body. 

 Contrary to all that took place in the preceding cases, the 

 enormous head was sometimes one-third as long as the body 

 (Pterodactylas crassirostris) . It was perpendicularly articulated 

 with the neck and its bones united as in Birds, an arrangement 

 which seems to indicate a relation between this condition and 

 rapid aerial locomotion. The jaws carried sharply pointed 

 teeth (Pteranodon) , and were sometimes replaced by a sort of 

 horned beak, of which the termination of the jaws in a point 

 in Ramphorhyncus may be considered an indication. The oldest 

 known remains of a Pterosaurian go back to the Lias of Lyme 

 Regis. This forerunner (Dimorphodon macronyx) of the Pterosaur- 

 ians had a slender tail six decimetres in length, and the body was 

 almost the same length. Omithocheirus of the English Wealden 

 also had a long tail terminating in a kind of membranous rudder ; 

 the teeth were pointed, widely spaced, and inclined forward. 

 On the other hand, their contemporaries, the Pterodactyls, 

 had short tails ; their size fluctuated between that of a Crow 

 and that of a Sparrow. The giant among Pterosaurians was 

 Pteranodon, which spanned six metres and whose dimensions 

 far exceeded those of our largest Condors. It flourished in 

 Kansas during the middle Cretaceous Epoch. They were 

 Insect-eaters ; their long pointed beak did not permit them to 

 tear their prey. Like Bats, they could not rest on the ground 

 in order to capture small animals, or they would have been 

 unable to take flight again. This also applies to all Pterosaurians, 

 which in order to rest were obliged to suspend themselves 

 from the branches of trees by means either of the normal four 

 fingers of the hand, or by the feet. They had then merely to 



