Aprii.. 1929 



EVOLUTION 



Page Five 



Dragons of the Air 



By FREDERIC A. LUCAS 



VV'HEN the Mosasaurs were the rulers of the .seas, 

 the Pterodactyls or flying reptiles had for ages 

 held the empire of the air. For in the Jurassic, when 

 hirds in the shape of Archeopteryx were just beginning 

 to flutter, pterodactyls had long since solved the prob- 

 lem of flight and were present, big and little, in swarms. 

 They must have been particularly abundant about the 

 Solenhofen Sea of Central Europe whose soft, muddy 

 bottom, long ago hardened to rock, furnishes the best 

 lithographic stone, for in this stone beautifully pre- 

 served by nature's lithography, many species occur. 



Just as Pterodactyls played the part of birds as re- 

 gards flight, so they seem like the liirds to have been 

 creatures of varying size and diverse habits. Some 

 were big as an albatross and sailed majestically over 

 the sea, while others, no bigger than a sparrow, flew 

 merrily over the land in pursuit of insects. There were 

 pterodactyls with long tails, pterodactyls with short 

 tails and pterodactyls with no tails at all. While some 

 flew by day, others, to judge from the size of their 

 eyes, anticipated the owls and flew 1iy night. As to 

 their covering, the evidence and balance of opinion is 

 that unlike most reptiles, they were scaleless. The 

 appearance of some specimens suggested that the wings 

 were covered with small scales or undeveloped feathers, 

 but examination showed them to be only fine wrinkles.* 



For reasons unknown they were either sparsely rep- 

 resented in North America during the Jurassic period 

 or their favorite cemetery has not come to light : at any 

 rate scarcely any examples have been found and those 

 in fragmentary condition. But later on. in the Cretac- 

 eous, pterodactyls became abundant and in what is 

 now the state of Kansas reached their greatest size in 

 Pteranodon. 



In pterodactyls the wing was formed l)y a memlirane 

 stretched between the little finger and the side of the 

 body. But in Pteranodon this "little" finger was nine 

 feet long, the wings having a spread of from fifteen 

 to twenty feet, the maximum reached liv any flying 

 animal. The condor and albatross are today the largest 

 flying creatures and they have a spread of wings of 

 from nine to twelve feet, but even this is far under 

 that of Pteranodon. 



Structurally, Pteranodon was a marvel of lightness, 

 the great wing bones being scarcely thicker than a sheet 

 of blotting paper, the body little more than an append- 

 age on the wings. For Pteranodon probably did not 

 weigh more than twenty-five pounds, possibly not even 

 that much. Professor Langley was much interested 

 in Pteranodon because not only was it the greatest 

 flying creature but because, as indicated by the limited 

 area for the attachment of wing muscles, its flight 

 was performed with very small expenditure of power. 

 Thus while his model aeroplane, the first that actually 



flew, required one and a half horse-power for its thirty 

 pounds weight, Pteranodon, it is estimated, used but 

 thirty-six thousandths of a horse-power for the same. 

 One feature of pteranodon, the extraordinary crest 

 shown in the picture, has been the cause of much argu- 

 ment : for a time it was even a moot question whether 

 or not it iiad one. Professor Marsh said be did. 



*(Note:- — Prof. Broili of Munich ha.s just described a 

 specimen covered with fine hair, or at least, hair-like struc- 

 tures.) 



Pteranodon, the Giant Flying Reptile 



Professor Williston as vigorously said he didn't, and 

 both were right ; some had huge crests, some had none, 

 and why they did or didn't no one really knows. 

 To add to the many theories, it is here suggested that 

 the presence or absence of a crest was a sexual distinc- 

 tion, or that it may have served as a counterpoise 

 to the long beak : finally, that it does not seem at all 

 necessary that it should have served any useful pur- 

 pose whatever, perhaps being a danger signal that the 

 day of the pterodactyl was drawing to a close. 



Among the interesting problems concerning the 

 pterodactyl is how he carried himself on land, and 

 having come to earth — or sea — how he got under way 

 again, and what did he do with those enormous wings. 

 For his joints indicate that those wings could not be 

 folded snugly about the body like those of a bat or 

 Iiird : from their very size some other method was 

 necessary and it would seem that many of these flying 

 dragons walked with wings pointed upward. But there 

 is no more reason to suppose that all pterodactyls, big 

 and little, behaved alike any more than all birds fly, 

 swim or run alike. 



Lastly, to repeat an oft propounded query, do pter- 

 anodon and the big birds of today mark the limit of 

 size that may be attained by flying creatures, do na- 

 ture's flying machines stop at a weight of twenty-five 

 to forty pounds? It would seem so. 



The .American Museum of Natural History and Yale 

 L^niversity each have a fine, mounted skeleton of pter- 

 anodon, the latter having one of the few pterodactyl 

 specimens showing tlie imprint of the wing membrane. 

 The finest European collection is in Munich. 



