FLYING DRAGONS. 127 



It was thought at one time that Birds dififered from Pterodactyls 

 in the absence of teeth ; but this only holds good for modern 

 birds. If we go back to the Mesozoic age, we find that birds 

 at that time did possess teeth. The oldest known bird, the 

 Archsopteryx, had teeth in its jaws, and presents some very 

 striking points of resemblance to reptiles. But if we compare the 

 skeleton of a Pterodactyl (such as the P. spectabilis, now under 

 consideration) with that of a bird, we shall see in its fore limbs 

 certain very obvious differences. A bird never has more than 

 three fingers in its hand or wing (viz. the thumb and next two 

 digits), and the bones that support these fingers, corresponding to 

 the bones in the palm of a human hand, are joined together. 

 Neither of the bones corresponding to our fingers are much 

 elongated, and of these the longest is that which corresponds to 

 the thumb. But, on referring to the skeleton of our Pterodactyl, 

 we find that it has four fingers, three of which are fairly developed 

 and furnished with claws, while the outermost one is enormously 

 elongated. This is believed to correspond to the little finger of 

 the human hand, while the thumb seems to be represented by a 

 small bone seen at the wrist. It was this long outside finger 

 that chiefly served to support the flying membrane of the Ptero- 

 dactyl. For this and other reasons, we are forbidden to look 

 upon these creatures as relatives of birds. Again, all birds that 

 can fly possess a " merrythought," or furculum ; and such is not 

 found in the Pterodactyl. 



As we have already remarked, some authorities, when these 

 creatures were first brought to light, considered them to be 

 mammals, as bats are. But equally conclusive arguments may 

 be brought forward against that view. All mammals have the 

 skull jointed to the backbone by two articulations, known as 

 " condyles," whereas Pterodactyls have only one — in that respect 

 resembling reptiles and birds. 



Also there are important differences in the structure of their 

 jaws, showing that they are constructed on the reptilian plan, and 

 not on that of the mammal. 



