FLYING FLAGONS, 
127 
It was thought at one time that Birds differed 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 
Arch^opteryx, 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. 
