106 BXTINCT MONSTERS 
deal of confusion and trouble in the end; and, moreover, would be 
far more truly scientific. For what right has any one, however 
great his knowledge or his ability, to dictate to Nature, and to 
say this or that is impossible—that no reptile, for instance, 
could possibly have flown; or that such and such teeth were 
impossible for a reptile ? 
We now know that there was a time when certain reptiles 
did fly (although many people with some pretensions to know- 
ledge doubted the evidence). And so with regard to reptilian 
teeth ; fossil evidence shows that some old reptiles had teeth 
more like those of modern mammals! Facts such as these 
should teach caution, and every student of paleontology will 
do well to remember the saying of Agassiz: “The possibilities 
of existence run so deeply into the extravagant that there is 
scarcely any conception too extraordinary for Nature to realise.” 
The chief characters of the Anomodonts may be briefly stated 
as follows: In this order the body is lizard-like, and the limbs 
are adapted for walking. The skull is comparatively short, and 
the nasal openings are large. The teeth are generally placed in 
distinct sockets (thecodont). The bodies of the vertebre are 
hollow at both ends (amphiccelous), and in some cases are only 
partly converted into bone—a character which is common to the 
Labyrinthodonts. The whole structure of the foot is distinctly 
on the mammalian plan. Recent researches show that these 
animals are descended from Labyrinthodonts; and more especially 
the family of which Archegosaurus is a member (see p. 96). 
Certain important characters show (strange as it may seem) 
affinity with mammals; and it is probable that they are related 
to the lowest group of them, as represented at the present day 
by that remarkable creature the Spiny Ant-eater of Australia 
(Echidna), and the wonderful Duck-mole (Ornithorhynchus), 
