The Development of the Animal World 79 



Moreover, we shall see in the next chapter that there is, 

 in their embryonic development, a most indisputable 

 indication that all the existing birds and mammals had 

 a remote fish ancestor. For the moment we must 

 briefly trace the line of development of the vertebrate 

 land animals. 



From the Carboniferous swamps, with moderate-sized 

 amphibia waddling through the mud, we pass on to the 

 brighter Triassic landscapes. Much larger amphibia 



Giant Reptile of the Jurassic Period 

 (Ceratosaurus) 



now wander at the edge of the waters— the Mastodon- 

 saurus with its great flat head measuring three feet by 

 two, and the Labyrinthodon with teeth measuring three 

 and a half by one and a half inches at the base. But a 

 new type of animal — the reptile — has appeared, and we 

 have plenty of evidence that it is evolved from the 

 amphibian. There is the Rhyncosaurus, with great 



