GIANT REPTILES OF A PAST AGE. 



467 



Post-tertiary. 



Tertiary. 



Cretaceous. 



our nine orders of reptiles five have disappeared entirely, among 

 them just the most powerful ones, and only four are still in exist- 

 ence. Lizards, turtles, snakes, and we crocodiles have found 

 refuge wherever we could, and mammals are met everywhere. 

 And how did they succeed in thus 

 becoming rulers of the earth ? Sim- 

 ply by introducing new-fashioned 

 arms and methods, such as warm 

 blood and developed brains ; and 

 the most thickened bone plates and 

 largest spines of our ancestors 

 proved to be useless in the new 

 kind of warfare." So Alligator 

 Mississippiensis may meditate, and 

 as a furious Apache Indian sur- 

 prises and kills a lonely white squat- 

 ter, so the alligator may rush upon 

 and seize a strolling mammalian 

 dog or pig of the nearest planta- 

 tion. 



The dinosaurs, one of the men- 

 tioned extinct orders of reptiles, 

 were animals living on the land, 

 some of them peaceably feeding on 

 plants, etc. ; others were dangerous 

 carnivores. In form and size they 

 showed differences as considerable 

 as are presented among the existing 

 mammals by the elephant and the 

 mouse. While the smallest known 

 dinosaurs were not larger than a 

 fox, some of them attained a size 

 which is almost fabulous, and a gi- 

 raffe or an elephant would appear 

 as a dwarf in comparison with these 

 monsters. We may obtain a gen- 

 eral idea of many dinosaurs if we 

 imagine an animal like a huge crocodile, but with a smaller 

 head, a longer neck, and posterior legs which are larger than the 

 fore-legs. These larger posterior limbs, in connection with the 

 long strong tail, gave to these animals somewhat the appearance 

 of a kangaroo. Like this latter quadruped, they were occasionally 

 sitting on the hind-legs and the tail, and some of them were prob- 

 ably also walking or hopping on their posterior legs. Instead of 

 starting from a crocodile, we might therefore say : Let us imagine 

 a huge kangaroo, where the difference between fore and hind legs. 



