MESOZOIC AGE 



CRETACEOUS PERIOD 



DINOSAURS THE reptile boom was now subsiding. Dinosaurs, it is true, 

 continued fairly prosperous for some time. They had, 

 however, passed their zenith, and soon after the early part 

 of the Period their decline was somewhat rapid. Many 

 changes were going on in the world ; and the animals had 

 become too slow in adaptation. They appear to have found 

 some relief from high pressure by migrations. Not only in 

 North America and Europe were they now living, but some 

 had found their way to South America and India. And on 

 eastern lands in Africa, just south of the equator, some huge 

 forms were sprawling about with limb-bones twice the size of 

 those of the great Diplodocus. 



Among the vegetarians, none of the Diplodocus family 

 were now to be seen ; and only a few comparatively small 

 forms represented the Atlantosauridce famous, in Jurassic 

 times, for creatures of extensive dimensions. Stegosaurus 

 had left no descendants : but Polacanthus was no unworthy 

 representative of the type. This animal standing between 

 three and four feet in height had the anterior half of its 

 back protected by a double row of erect plates in Stego- 

 saurian style. The rest of the dorsal armour consisted of a 

 large shield. The tail bore ten pairs of bony spikes similar to 

 those of the Jurassic monster. 



Other remarkable dinosaurs, flourishing in the early 

 Cretaceous, are known as Iguanodonts, as their teeth re- 

 sembled those of the Iguana lizard. Remains of the animals 

 have been found in England, Belgium, and Germany. They 

 were big bird-footed creatures, standing in some cases fifteen 

 feet in height. In general appearance these veritable Gogs 



