PLANTS 



485 



Queensland, where they are chiefly Lower Cretaceous and contain 

 coal. The New Zealand Cretaceous is also coal-bearing. 



Cretaceous Life 



The life of the Cretaceous displays so great an advance over that 

 of the Jurassic that the change may fairly be called a revolution. 



Plants. — If the separation between the Mesozoic and Cenozoic 

 eras were made entirely with reference to the plants, it would pass 



FIG. 159. — Cretaceous leaves, Dakota stage. 1. Dammarites emarginatus, 1/2. 

 2. Betulites Westi, 3/4. 3. Liriodendron giganteum, 1/2. (After Lesquereux.) 



between the Jurassic and the Cretaceous, just as a similar criterion 

 would remove the Upper Permian to the Meozoic (see p. 432). 

 The vegetation of the Lower Cretaceous, especially of the lowest, 

 is still much like that of the Jura. Ferns, Horsetails, Cycads, and 

 Conifers continue to make up most of the flora, but the impend- 

 ing revolution is announced by the appearance of Dicotyledons of 

 archaic and primitive type. In the higher parts of the Potomac 

 the Cycads become much less abundant and the Dicotyledons very 

 much more so. Here we find many leaves which belong to genera 

 that cannot be distinguished from those of modern forest trees, 

 such as Sassafras, Populus, Li?'iode?idron, etc. No Dicotyledons 



