CONTENTS 17 



CHAPTER XX 

 THE MESOZOIC ERA: THE AGE OF REPTILES 



PAGE 



Subdivisions of the Mesozoic 508 



Physical Geography during the Mesozoic 508 



Triassic 508 



Atlantic and Gulf Coasts. Western Interior. Pacific Coast. Triassic 

 in Other Continents. 



Jurassic 512 



Atlantic and Gulf Coasts. Western Interior. Mountain Forming in the 

 West. Jurassic of Other Continents. 



Lower Cretaceous (Comanchean) 514 



Atlantic and Gulf Coasts. Western Interior. Pacific Coast. Lower Creta- 

 ceous of Other Continents. 



Upper Cretaceous (Cretaceous) 516 



Atlantic and Gulf Coasts. Pacific Coast. Western Interior. Upper 

 Cretaceous of Other Continents. The Cretaceous Peneplain. Moun- 

 tain-making Movements at the Close of the Mesozoic. Duration of 

 the Mesozoic. 



Life of the Mesozoic 521 



Comparison of the Life of the Paleozoic and the Mesozoic. Plan of Study. 



Invertebrates 523 



Chalk. Sponges. Corals. Crinoids. Sea Urchins (Echinoids). Starfish. 

 Brachiopods. Pelecypods. Gastropods. Cephalopods. Ammonites. 

 Naked Cephalopods (Belemnites). Crustaceans. Insects. 



Fishes and Amphibians 533 



Reptiles 536 



Reptiles with Mammalian Characters. 



Dinosaurs 539 



Carnivorous Dinosaurs. Unarmored Quadrupedal Dinosaurs (Sauropoda). 

 Unarmored Bipedal Herbivorous Dinosaurs (Unarmored Predentata). 

 Armored Dinosaurs (Armored Predentata). Summary of Dinosaurs. 

 Migration and Extinction of Dinosaurs. Size as a Factor in Ex- 

 tinction. 



Crocodiles 552 



Marine Reptiles 552 



Ichthyosaurus. Plesiosaurus. Mosasaurus (Sea Lizards). Turtles. 



Flying Reptiles (Pterosaurs) . 558 



Toothed Bhids 560 



Archaeopteryx. Hesperornis. Ichthyornis. 



Mammals 563 



Plants 565 



Horsetails. Cycads. Ferns. Gymnosperms. Angiosperms. 



Climate . 569 



Triassic. Jurassic. Cretaceous. 



Coat, 571 



Triassic. Cretaceous. 



