xv. i7 



DINOSAURS 



425 



Triceratops 



Fig. 247. The skeletons of various ornithischian dinosaurs. 

 (Modified after various authors.) 



longed in various ways, giving a structure that perhaps allowed the 

 nostrils to remain above water while the animal was feeding below. 

 These animals reached 30 ft in length and may have supplanted the 

 sauropods as marsh-living forms, possibly when the soft foods gave 

 place to harder plants. 



Other lines of ornithischians became more fully terrestrial and 

 quadrupedal and were mostly heavilv armoured. Thus the stegosaurs 

 of the Jurassic carried immense spines on the back and the tail bore 



