122 ANIMAL LIFE PAST AND PRESENT. 



nodon ; these mutual resemblances and differences thus 

 serving to indicate that the latter has probably been de- 

 rived from reptiles more closely resembling crocodiles. 



The teeth of the Hoplosaur, although so unlike those 

 of the Iguanodon, likewise indicate that their owners 

 were of herbivorous habits. The gigantic bulk of these 

 creatures is indicated not only by the arm-bone men- 

 tioned above, but also by another arm-bone obtained 

 from the Kimeridge clay, which measures 57 inches in 

 length, as well as by the thigh-bone of the allied 

 Cetiosaur (whale-lizard) from the still older Stonesfield 

 slate of Oxfordshire, which is upwards of 64 inches 

 in length. The latter dimensions stupendous as they 

 seem are, however, exceeded by another^tlngh-bone 

 from the United States, which actually measures up- 

 wards of 74 inches, or 6 feet 2 inches in length. The 

 owner of this enormous bone has been appropriately 

 named the Atlantosaur, and appears to have been the 

 largest land animal yet known, alongside of which a 

 full-grown elephant would be a mere pigmy. The total 

 length of another nearly related but somewhat smaller 

 American species known as the Brontosaur is, indeed, 

 estimated to have been as much as 80 feet. 



Another peculiarity of these gigantic reptiles, which 

 must not be passed over, occurs in the structure of the 

 joints of the backbone, or vertebrae. In creatures of 

 such enormous bulk, if the vertebrae were solid their 

 weight would probably be an impediment to the free 

 movements of the body; and we accordingly find 

 that these vertebrae were excavated into large hollow 



