96 REPTILES 



such as Compsognathus tongipes, from the Upper Jurassic 

 lithographic limestone of Bavaria and Ornithomtmus nit us of 

 the Cretaceous rocks of North America ; and it has consequently 

 been suggested that the frilled lizard has inherited the upright 

 posture and running gait from dinosaurian ancestors. Nothing 

 could be further from the truth, lizards being widely sundered 

 from dinosaurs. The acquisition of the running habit in the 

 frilled lizards, in certain iguanas, and in the carnivorous dino- 

 saurs, on the contrary, is another instance of the independent 

 development of similar adaptations. From a study of the 

 skeleton of the fore-limb of the dinosaur Ornithomimus palaeon- 

 tologists have come to the conclusion that the fore-foot was en- 

 dowed with grasping and seizing power and consequently 

 capable of acting as a hand ; and since these reptiles, from the 

 structure of their teeth, were evidently carnivorous, it has been 

 suggested that they were in the habit of capturing on the wing 

 the contemporary lizard-tailed birds, such as Archcropteryx, 

 whose flight was probably slow, heavy, and low. 



From the foregoing cursorial type, in which the upright 

 posture was assumed either occasionally or permanently, the 

 transition is easy to the giant herbivorous dinosaurs, such as 

 Iguanodon of the European Wealden and a number of allied 

 forms from the Upper Jurassic and Cretaceous strata of North 

 America, in which the bipedal posture was habitual, although 

 the gait was a walk, as is indicated by the impressions of the 

 footsteps of these reptiles found in the sandstone of Hastings. 

 The larger kinds of iguanodon (which take their name from a 

 fancied resemblance between their teeth and those of modern 

 iguanas) stood approximately twenty feet in height, and 

 walked on their hind-limbs, with perhaps some support from 

 the long and heavy tail, which probably acted as a counter- 

 poise to the head and fore part of the body. Apparently the 

 general shape of the trunk approximated more or less closely 

 to the compressed arboreal type, although there may have been 

 some greater degree of expansion in the region of the chest to 

 allow of the free play of the fore-limbs which were evidently 

 used as arms. The iguanodons and their allies were by no 

 means the only large dinosaurs which habitually walked in the 

 upright posture. The carnivorous Megalosaurus, for example, 

 which when in this posture stood about a dozen feet in height, 



