160 WATER REPTILES OF THE PAST AND PRESENT 



quite like the adjacent ones, by the loss of the ribs connecting them 

 with the ilium. The small pelvis was suspended loosely in the 

 walls of the abdomen, or at the most was feebly connected with 

 a single vertebra by ligaments. It was entirely useless as a support 

 for the legs. The mosasaurs could not possibly have raised their 

 bodies from the ground while on land. It is well known that the 

 land lizards and the crocodiles raise their bodies free from the ground 

 while running or walking; none drags its body over the surface. 



In several instances complete or nearly complete skeletons of 

 mosasaurs have been discovered with the different bones nearly 

 all in the positions and relations they had after the decomposition 

 of the flesh, together with the carbonized remains of the skin and 



SH 



'■-T&-. 



Fig. 78. — Photograph of carbonized remains of scales of Tylosaurus, natural size 



impressions of the investing scales and membranes. The nature 

 of the body covering is therefore known with certainty from nearly 

 all parts of the body. The body everywhere, save on the mem- 

 brane between the fingers and toes, and perhaps on the top of the 

 skull, was covered with small overlapping scales, very much like 

 those of the monitors. These scales, however, were small and 

 smooth in comparison with the size of the animals, those of a 

 mosasaur twenty feet in length being almost precisely the size 

 of those of a monitor six feet long. The top of the skull seems to 

 have been covered with horny plates, as in most lizards. In one 

 instance parallel dark bars, obliquely placed, and of narrow width, 

 formed by carbonized pigment, were observed by the writer. As 

 has been stated, in some instances fish bones and fish scales have 



