82 Proiessoi" Owen o)i Ih-lfish Foxsil Jhptiles, 



were contrasted, in reference to their relative a])proximation 

 to the vertebral structure of the higher animals, the resem- 

 blance of the ball and socket joints of the spine of the Strep- 

 tospondylus to those of certain mammals would give prece- 

 dence in organic perfection to the primeval Gavial. 



If, therefore, the extinct species, in which the reptilian or- 

 ganization culminated, were on the march of development to 

 a higher type, the Me(/alosaurus ought to have given origin to 

 the carnivorous mammalia, and the herbivorous should have 

 been derived from the Iguanodon, But where is the trace of 

 such mammalia in the strata immediately succeeding those in 

 which we lose sight of the relics of the great Dinosaurian rep- 

 tiles % Or where, indeed, can any mammiferous animal be 

 pointed out whose organization can, by any ingenuity or li- 

 cence of conjecture, be derived without violation of all known 

 anatomical and physiological principles, from transmutation 

 or progressive development of the highest reptiles. 



If something more than a slight inspection be bestowed 

 upon the organic relics deposited in the crust of the globe, we 

 learn that the introduction of the mammalia on that crust is 

 independent of the appearance of the highest forms of reptiles. 

 Tlie small insectivorous mammals of the lower oolite* are 

 contemporary with the most ancient Dinosaur, and are ante- 

 rior to the Iguanodon. 



The period when the class of reptiles flourished under the 

 widest modifications, in the greatest number and of the highest 

 grade of organization, is past ; and, since the extinction of the 

 Dinosaurian order, it has been declining. The reptilia are now 

 in great part superseded by higher classes : Pterodactyles have 

 given way to birds ; Megalosaurs and Iguanodons to carnivo- 

 rous and herbivorous mammalia ; but the sudden extinction 

 of the one, and the abrupt appearance of the other, are alike 

 inexplicable on any known natural causes or analogies. 



New species, genera, and families of reptiles have constantly 



♦ For the proof of the often doubted mammalian character of the Thylaeo- 

 therlum and Phascolotheriuin of the Stonesfield slate, the reader is referred 

 to the memoii-s in the sixth volume of the second series of the Geological 

 TraasactioiiS; pp. 47-58. 



