26 



KNOWLEDGE ♦ 



[Jan. 9, 1885. 



to know what their organisation was, how their circulation 

 was effected, and what their mode of development was, we 

 sliould not hesitate to put them into a class intermediate 

 between that of the mammals and birds and that of the 

 reptiles properly so called. It was toward 1820 that 

 Gideon Mantell found the first bones of dinosaurians 

 in the midst of Tilgate forest, I^le of Wight, in strata 

 which arc referred to the lower portion of the Cretaceous 

 formation, and which are terrestrial and fresh-water ones 

 that mark a transition from the Jurassic to the Cretaceous. 

 These bones, which were very incomplete, were referred by 

 Mantell to an animal of great .size, which he called an 

 igiianodon, as the teeth ofTered certain analogies, as regards 

 form, with those of a lizard of the present time called the 

 iguana. Since that epoch, and especially f-ince a few years 

 back, our knowledge concerning the dino.saurshas peculiarly 

 increased, and we are beginning to get a glimpse, among 

 these animals, of very different types, which indicate orders 

 just as distinct as are those of the pacliyderms, ruminants, 

 and carnivora among mammals. 



Upon the sides of the Rocky Mountains, in the United 

 Htates, we find sti-ata which can be followed for several 

 iinndred miles in extent, and which have yielded for the in- 

 vestigation of paleontologists a small marsupial, remains of 

 Jilies, remains of pterodactyls, crocodiles, and tortoises, and 

 especially an enormous quantity of bones of gigantic dino- 

 saurs. We Imve here a true bone-yaid in which lie buried, 

 pellnielj, the most curious and strange forms of all the 

 animals that the ancient ages have bequeathed to u^. It is 

 to the admirable researches of Marsh and Cope that we owe 

 •Dur knowledge of a fauna that has entirely disappeared. 

 Ouided liy the two great laws of correlation of forms and 

 subordination of characters — laws which we owe to the in- 

 romparable genius of Cuvier, and which, like Ariadne's 

 thread, permit u.s to find our way ,in the inextricable 

 labyrinth that is presented by the forms of extinct animals 

 — these two learned American paleontologist.s have evi ked 

 an entirely new world, and brought up before us the 

 <ividenc6.s of a fauna of which nothing in existing nature 

 could have given ua the least notion. 



Durirg the secondary epoch the dinosaurs lived also in 

 Europe and in Southern Africa, where they were repre- 

 sented by very diverse types, as has been shown us by the 

 learned researches of Mantell, Owen, Phillips, Huxley, 

 Seeley, Hulke, Dollo, and Mitheron. 



Very recent researches have thrown an entirely new light 

 upon the organisation of these animals, and permitted of as 

 complete a study of their skeletons as could hive been 

 made of those of animals now living. We can grasp the 

 general features that connect them with other reptiles, and 

 the peculiar ones that distinguisli them from each other. 



What essentially separates the dino:-aurs from all other 

 reptiles is that the .'^acrum is always composed of more 

 than two vertebra^ which form a very solid single bone, 

 like that of mammal.". These vertebra^, which exceed the 

 normal number of two, are caudal ones that are modified 

 so as to serve as a support of the pelvis, which is consi- 

 derably enlarged, in order to be able to support the usually 

 rubu&t hind limbs. To judge by the great wiilth presented 

 by the medullary canal, the spinal marrow must h^ve been 

 n,uch swollen in the sacral region, and have fumi-hed very 

 hirge nerves to a limb that was strongly developed and 

 moved by extremely powerful muscles. 



The ribs are highly devehiped, and their size shows that 

 the thoracic regioi; was very ample, and that consequently 

 the lungs must have been large. 



As the food of the dinosaurs was very varied, the form 

 of their teeth is, as may be seen, entirely difl'erent according 

 to the types examintd. The llesh-eatcr.-, such as the me- 



galosaurus (Fig. 1), had strong, cutting teeth, which were 

 crenulate at the edges. The maxillarie.", as well as the in- 

 termaxillaries, were armed with such teeth, and these must 



Fif,'. 1.— Tooth of Megalosanrna. Fig. 2. — Tooth of Iguanodon. 



have been formidable. The herbivora, such as the iguano- 

 don (Fig. 2), the vectisaurus, the laosaurus, and the hyp- 

 silophodon, had maxillaries that were provided with teeth 

 admirab'y arranged for cutting and grinding. These teeth 

 became worn out, like those of existing herbivorous mam- 

 mals, and were indefinitely replaced, tljat is to say, as soon 

 as one of them was worn out, another one succeeded it. 

 What is not found in existing reptiles was a motion of the 

 jaws, as in the ruminants of our epoch, in order to allow the 

 teeth to grind food. The size of the apertures and channels 

 through which the nerves passed shows that there existed 

 soft lips and cheek.s, without which the mastication of food 

 would have been entirely impossible. 



The hadrosauri, which were herbivora, had their teeth 

 arranged in several rows that formed, through wear, a 

 grinding surface iu the form of a checker-boaid. In the 

 herbivora which have been grouped under the name of 

 ornithopodia the intermaxillaries were not provideel with 

 teeth, and the fame was the case with the extremity of the 

 lower jaw, which was very likely armed during life with a 

 horny beak ; by means of which the animal cut off' the buds 

 and leaves that constituted its food. 



Many dinosaurs had naked skin. In others, that are 

 designated as stegosauri, the body was protected by bony 

 shields and by spines. 



We are acquainted with dinosaurs of all sizes, from the 

 gigantic atlantosaurus of the Rocky Mountains, which 

 attained a length of at least 80 feet, down to the nano- 

 saurus, which was scarcely as large as a cat. 



The secondary epoch, in which the dinosaurs lived, has 

 justly been entitled the reign of reptiles. It was then that 

 this group reached its maximum development. The 

 mammals were very puny during this epoch, and were 

 represented .solely by the most inferior kinds. The dino- 

 saurs seem to have then played upon the surface of the 

 globe the role that the large carnivora and herbivora 

 do now ; but, while mammals have always gone on im- 

 proving until they already offered at the end of the 

 Tertiary epoch the magnificent development which we now 

 see, reptiles have gone on continuously diminishing in 

 importance. The higher animals have gradually excelled 

 beings of a less perfect organisation. 



Dating from the Triassic epoch, the dinoFaurs were 

 already represented by so diverse types that it seems as if 

 these were the descendants of animals that existed at a 



