CROCODILIA 



order. And, more recently, it has 

 also become quite apparent that the 

 old crocodiles should not be separated 

 so widely from the modern ones as 

 Huxley proposed; that the differences 

 distinguishing them from the recent 

 members of the order are really not 

 of more than family importance. We 

 thus have left but two chief divisions 

 of the Crocodilia, the Eusuchia and 

 Thalattosuchia; and the latter group 

 even, by some authors, perhaps rightly, 

 are included under the true crocodiles 

 as a family only. 



These older crocodiles, the Meso- 

 suchia of Huxley, comprise a con- 

 siderable number of extinct forms 

 which lived as far back as the early 

 part of the Jurassic, and continued 

 nearly to, if not actually into, Ceno- 

 zoic time, that is, to the Eocene. 

 They differ from all living forms, 

 chiefly in having, not concavo-convex 

 but biconcave backbones, that is, the 

 more primitive vertebrae with which 

 all reptiles began. Nor was the inter- 

 nal opening of the nasal passages so 

 far back in the mouth as in the later 

 forms. In other respects they did 

 not differ very greatly from some of 

 those now living. All the earliest 

 kinds that we know of — the teleosaurs 

 — had a long, slender snout, resem- 

 bling very much that of the modern 

 gavials. And they were, for the most 

 part, incased in a more complete bony 

 armor, on both the dorsal and the 

 ventral sides; and the front legs were 



205 



Fig. 106.- 

 from above. 



-Teleosaurus; skull, 



