DEINOSAURIA. 



377 



The Deinosauria are exclusively Mesozoic, ranging from the 

 Triassic to the Cretaceous formation, but abounding especially 

 in the Oolitic and the 

 earlier portion of the Cre- 

 taceous period. By Pro- 

 fessor Huxley the " The- 

 codont" Reptiles are re- 

 garded as belonging here, 

 as has been already re- 

 marked. The same high 

 authority has also pro- 

 posed the establishment 

 of a new order termed 

 Ornithoscelida to include 

 the ordinary Deinosaurian 

 Reptiles along with the 

 singular Compsognathus. 



A large number of gen- 

 eric types are included in 

 the Deinosauria, of which 

 Iguanodon, Megalosaurus, 

 Cetiosaurus, and Compsog- 

 nathus may be especially 

 mentioned. Other less 

 important forms are Poi- 

 kilopleuron, Lcelaps, Euske- 

 lesaurus, Hylceosaurus, Hy- 

 psilophodon, and Hadro- 



SaUrUS. Fig 32S ._/^ O j Deinosaur. il Ilium ; is 



The Iguanodon is main- Ischium ;/ Femur ; / Tibia ; 5 Fibula ; as Astra- 



i -r i i /". galus ; ca Calcaneum ; m Metatarsus. (After 



ly, if not exclusively, Cre- Huxley.) 

 taceous, being especially 



characteristic of the great delta-deposit of the Wealden. The 

 length of the Iguanodon has been estimated as being probably 

 from fifty to sixty feet, and from the close resemblance of its 

 teeth to those of the living Iguanas, there is little doubt that 

 it was herbivorous and not carnivorous. The femur of a large 

 Iguanodon measures from four to five feet in length, with a cir- 

 cumference of twenty-two inches in its smallest part. From 

 the disproportionately small size of the fore-limbs, and from the 

 occurence of pairs of gigantic three-toed footsteps in the same 

 beds, it has been concluded, with much probability, that Igu- 

 anodon, in spite of its enormous bulk, must have walked tem- 

 porarily or permanently upon its hind-legs, thus coming to pre- 

 sent a most marked and striking affinity to the Birds. 



