THE NIOBRARA GROUP. 3 



One peculiarity of the order is found in the quadrate bones, which not only- 

 places him in the rank of reptiles, but enables the student to distinguish from it 

 the different species. In shape this bone resembles the external ear of a man, 

 and is composed of the bones that help make up the internal ear in mammals. 

 This bone connects the under jaw with the skull and allows all the motion nec- 

 essary. His tongue was long and forked, like a serpent's, and was thrust out 

 while in motion. The only noise he could make was a hissing sound. While at 

 rest, "the tongue was concealed in a sack under the windpipe." Leiodon proriger 

 Cope, reached a length of eighty feet; it had a long slender neck, twenty feet in 

 length ; the tail was long and powerful, and was doubtless used both as a rudder 

 and propeller. Clidastes tortor was an elegant creature, about forty feet in length ; 

 its vertebral column was provided with an additional set of articulations, so as to 

 enable it to coil itself like a snake ; this seems to be its favorite position, as I 

 have often found it thus coiled. 



Clidastes pumilus. Marsh, was a little creature, ten or fifteen feet long, and 

 doubtless often fell a victim to the larger saurians or rapacious fishes with which 

 the cretaceous seas abounded. The Pterodactyls of the Niobrara differed very 

 much from those of Europe ; they were much larger ; I have found them with 

 an expanse of wing of twenty-five feet: they were also without teeth, and Marsh 

 has made the new genus Pterodon for them. One peculiarity of the Niobrara 

 group is the presence of the only known birds armed with teeth. 



Idhyornis dispar, Marsh, was a bird six feet in height ; it was armed with 

 long sharp te eth ; the wings were poorly developed; they were swimmers and 

 lived on fishes. Other birds are found no larger than a dove ; they are ar- 

 ranged in families according to the position of the teeth, which are placed either 

 in grooves or sockets. Believers in the evolution theory have received the dis- 

 coveries of reptile-like birds as a positive proof that they have descended from 

 reptiles. Of all the strange animal forms found in the rich fossiliferous beds of 

 western Kansas, I think Cope's Frotostega gigas, or marine tortoise, is the most 

 unique. Cope calls them the boatmen of the cretaceous ocean. 



In 1877 I discovered a specimen that measured twenty feet from one flipper 

 to the other; the distance between the condyles of the lower jaws was eighteen 

 inches. We know that in modern turtles the young, when first hatched, have 

 free ribs like other animals, and that in process of growth, bone is deposited in 

 the skin, the ribs expand and unite in connection with the breastbone, forming a 

 perfect shell, or house. This is not the case in Frotostega; in the adult the riHs 

 are free, and, in place of a shell, these animals are provided with great dermal 

 plates, two feet in diameter, an inch thick in the center and beveled off to a thin 

 figured margin. When Prof. Cope discovered this animal, he was confident he 

 had found a young turtle, but it was impossible to believe that an animal measur- 

 ing twenty feet from flipper to flipper had just been hatched, and on studying the 

 bones he was forced to conclude that it was a full grown animal, and to be one of 

 those miniature types that is often found in the geological strata — another fact 

 taken by many to prove that animals of the present day have been derived from 



