OSTEOLOGY OF PTERANODON. 



BY GEORGE F. EATON. 



(with PLATES I— XXXI.) 



The collection of North American Cretaceous pterodactyls assembled by Professor 

 Marsh at the Peabody Museum of Yale University is numerically very large, consisting 

 of the remains of 465 individuals of Pteranodon as well as seven individuals of the 

 allied genus Nyctosaurus, these two genera from the Niobrara Cretaceous of western 

 Kansas being originally placed by Marsh in the order Pteranodontia. For various rea- 

 sons it has seemed wise to limit the present memoir to the treatment of Pteranodon, 

 postponing until a more opportune time the discussion of a few additional facts regard- 

 ing the structure and affinities of Nyctosaurus. Of the great number of examples referred 

 to Pteranodon, a few are complete enough to show new generic characters, but the 

 majority of individuals are so incomplete and fragmentary as to be of comparatively 

 little value. Owing to this condition of the material, it has been found inadvisable to 

 treat each species separately, and the present memoir has been accordingly divided into 

 topics based on the principal skeletal parts. As with one exception the specific names 

 have remained unchanged, an elaborate synonymy is obviated, the only species here 

 recognized that has been known under another name being Pteranodon occidentalism which 

 was first described by Professor Marsh as Pterodactylus Oiveni {Am. Jour. Sci., June, 1871). 



As might be expected, in carrying on the work done by Professor Marsh on this 

 group, considerable difficulty was met with at the outset because of the incomplete and 

 fragmentary condition of much of the material first obtained, and from which the types 

 of the species of Pteranodon were necessarily chosen. With this fact in view, it need 

 occasion no surprise that of the three individual specimens originally referred to Pteran- 

 odon occidentalism only one, No. 1164, 1 is complete enough to be of any value in the 

 present work. This specimen consists of a right humerus peculiarly crushed, three 

 carpals, and the first and fourth phalanges of the wing finger, together with a few barely 

 recognizable fragments presumably belonging to the same wing. Later Professor Marsh 

 observed the form of the jaws of P. occidentalis in a fragmentary skull, No. 1179, and 

 from his notes it is evident that he considered this specimen also a type of the species. 



P. ingens, the second species described by Marsh, was based upon much more satis- 

 factory material. One of the types, No. 1175, is a magnificent but incomplete skeleton, 

 which does not include the fifth digit of the hand, the so-called wing finger. Another 

 valuable type of this species is the large nearly complete skull, No. 2594, to be partic- 

 ularly described in the following pages. The other types of P. ingens consist only of 

 a few poor fragments of wing bones, adding nothing to the characters shown by No. 1175 

 and No. 2594. 



When Professor Marsh separated P. ingens from P. occidentalism the skull of neither 

 species was known to him. With the exception of the carpals, the humerus was the 



1 The numbers used in the present memoir refer to the Paleontological Catalogue of the Peabody 

 Museum of Yale University. 



