Trof. 0. C. Marsh — Wew Cretaceous Pterodactyls. 345 



IV. — Pkincipal Characters of American Cretaceous 

 Pterodactyls. 



Part I. The Skull of Pteranodon.^ 



By Professor 0. C. Marsh, M.A., F.G.S., 

 of Yale College, Newhaven, Conn., U.S. A, 



THE first remains of Pterodactyls discovered in this country- 

 were found by the writer, in the autumn of 1870, near the 

 Smoky Hill River, in Western Kansas. These belonged to a 

 gigantic species, which was described by the writer in 1871, and is 

 now known as Pteranodon occidentalis. The geological horizon of 

 these fossils was in the Middle Cretaceous, in the same deposits that 

 contain the Odontornithes, or Birds with teeth. In the following 

 year, additional specimens were secured by the writer in the same 

 region, and referred to two new species of the same genus.^ 



In 1872, the writer again visited this region, and made a careful 

 search for other specimens, and for several subsequent years had 

 parties exploring the same deposits systematically, with good 

 results ; so that at the present time the remains of more than six 

 hundred individuals of these reptiles have been secured from this 

 horizon, and are now in the museum of Yale College. 



The most of these remains represent gigantic species, the largest 

 having a spread of wings of nearlj^, or quite, twenty-five feet. 

 These all belong to the genus Pteranodon, and pertain to five species. 

 One species referred to this genus was comparatively small, having 

 a spread of wings of not more than three feet. A few specimens 

 were found, intermediate in size, and these represent the genus 

 Nyctodactylus, of which only a single species is known. 



All these Cretaceous Pterodactyls, so far as known, differ widely 

 from the members of this group in the old world, especially in the 

 absence of teeth, and hence have been placed by the writer in a new 

 order, the Pteranodontia, from the typical genus, Pteranodon.^ 

 Other important characters of this order have since been made 

 known by the writer, showing that these strange reptiles constitute 

 a well-marked group, much more specialized than any hitherto 

 discovered. 



In the present paper, the skull of one species of Pteranodon is 

 described and figured as typical of the order, and the remaining 

 part of the skeleton will be discussed in subsequent communications. 



The Skull. — The skull in the genus Pteranodon is very large, and 

 much elongated. The facial portion is greatly produced forwards, 

 and an enormous sagittal crest extends far backward, and somewhat 



1 From the American Journal of Science, vol. xxvii. May, 1884. 



2 op. cit. vol. i, p. 472, June, 1871; vol. iii. p. 241, April, 1872, and p. 374, 

 May, 1872. 



3 op. cit. p. 507. vol. xi. June, 1876 ; p. 479, vol. xii. Dec. 1876, and vol. xxi. 

 p. 342, April, 1881. See also vol. xsiii. p. 251, April, 1882. 



