Fossil Birds in the Marsh Collection of Yale University 9 



Baptornis advenus Marsh. 



{Plate I, Figs. 1-6; Plate II, Fig. 12.) 



Marsh, Amer, Joum. Sci., ser. 3, XIV, 1877, 86. 



Holotype. Cat. No. 1465, Peabody Museum, Yale University. Wallace Co., 

 Kansas. Cretaceous (Niobrara). G. P. Cooper, collector. 



The discovery of this fossil (two fragments) or fossils, of which there 

 is no question about their having belonged to the skeleton of a new 

 extinct bird, led Professor Marsh to believe that the species to which 

 it belonged in life was "a small swimming bird cotemporary with 

 Hesperornis," and that what he has before him was "a perfect tarso- 

 metatarsus bone from the same geological horizon." He further 

 maintained in his article that "This specimen, although pertaining 

 to a bird not fully adult, is in excellent preservation, and so charac- 

 teristic that it may be readily distinguished from any forms already 

 described." This statement, in some particulars, is sustained by the 

 figures I here present in Plates I and II (Figs. 1-6, 12), which are some- 

 what reduced in size and present the two fragments from three points 

 of view. Now I am not informed as to the nature of the proof Profes- 

 sor Marsh may have had, going to show that these two pieces belonged 

 to the same individual. The fracture surfaces, when approximated, 

 do not indicate that they did, for they do not join in the way they 

 would had the shaft of the bone been simply broken across. Possibly 

 as much as the middle third is missing — that is, if the specimen is 

 from the same individual, which I am inclined to doubt, inasmuch as 

 the proximal fragment is from a subadult bird (PI. I, Figs. 2, 5, 6), 

 as Professor Marsh states, while the distal fragment presents no 

 evidence of such having been the case. 



"In general shape and proportions," continues Professor Marsh, 

 "this bone most nearly resembles the corresponding part in Hesper- 

 ornis, but differs from it decidedly in the outer metatarsal, which at 

 its lower end scarcely equals the adjoining one in size and length. 



" In Hesperornis, on the contrary, the outer metatarsal is more than 

 double the size of the third. 



"In the present specimen the three trochlear articulations of the 

 distal ends are nearly equal. 



"The existence of a hallux is indicated by a small elongated depres- 

 sion on the inner metatarsal, a short distance above the articulation. 



"As in Hesperornis, there are no canals or grooves for tendons on 

 the posterior face of the proximal end." 



