BIRDS OF THE PAST WETMOBE 383 



the forms found are more like modern types, so that the greater 

 number of the approximately 25 species of fossil birds that have 

 been described from the Eocene of North America are now placed in 

 modern families. It may be said that a number of these have been 

 named from very inadequate material and that some, perhaps, may 

 not be birds, as the bones from which they have been described are 

 so fragmentary as to make it difficult to decide whether they belong 

 in the Class Aves or elsewhere among the vertebrates. Others on 

 further study may be found sufficiently peculiar to warrant their 

 separation as distinct from living families. 



Diatrifina steini from the lower Eocene (Lower Wasatch) of 

 Wyoming is one of the few fossil birds found that is represented 

 by a nearly complete skeleton (see pis. 6 and 7). This great bird 

 stood nearly 7 feet in height and was developed for a terrestrial life. 

 It possessed strong legs, and a heavy head, with a great arched bill, 

 and very small, almost aborted wings. Superficially it suggests the 

 remarkable Pkororhacos of Patagonia, and probably was similar in 

 habit. It has been described fully by Matthew and Granger but has 

 not been carefully studied, so that its exact affinities are not certainly 

 known. It is placed at present near the cranes and rails, but does 

 not seem to have very close affinity with either. 



Another form that is known from a nearly complete skeleton is 

 GaJlvnuloides wyoTiungensis from the middle Eocene (Green River) 

 of Wyoming, a gallinaceous form, typical of a special family re- 

 lated to the curassows and guans, fowl-like birds that live among 

 the branches of trees. Minerva saurodosis of the same age is appar- 

 ently a primitive owl, while Preshyomis is a shore bird placed in a 

 separate family from any of our modern species. It seems to have 

 resembled an avocet but probably was more aquatic and swam more 

 readily. Nautilornis was an auklike form that differs from modern 

 auks in that it seems adapted for wading as well as for swimming. 

 Other species that have been described from this age are so frag- 

 mentary as to be uncertain in character. 



Bird remains from the Oligocene of North America are as yet few, 

 so that to date only six species have been recorded. Two of these, 

 a cormorant, and a supposed pheasant named by Shufeldt, are of 

 uncertain status. The only important deposit of this age that has 

 yielded much bird material to the present is one in Weld County, 

 Colo., where collectors from the Colorado Museum of Natural His- 

 tory in Denver, in exhuming great series of such strange mammals 

 as Trigonias^ Symborodon^ and Archaeotherium^ have uncovered a 

 few bones of birds. From these the writer has recently described 

 four species representing peculiar genera not known in modern times. 

 Phasmagyps patrltus is a vulture related to the living black vulture 

 but about one-half larger. Palaeogyps prodromus^ in the same family 



