CENOZOIC ERA: AGE OF MAMMALS 623 



the line led to the human race and from the other to the living anthro- 

 poids, namely the chimpanzee, orang, gibbon, and gorilla cannot be 

 certainly determined. " (Osborn.) The discussion of the so-called 

 man-ape (Pithecanthropus) and others will be taken up in connection 

 with the evolution of man in the next period. 



REFERENCES FOR PRIMATES 



Beddard, F. E., — Mammalia. 



Woodward, A. S., — Vertebrate Paleontology, pp. 403-410. 



Birds. — The presence of birds in the Lower Eocene, typically 

 modern in structure and in no sense intermediate between the Meso- 

 zoic toothed birds with vertebrated tails and the birds of to-day, 

 makes the question as to the origin of the typical Tertiary life (birds 

 and mammals) exceptionally difficult in the present state of our 

 knowledge. (The discussion under Rise of Mammals, p. 590, should 

 be considered in this connection.) 



Although few of the birds of the Eocene can be referred to living 

 genera, they are modern in all essential features. Even at this early 

 date there were living relatives of the vultures, storks, secretary birds, 

 sandpipers, Old World quail, sand grouse, cuckoos, swifts, herons, 

 and pelicans. The appearance of a great, flightless bird (Gastornis) 

 as large as an ostrich but apparently unrelated, presenting affinities 

 to wading and aquatic birds, is interesting as showing the advanced 

 stage of evolution at this early time. 



The bird life of the Eocene of Europe (Quercy, France) gives a 

 clue to the climate and environment of portions, at least, of Europe 

 at that time, since it was fitted to inhabit great, warm plains, scattered 

 over with groves. The assemblage is a tropical one and approaches 

 that now found in tropical Africa and South America, although, as 

 in the case of the vegetation (p. 634), tropical forms are associated 

 with others that are now typical of temperate regions. 



Most of the bird fossils are from the Miocene and later formations, 

 and belong to existing families and often to existing genera. A 

 remarkable bird (Phororhachos) from the Miocene deposits of 

 Patagonia shows the extreme to which bird evolution may be carried. 

 It stood about seven feet high and had a head as long as that of a 

 horse, armed with a pick-like projection. Its habits have been 

 variously conjectured. The loss of wings indicates a semiarid 

 condition. 



CLELAND GEOL. — 40 



