200 THE AGE OF MAMMALS 



first evidence of the existence of extinct land animals in this region, and 

 in 1901-1905 explorations under Beadnell and Andrews of the Egyptian 

 Survey and British Museum resulted in a series of remarkable discoveries, 

 which were ably set forth in Andrews' fine memoir of 1906.' 



Supplementary explorations l)y the author, and Mr. Granger of the 

 American Museum,^ in 1907, and l)y other institutions, promise to round 

 out our knowledge of this newly found world of African life in early- 

 Tertiary times. 



As shown in the accompanying section, the bluffs are sixteen hundred 

 feet in thickness. The lower level, or 'Zeuglodon Zone' (200 feet) is a 

 purely marine formation rich in remains of the primitive Eocene Cetacea 

 (Zeuglodon and Prozeuglodon) . Above these (500 feet) are marine and 

 estuarine beds in which remains of Zeuglodon are mingled with those of 

 fluviatile and shore-living mammals, including sea-cows (Eosiren), am- 

 phibious animals (Moeritherium) related to the proboscidean stock, and 

 still larger quadrupeds (Barytherium) of unknown affinity; this may be 

 termed the 'Barytherium Zone' and is believed to be of Upper Eocene age 

 from evidence afforded partly by the animals, partly by richly fossiliferous 

 shell layers. Above this are fluvio-marine beds (900 feet), designated as 

 the ' Arsinoitherium Zone,' which yield a splendid representation of the 

 land fauna of northern Africa in Lower Oligocene times. Beside the mammals 

 we here discover giant land tortoises (Testudo amnion) resembling those of 

 modern Madagascar, giant pythons (Gigantophis) , ostrich-like birds (Ere- 

 mopezus), broad-snouted crocodiles (Crocodilus megarhinus) similar to 

 those now found in African rivers, as well as the slender-snouted gavial- 

 like forms (Tomistoma) similar to those now found in Borneo. In the 

 rivers beside the numerous sirenians and zeuglodont-whales there swam 

 river turtles (Podocnemis) related to those found to-day only in South 

 America; there were also large sea snakes {Pterosphenus) , and in the Mediter- 

 ranean Sea near by were found great floating leather-back turtles {Thalas- 

 sochelys) closely similar to modern forms. 



So far as the mammals mirror their surroundings. Eocene Libya was a 

 savannah country, partly open, partly thicketed or jungled, partly forested, 

 of about the same temperature as to-day, fairly well watered, and subject 

 to occasional freshets and floodings from sand-bearing rivers to the south. 

 These old river beds of loosely compacted sand have yielded the greater 

 part of the thousands of isolated specimens which have been taken from 

 this region, including forty-five species of mammals, twenty-one of reptiles, 

 and twenty-three species of fishes. 



The fauna as a whole shows affinities to that of the modern life of 



* Andrews, C. W., A Descriptive Catalogue of the Tertiary Vertebrata of the Fayum, 

 Egypt. 4to, London, 1906. 



^ Osborn, H. F., Hunting the Ancestral Elephant in the Fayum Desert. Century Maga- 

 zine, Vol. LXXIV, no. 6, October, 1907, pp. 815-835. 



