158 TEN YEARS^ PROGRESS IX VERTEBRATE PALEONTOLOGY 



is inexact or doubtful in most cases. The vertebrae, limb and foot bones 

 of Arsinoifherium, vertebrae and limb bones of MoBntherium, Palceomas- 

 todon, and Ancodon, limb bones of Apterodon and Pterodon have been 

 identified with reasonable certainty. The remaining land mammals are 

 known only from skulls and jaws (except Barytherium, jaws and parts 

 of limbs). 



The results so far obtained are due in the first place to the work of the 

 Eg3^ptian Geological Survey and the British Museum; the American Mu- 

 seum of Natural History and the Stuttgart Museum have since secured 

 fine collections. The earlier collections were described by Doctor Andrews 

 in 1906; the Stuttgart and American Museum collections have not yet 

 been fully described, but are partly known from preliminary notices. 



In considering the affinities of this fauna it is well to remember that 

 Egypt is today zoologically a part of the Holarctic, not of the Ethiopian 

 region. Its fauna includes a minorit}^ of Ethiopian genera, but is mostly 

 related to that of southern Europe and western Asia. But in the early 

 Tertiary the eastward extension of the Mediterranean separated Africa 

 more or less completely from the northern world, while the Saharan 

 desert was probably not an eeffctive barrier as it is today. Egypt was 

 then part of an isolated Ethiopic continent, with possible Asiatic but no 

 European connection during the early Tertiary. So much is certain 

 from the known extent of marine formations of that period. 



Immigrant Group 



Eeviewing the fauna more in detail, the inmiigrant group includes 

 three orders of mammals, each represented by one family. The Carnivora 

 all belong to the Creodont family H3'£enodontidae. Xo modernized (Fissi- 

 pede) carnivora are present, although these had already appeared in the 

 European and North i^merican Upper Eocene. The Hyaenodont genera 

 are all Holarctic except one, which has not been found in the north, al- 

 though perhaps merely from lack of evidence. But the species are very 

 distinct, and unfamiliar in adaptive t3rpe; one would conclude that the 

 Hyaenodonts, invading a new field where they were not in competition 

 with other families of carnivora, were expanding and modifying into new 

 adaptations. 



The Artiodactyla include also but one family, the Anthracotheres, and 

 of these only one conmion genus, Ancodon, with two or three species, 

 allied to Upper Eocene and especially to early Oligocene species of 

 Europe. This geniis is not found in North America until the Lower 

 Oligocene. 



