232 PALEONTOLOGY: H. F. OSBORN Proc. N. A. S. 
An elephant stock, adapted to grassy plains, savannas, and steppes, of wide migration. 
These primary stocks gave off from two to six branches each, so that 
the Proboscidea as a whole are not two branched (i.e., mastodonts and 
elephants), as formerly supposed, but many branched or polyphyletic. 
The forest and savanna browsers and the grazers of the plains and steppes 
were the long distance travelers and from an African or Asiatic center 
in Eocene times they reached in the Middle and Upper Miocene all the 
continents of the world except Australia, while the amphibious forms 
remained in Africa and southern Eurasia. Certain of these branches, 
like the true mastodons, are of very great geologic antiquity. Intelligent, 
independent, well defended, resourceful, adaptive, we find eleven very 
distinct branches of proboscideans persisting into Upper Pliocene times, 
five of the least hardy of which became extinct during the colder condi- 
tions of the Lower Pleistocene. 
The known lines of evolution are shaded on the accompanying diagram ; 
the unknown are left in white. The adaptive radiation may be expressed 
in a formal classification as follows: 
Amphibious and swamp-living stock 
I. MOERITHBRIOIDEA (Moeritheres) 
1. Moeritheriini, 2 amphibious or swamp-living forms known in the Upper 
Oligocene of Africa. 
II. DINOTHERIOIDEA (Dinotheres) 
2. Dinotheriini, 3 large amphibious forms frequenting the rivers of southern 
Eurasia throughout the Miocene to the close of the 
Pliocene. 
Forest and savanna grazers 
III. MASTODONTOIDEA (Mastodonts and Bunomastodonts) 
mastodonTidae OR "true mastodonts," including the subfamily 
3. Mastodontinae, springing from Palceomastodon of the Oligocene of North 
Africa, and terminating with Mastodon americanus 
of the Pleistocene forests of North America; grinders 
lophodont, lacking trefoils. 
4. Serridentinae, 4 first known in the Middle Miocene of France and Switzer- 
land, spreading over into India and North America; 
lacking the trefoils. 
bunomastodontidae, the bunomastodonts, springing from forms similar to the 
Phiomia of North Africa and separating into four 
main divisions : 
5. Notorostrinae, a special branch entering the Andean region of South America 
and spreading over the South American continent, 
distinguished by the loss of the lower tusks and the 
abbreviation of the jaw. 
6. Longirostrinse, typical long-jawed bunomastodonts arising in North Africa 
{Phiomia), spreading all over southern Europe, Asia, 
and North America, and giving off: 
7. Rhynchorostrinae, beaked bunomastodonts, known only in the southern 
United States and northern Mexico, with powerful 
downturned upper and lower tusks. 
I 
