Article XL — EVOLUTION OF THE AMBLYPODA. 

 PART I. TALIGRADA AND PANTODONTA. 



By Henry Fairfield Osborn. 

 Twenty-nine Text Figures. 



The Amblypoda constitute a sharply distinguished order of 

 Ungulates which probably sprang from the Creodonta during the 

 Cretaceous period and extended through the Eocene period in 

 three great stages of evolution known as the suborders Taligrada, 

 Pantodonta and Dinocerata, the latter entirely confined to North 

 America. 



They are arrested or persistently archaic in structure through- 

 out, but especially in the brain, the triangular teeth, and the penta- 

 dactyl feet. The morphological problems involved in the skeleton 

 and teeth, and the phylogenetic problems involved in the suc- 

 cession and extinction of the main and collateral lines, form the 

 main subjects of this essay. 



The American Museum has sent out a series of expeditions 

 after remains of the Amblypoda : First, into the Wasatch of 

 Wyoming, 1891 ; second, into the Bridger and Washakie Basins, 

 1893 and 1895 ; third, into the Torrejon, 1892 and 1896; 

 fourth, into the Wasatch of New Mexico, and Big Plorn Moun- 

 tains of Wyoming, 1896. We have thus succeeded in bringing 

 together invaluable material for the history of this remarkable 

 group from the time it issued in the Creodont-like Pa/i/olambda, 

 of the Torrejon Beds until it became extinct in the largest 

 Uintatheres of the Upper Washakie and Middle Uinta Beds. 



Several very important results are obtained : 



First. — The evidence can be clearly stated as to the succession 

 of the known types of Pantolambdid^e, Coryphodontidae and 

 Uintatheridas. Many prophetic or ordinal characters are now 

 observed in the earliest types ; certain species of Coryphodo?i are 

 found to show the rudimentary parietal horns and the incisiform 



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