382 AV. D. MATTHEW THE CRETACEOUS-TERTIARY PROBLEM 



The tenii Paleoceiie, eiiriont in Europe,^ has hardly come into use in 

 thit; country. As applied here it denotes what we have heen calling Basal 

 Eocene, comprising the Fort Union, Puerco and Torrejon, and other 

 equivalent formations older than the Wasatch or typical Lower Eocene. 

 The rea.sons will appear later for its acceptance as an epoch distinct from 

 the Eocene. 



The typical and best known Paleocene fauna is that of the Puerco and 

 Torrejon fonnati<ms, T^acimiento terrane, of Xew Mexico. The strati- 

 graphic relations of the faunie of the four fossiliferous levels of this ter- 

 rane have been explained by Doctor Sinclair. There is no marked strati- 

 graphic break in the t^rrane. but there are two distinct faunae, no species 

 surviving from one to the other. Some of the genera and most of the 

 families pass through, represented in the later horizon by distinct species 

 or genera, usually more progressive. In their broader aspects the two 

 faunae have much in common to distinguish them from those of earlier 

 or later age. 



The Fort Union (not including the Lance) is provisionally correlated 

 with the Nacimiento terrane. In its npper part is found a mammalian 

 fauna composed in part of species identified with Torrejon species, but 

 the rest of this fauna is not comparable with anything in^ either Puerco 

 or Torrejon. A small flora from the Puerco is identified by Doctor 

 Knowlton as indicating "Denver or perhaps as late as Fort Union" age. 

 The diverse element of the Fort Union fauna is best interpreted as indi- 

 cating a somewhat different environmental facies, somewhat more of a 

 swampy delta and less of a floodplain type of deposit l)eing indicated by 

 the lithologic features. 



Characters of the Paleocexe Vertebrate Faunas 



(1) The mammals are dominantly Placentals of archaic orders. A 

 minority are Multituberculates, related (anct. Broom) ^ to the existing 

 Monotremes. Approximately 10 per cent of the faniui is Multitubercu- 

 late. The remainder belong to groups of placentals which became extinct 

 during the Eocene. The later Tertiary and modern orders of mammals 

 are not present except the Camivora and certain groups donbtfully re- 

 ferred to Tnsectivora and Edentates. There are no Perissodactyls, Artio- 

 dactvls, Podents, or Primates, tliese orders appearing suddenly at the 

 beginning of the true Eocene. 



"But not always with the sl^nifirancp hore piven to it. Sonip authors includo in it 

 the Ivondon Clay, equivalent to our Wasatch or Ix)wer Eocene. 



« I do not indorse this view. New evidence bearing on it will shortly be published by 

 Mr. Granger. 



