212 W. D. Matthew — Fossil Vertebrates and 



Characteristics of Paleocene Mammal Faunas. 



The principal Paleocene mammals in order of their 

 importance, abundance and variety are : 



1. Taligrada, two families, Periptychidse and Panto- 

 lambdidse; limited to the Paleocene. 



2. Gondylarthraj two families, Mioclsenidse and Phena- 

 codontidae, the first limited to the Paleocene, the second 

 surviving into Lower Eocene. 



3. Carnivoray of the very primitive creodont families, 

 Oxyclsenidse, Arctocyonidas and Mesonychidae, the first two 

 surviving as rarities into the Lower Eocene, the last 

 found throughout the Eocene. But the progressive 

 Miacidae also have a representative in the Torrejon. 



4. TcBfiiodonta, peculiar archaic types allied to the 

 edentates. Two families, Stylinodontidae and Conoryc- 

 tidge, only the former surviving into the Eocene, as a 

 rarity. 



5. Multituberculata are fairly common and repre- 

 sented by several genera allied to the Lance and Belly 

 River Plagiaulacidae. They give a distinctly Mesozoic 

 aspect to the fauna. A single specimen of a multi- 

 tuberculate has been found in the lower Wasatch of 

 Wyoming. 



6. Insectivora. Besides the Leptictidae, which survive 

 until the Oligocene, there are some genera of more uncer- 

 tain affinities : Mixodectidae peculiar to the Torrejon, 

 Pentacodon supposed to be related to the Eocene Panto- 

 lestidae, and an interesting Zalambdodont genus Palce- 

 oryctes. 



7. Marsupials. The true opossums appear in the 

 Puerco, taking the place of the nearly related but more 

 archaic Cimolestidae of the Judith and Lance. They last 

 through to the present time, though always rare fossils. 



At the close of the Paleocene, in the Tiffany and Cer- 

 naysian and especially in the Clark Fork, an increasing 

 number of Eocene mammal groups are represented. The 

 Plesiadapidae of the Tiffany, Cernaysian, Clark Fork and 

 Eocene are on the border between menotyphlan insect- 

 ivores and Primates, and in the Tiffany the earliest 

 true primate appears, a tar slid (^^anaptomorphid'O- 

 Two primitive members of the Eocene oxyaenid family 

 and the Lower Eocene genus Coryphodon are found in the 

 Clark Fork horizon. These few precursors, however, 



