FOKT UNION OF CRAZY MOUNTAIN FIELD, MONT. H 



collection, and the few specimens from the Silberling Quarry, in the 

 American Museum are not yet studied and do not enter into this 

 study. For the most part they duplicate the collection described 

 here. 



Of other mammal discoveries in the Fort Union, the first of any im- 

 portance was made by J. F. Lobdell in 1926 in a coal mine at Bear 

 Creek, Mont. Collections were later made here for the Carnegie 

 Museum and the American Museum and have been described by me 

 (Simpson, 1928a, 1929a, b). The small but interesting fauna is of 

 Upper Paleocene age, about equivalent to the Tiffany. 



Discoveries in northern Wyoming, west of the Bighoi-n Mountains, 

 have been of outstanding value. Sinclair and Granger (1911, 1912; 

 also Granger, 1914) had found a fauna of Paleocene aspect here in 

 beds which had previously been considered to be true Eocene and 

 which they named Clark Fork. In 1927-29, Dr. G. L. Jepsen, work- 

 ing for Princeton University, found three distinct faunal horizons in 

 (nominal) Fort Union strata beneath the Clark Fork in this area. 

 He has shown that these correspond in age to the Puerco, Torrejon, 

 and Tiffany, and hence has for the first time established a definite 

 sequence of four distinguishable Paleocene mammahan faunas in a 

 single continuous stratigraphic section (Jepsen, 1930). The faunas 

 so far described are small but typical. Subsequent collecting under 

 Jepsen at the same localities has yielded much more and better 

 material, but the results have not yet been published. 



Sporadic discoveries of one or two specimens have been made at a 

 few other Fort Union localities, but none is of much importance. 

 The type of Titanoides immaevus came from near the type locality of 

 the group, Buford, N. Dak. (Gidley, 1917). Typically Middle 

 Paleocene forms, Tetraclaenodon and Pantolamhda, were found in 

 Billings County, N. Dak. (Lloyd and Hares, 1915). In Fort Union 

 or Kingsbury beds of the Bighorns a jaw identified by Gidley as 

 Tricentes was found (Stanton, 1909, p. 268). Eocene fossils were 

 found in supposed Fort Union beds in the Powder Eiver Basin (Wege- 

 mann, 1917). The last-mentioned fossils, and perhaps that from the 

 Kingsbury, are not really from the Paleocene, or from true Fort 

 Union. 



The Paskapoo of Alberta, which may be considered in a general 

 way a northern extension or equivalent of at least the upper part of 

 the Fort Union, has yielded a few mammals, the first found by Brown 

 in 1910 (Simpson, 1927), with later discoveries mostly by Russell 

 (1926, 1929, 1932), all extremely fragmentary. Recently Patterson, 

 working for the Field Museum of Natural History, collected fine' skele- 

 tons of Barylambda, an ally of Titanoides, at an Upper Paleocene level 

 in the Plateau Valley formation of western Colorado (Patterson, 1933, 

 1934, 1935, 1937). 



