FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 269 



Order Pantodonta: A group of middle-sized to large, very archaic ungulates (or 

 "subungulates"). The dentition is little or not reduced in number, and 

 remains practically brachj'odont, but exhibits a high degree of lophiodonty 

 even in the earliest members. The primitive pattern is strongly selenodont 

 but this is secondarily masked to some extent in later forms. The canines 

 are apparently always large, and may develop into great tusks. Skull and 

 jaws are generally massive with verj^ powerful muscle attacliments. The 

 brain remains very small and primitive. The limbs are massive and strong, 

 ambulatory to graviportal, and retain many primitive features such as 

 separate radius and ulna, tibia and fibula, and five toes on each foot. 

 Carpus and tarsus retain and strongly accentuate the alternating arrange- 

 ment. 

 Family Pantolambdidae: Relatively less advanced forms, with the teeth 

 fully selenodont, the skull roof little or not flattened, the tail long 

 and heavy, and other primitive characters. 

 Subfamily Pantolambdinae: Lighter, more ambulatory types of smaller 

 size and with astragalus still retaining some condylarth characters. 

 Middle Paleocene. North America. 

 Subfamily Barylambdinae: Heavy graviportal types of larger size, with 

 fuU}^ specialized pantodont type of astragalus. Upper Paleocene. 

 North America. 

 Family Coryphodontidae: Highly specialized forms, large in size, all with 

 graviportal limbs, teeth with primitive crescents considerably modified, 

 skull roof broad and flat, tail reduced. Upper Paleocene — lower Eocene 

 in North America. Lower Eocene in Europe. Upper Eocene to Middle 

 Oligocene in Mongolia. 

 Family Pantolambdodontidae: A somewhat dubious group known from 

 lower jaws only, which suggest relationship with Pantolambda but have 

 numerous differences in details. Upper Eocene. Mongolia. 



The present fauna contains few remains of pantodonts, but Panto- 

 lambda is represented by various fragmentary specimens, some of 

 wliich indicate a species first defined, and at present known only, from 

 this fauna. ^^ 



Family PANTOLAMBDIDAE Cope, 1853 



Genus PANTOLAMBDA Cope, 1883 



Douglass (1902b, p. 224) described and figured an upper premolar 

 perhaps of this genus. It is about the size of P^ of P. bathmodon, but 

 differs somewhat in form, the main cusp being more central and the 

 external margin less sharply notched. The National Museum ma- 

 terials does not serve to define this form. The second Pantolambda 

 mentioned by Douglass (1908, p. 24) probably belongs to the species 

 defined below. 



28 The present conception of the Pantodonta, especially as regards its essential unity as here defined, 

 owes much to Patterson's discovery of complete skeletons oi Baryla mbda and to his fine studies of them (Pat- 

 terson, 1933, 1934, 1935, 1937). Although not from the Crazy Mountain Field, the type species and specimen 

 of Titanoide!^ was found in the Fort Union and named and described by Gidley (1917), and it was originally 

 proposed to include a discussion of it in this work, but Patterson's studies make this quite unnecessary. 



