FORT UNIOlSr OF CRAZY MOUNTAIN" FIELD, MONT. 63 



part arboreal in habitus. The primates, also, may well have been 

 mainly or entirely arboreal. The creodonts were probably mainly 

 terrestrial, but it is probable that some of them were at least semi- 

 arboreal. The abundant hyopsodontids were probably, judged from 

 Torrejon and later allies, more unguiculate than ungulate in general 

 habitus, and the smaller forms may well have been arboreal. The less 

 common larger condylarths and the very rare pantodonts were prob- 

 ably terrestrial. The evidence is not at all conclusive, but it warrants 

 the tentative conclusion that this fauna is largely arboreal, which is well 

 in accord with the evidence that the quarries were in a swampy and 

 heavily forested area and would go far toward explaining the unusual 

 facies of the quarry faunas. There is, indeed, a decidedly fossorial 

 humerus (of imknown association with teeth) in the collection; the 

 facies association of arboreal and fossorial animals is not uncommon 

 and is in accord with a forest environment. 



The ordinal composition of the Scarritt Quarry collection differs 

 significantly from that of the Gidley Quarry only in the almost com- 

 plete absence of carnivores. Within the other orders, the family com- 

 position is as nearly similar as would be expected in deposits of similar 

 facies but different ages except among the Primates. The abundant 

 Gidley Quarry types, Paromomys and its closer allies, are not repre- 

 sented in the Scarritt Quarry collection, and instead of them the more 

 specialized, perhaps more strictly frugivorous, plesiadapids and car- 

 poles tids have become fairly common, although the first were un- 

 common and the latter very rare in the Gidley Quarry. 



The Gidley Quarry is also interesting from the unusual occurrence 

 of its fossils and the indications of the possible conditions surrounding 

 death and burial of its animals. The remains are invariably frag- 

 mentary, and with extremely rare exceptions there is no association 

 of specimens. The bones seldom show any signs of weathering or 

 rolling but are usually fractured, and even when they abut against 

 wholly undisturbed matrix these fractures are clean, fresh breaks. 

 Some further fracturing and dissociation have resulted from the com- 

 pacting of the bed and development of slip planes, but for the most part 

 these preceded fossilization. Most of the jaws have lost some teeth 

 before burial, and many have lost all the teeth. These isolated teeth 

 (clearly lost after death but before burial) are common ia the collection. 

 There are many bone fragments, but it is clear that the quantity of 

 skeletal material present, even in the most fragmentary state, cannot 

 by any means represent all the bones of the animals represented by 

 their jaws and teeth. 



The rather abundant presence of fish remains, often in articulation, 

 and of aquatic reptile fragments and the presence of aquatic mollusks 

 (rare in this quarry, but present), together with the nature of the sedi- 

 ments, suggest that the deposit was formed in sluggish water, perhaps a 



