ART. 1. PRIMATES OF THE FORT UNION GIDLEY. 23 



by certain authorities, that some members of the Eocene Tarsiids 

 could have given rise to any part of either the Anthropoidea or the 

 modern Lemurs, exclusive of Tarsius and Dauhentonia with the sin- 

 gle possible exception of the South American squirrel-monkey group, 

 which may have been derived from some member of this group more 

 nearly related to the Notharctinae as suggested by Wortman, The 

 special trend in development, as indicated by modifications of the 

 anterior teeth, in many of these forms would alone seem not to be 

 consistent with such a conclusion. Moreover, the skull and limb 

 characters, so far as known, likewise indicate Tarsius affinities; hence 

 it would seem that, as regards the relationship of this group of early 

 Primates to the modern members of the order, it may be assumed 

 that the most which can be claimed on present evidence is, that 

 among the living Primates, the Tarsiers, only, are probable descend- 

 ants of some as yet unknown genus of the group. Possibly, also but 

 I think not probably, some genus now considered a member of the 

 early Tarsiids may have given origin to the group represented by 

 the modern Aye Aye (Dauhentonia) . 



These conclusions regarding the phylogenetic position of the early 

 Tarsiids are, in my opinion, greatly strengthened, and, to a degree, 

 verified by the additional knowledge gained from the Fort Union 

 members of the family. Although indicating a somewhat less spe- 

 cialized development, these older genera are apparently little or no 

 nearer the condition required of a root group than are their relatives 

 of the Wasatch and Bridger. their evolutionary trend being as clearly 

 indicated as in the latter. Thus the evidence seems rather clear that 

 the Tarsiidae represent a very ancient major group of the order hav- 

 ing a pre-Tertiary origin, possibly in common with the Anthropoidea, 

 but developing, at least from the beginning of the Tertiary on, inde- 

 pendently of either the anthropoids or true lemurs. This would seem 

 to support Wortman 's view in so far as he regarded Tarsius and its 

 nearer Eocene relatives as having Anthropoidea affinities; but it 

 lends no support to his seemingly unnatural association in which he 

 placed a part of the Tarsiidae with the Hapalidae under a major 

 group of this suborder. The little marmosets, as rightly contended 

 by Gregory, give every evidence of having had a common origin with 

 the other families of the so-called Platyrrhinae and should not be 

 separated from that group despite the unique features among modern 

 Primates of the claw-like terminal phalanges and the nonopposability 

 of the pollex. I do not, however, agree with Gregory's expressed 

 belief, that these are either retrogressive or specialized characters, 

 but believe rather, as I have formerly held, ^® that both characters 

 pertain to a primitive condition retained in this particular group 

 because of their very diminutive size and slight weight, which did 



16 Washington Acad. Sci. Proc, vol. 9, 1919, p. 277. 



