NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 7 



C. Occurrences in the Duchesne River formation, however, are 

 exceedingly rare. 



In the Washakie Basin the upper or B portion of the Washakie 

 formation is regarded as upper Eocene and generally considered to be 

 about equivalent in age to the Wagonhound or lower part of the 

 Uinta formation. So far the only artiodactyl remains known to have 

 been found in the Washakie beds are of Achaenodon, a questionable 

 Protylopus, and Homacodon. The Achaenodon and (?)Protylopus 

 specimens are from Washakie B, whereas Homacodon is from Washa- 

 kie A, according to Granger (1909). In addition to these, Parahyus 

 vagus, as will be discussed in the systematic treatment of the species, 

 was based on a specimen that almost certainly came from the Washa- 

 kie, and likely from a horizon nearly transitional between A and B. 



The occurrence of upper Eocene strata in the Wind River Basin is 

 divided between a narrow zone along the north side of the basin and 

 the Beaver Divide forming the rim to the south. To the north, par- 

 ticularly along the south side of Bad water Creek, remains have been 

 obtained of a variety of artiodactyls, including a homacodont, possibly 

 Pentacemyhis, leptotragulids, and oromerycids, as well as Protoreodon 

 and Diplobunops. Somewhat farther west near Dry Creek the oro- 

 merycid Malaquiferus was discovered. As far as can be determined 

 from the fauna as a whole, these Artiodactyla are upper Uintan in 

 age, probably Uinta C, rather than Duchesnean. 



Much confusion exists as to the relative ages of horizons repre- 

 sented in the sequence exposed along the Beaver Divide at the southern 

 rim of the Wind River Basin. Uintan beds here have produced 

 Camelodon arapahovius and probably several of the specimens of un- 

 certain locality which have been attributed to the Beaver Divide 

 conglomerate. The top of the Uintan sequence is deeply channeled, 

 and the fill has produced remains of Oligocene age. At least one of 

 these, the Brachyhyops zvyomingensis skull, was described as coming 

 from the uppermost part of the Uintan sequence. I am informed by 

 Dr. Franklyn B. Van Houten - that the Beaver Divide conglomerate 

 overlies the channel fill and so is likewise Oligocene in age. The ma- 

 terials of Eocene aspect attributed to the Beaver Divide conglomerate 

 are for the most part uncertain as to locality, particularly the immature 

 specimen described by Scott as Mesagriochoerus primus, collected by 

 a local resident. The type of Protoreodon tardus was found by 

 J. LeRoy Kay but this is a relatively early protoreodont, presumably 

 not as late as Duchesnean and surely not later than Eocene. For an ex- 



2 Personal communication. 



