PROTOREODON 37 



Protoreodon parvus Scott and Osborn 1887 

 Fig. 12; PI. I, fig. 3 



Original Reference: Preliminary report on the vertebrate fossils of the Uinta formation, collected by the 

 Princeton expedition of 1886. Proc. Amer. Philos. Soc, XXIV, pp. 257-258, 1 fig. 



Type Locality: Uinta County, Utah. 



Geologic Horizon: Upper Eocene (Uinta — Hor. B). 



Types: Genoholotype, Cat. No. 10398 P.U.M., palate and fragment of left ramus. Paratypes, Cat. Nos. 

 11535 and 12216 P.U.M., skull and jaws and parts of skeleton. 



Specific Characters: The skull length is about one-eighth less than that of P. pumilus, 

 which it strongly resembles in its general proportions. In fact, Marsh considered it to be the same 

 as his species. However, differences between the two forms do exist. In general this is a smaller 

 skull. The zygomatic arch does not rise posteriorly, as it does in P. pumilus, but is nearly hori- 

 zontal with the tooth row. The supraoccipital crest is slightly more produced beyond the condyles. 

 The lower jaw is slenderer, the chin profile very slightly convex, and the masseteric fossa larger. 



The infraorbital foramen is situated a trifle more forward, above the anterior of P 3 . 



Dentition: The tooth proportions are very similar to those of P. pumilus. The main distinc- 

 tions lie in the premolars. The inner cone of P 4 is larger and wider; the posterior crescent of P 2 

 and of P 3 is larger, and there is no diastema between P 1 and P 2 . The styles on the molars are 

 perhaps slightly less rounded and slightly smaller. The canine is less robust. In other respects the 

 similarity is very apparent. The superior molar-premolar index is 1.08 and the inferior 1.00. 



Discussion: This skull, like all the others in this genus that I have seen, has suffered a cer- 

 tain amount of crushing, and consequently transverse measurements are often not exact enough to 

 be of high value. With the exception of the differences in the premolars cited above and of the 

 inferior premolar series, which is slightly shorter in relation to the molar series, I can see no impor- 

 tant differences between the types of the two species. P. parvus in fact may well be the female 

 form of P. pumilus. At any rate they are very closely related. 



Osborn (1929, pp. 99-100) records two specimens of this species found at Beaver Divide, 

 Wind River Basin, Wyoming. The horizon is Uinta, either the summit of Horizon B or the base 

 of Horizon C. 



Protoreodon pumilus (Marsh) 1875 

 Figs. 13-15 



Original Reference: Notice of new Tertiary mammals. IV. Amer. Jour. Sci. (3), IX, p. 250 

 (/f griochcerus fumilus). 



Synonym: Eomeryx fumilus Marsh 1894. 



Type Locality: White River, Utah. 



Geologic Horizon: Upper Eocene (Uinta, probably Hor. C). 



Types: Cotypes, Cat. No. 1 1890 Y.P.M., lower jaw, small portion of skull, and fragmentary limb bones; 

 Cat. No. 11890a Y.P.M., fragment of maxilla with molars; and Cat. No. 11890b Y.P.M., foot bones. Para- 

 types, Cat. No. 11891 Y.P.M., skull, with atlas and part of axis attached, mandibles, and very fragmentary 

 skeletal parts; Cat. No. 10570 Y.P.M., pair of lower jaws. This type material was collected by Professor 

 Marsh (1870), J. Heisey and S. Smith (1874), and J. W. Chew and Matt Forshey (1877). 



Specific Characters: The skull is small, not more than 160 mm. in length, and is doli- 

 chocephalic. It has been laterally crushed to some extent. The maximum expansion of the 

 zygomata lies just anterior to the glenoid surface. The malar is narrow, and the squamous portion 

 of the zygomata is somewhat wider than the malar. The arch ascends gradually aft to its crest above 

 the glenoid articular surface, about to the level of a plane through the middle of the orbits. The 



