Kill 



osborn: oligocene, miocene, pltocene equid^:. 



Hipparion anthonyi Merriam 191 G. 

 Text Fig. 153. 



Hipparion anthonyi n. sp., Merriam, John C. "Mammalian Remains from a Late Tertiary Formation at Ironside, Oregon," Univ. 

 Cal. Publ. Bull. Dept. Geol. Vol. 10, No. 9, Dec. 1916, pp. 131-133, figs, la, lb, lc. 



Horizon and locality. — (Merriam, pp. 130-131) "....from Tertiary beds exposed three-fourths of a mile south 

 of Ironside, Malheur County, Oregon. . . .The horizon at which this specimen was found is presumed to be early Plio- 

 cene, or latest Miocene. . . .The Ironside region, in which the mammalian finds are reported, is situated on the extreme 

 northern border of Malheur County, Oregon, and is about thirty miles west of the middle of the eastern border of the 

 state. This region lies at the southeastern base of the Blue Mountains, and is at the northern end of the great series of 

 broken plains and short mountain ranges extending through southeastern Oregon into Nevada. The Ironside region is 

 drained by Willow Creek, a tributary of Malheur River. . . .The mammal-bearing formation consists of buff sandy shales 



Fig. 153. Original figures of the type of Hipparion anthonyi Merriam, Univ. Cal. Pal. Coll. 22351, p2 of the right 

 side. (In) Occlusal view, (lb) outer view, (lc) inner view. Natural size. After Merriam, 1910, p. 132. 



and shales with but little sand. The beds stand at varying angles ranging up to a degree of inclination of at least 20 degrees. 

 Locality 3037, at which the most important specimens were found, is located about three-fourths of a mile southwest of 

 Ironside Post Office." 



Type. — (Merriam, p. 131.) "Type specimen a second lower premolar, no. 22351 [Univ. Cal. Pal. Coll.]". 

 Type figure. — Text Fig. 153 of this Memoir. 



Characters. — (Merriam, 1910, pp. 131-132) [The type] "Crown of medium height, narrow transversely. Enamel 

 pattern showing uncommonly strong secondary plications. Several very strong secondary plications forming a sheaf 

 of projecting folds on anterior side of hypoconid. Specimen 22351 (Figs, la to lc) [the type] differs from Merychippus and 

 Pliohippus in its greater relative size and stage of advance of the metaconid-metastylid column and entoconid, and in 

 greater complication of its enamel folds. Of the Great Basin and Pacific Coast province equids Hipparion mohavense 

 callodonte of the Ricardo Pliocene most nearly approaches the form from Ironside. In the West Coast Merychippus and 

 Pliohippus species the metaconid-metastylid column is relatively shorter anteroposteriorly, and wider transversely, and 

 the entoconid is not filled out to the same extent on the antero-internal angle. In general the entoconid of Merychippus 

 and Pliohippus species is truncated obliquely on the antero-internal angle by a plane or curved face, extending outward 

 and forward from the inner side, while in Hipparion this region is expanded and the cross-section of the entoconid tends 

 to take on a rectangular outline, instead of the approximately triangular section seen in Merychippus, or the triangular 

 to imperfectly rectangular but anteroposteriorly short section seen in Pliohippus." 



