Kalobatippus, OS

Maguire, Kaitlin Clare & Schmitz, Joshua X. Samuels and Mark D., 2022, The fauna and chronostratigraphy of the middle Miocene Mascall type area, John Day Basin, Oregon, USA, PaleoBios 35, pp. 1-51 : 23

CF. KALOBATIPPUS OS �ORN, 1915

FIG.13

Referred specimen —Left dp2, UCMP 312849.

Occurrence —RV6855.

Description —UCMP 312849 is a well-worn, low-crowned, lower deciduous second premolar in the size range of Kalobatippus (ap=19.8, t= 14 mm). The metaconid and protoconid are joined by a protolophid, the entoconid and hypoconid are joined by a hypolophid, and the cristid obliqua joins with the protolophid between the protoconid and metaconid.

Remarks —There is no locality data for RV6855; only that it is an old CIT location, labeled from the Mascall Formation, Oregon. Therefore, this specimen is tentatively placed on the faunal list. Another specimen of Kalobatippus (UCMP 1702) was collected from the Crooked River locality UCMP V4949. UCMP 1702 is a partial molar or premolar with a part of the base of the protocone, one half of the metaloph, a small internal section of the metacone and all of the hypostyle is present. It is too small to be Hypohippus Leidy, 1858 (approximate molar length: M1/ M2= 27.5 mm; m1/m2=26.0 mm) and is closer in size to Kalobatippus (approximate molar length: M1/M2=17.0 mm; m1/m2=19.0 mm) ( MacFadden 1998). Downs (1956) assigned this specimen to cf. Hypohippus based on size; however, he could not rule out Kalobatippus . Comparison of these specimens to Hypohippus specimens from the Virgin Valley fauna indicate that it is too small to be attributed to that genus and most likely belongs to Kalobatippus . Hunt and Stepleton (2004) also reported cf. Kalobatippus from the Upper John Day Formation, from the late Arikareean age Johnson Canyon Member and the Hemingfordian age Rose Creek Member strata south of Kimberly, OR; and also from Upper John Day Formation strata at Sutton Mountain, near Mitchell, OR.

Figures

Figure 13. cf. Kalobatippus sp. left dp2 in occlusal view, UCR 312849. Scale bar=3mm.