LEPORIDAE FISCHER VON WALDHEIM, 1817

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 : 16-17

LEPORIDAE FISCHER VON WALDHEIM, 1817 HYPOLAGUS DICE, 1917

Hypolagus fontinalis DAWSON, 1958 FIG. 8A , �

Referred specimens —From UCMP V 4833: left p3, UCMP 41205; left p3, JODA 4283.

Occurrence — UCMP V 4833.

Description —UCMP41205 has a posteriorly inflected posteroexternal reentrant (PER) and a well-incised anteroexternal reentrant (AER). PER is uncrenulated and larger than in H. parviplicatus Dawson 1958 . The third premolar has an anteroposterior length of 3.04 mm and transverse width of 2.42 mm. Based on the posteriorly inflected PER and smaller size than H. parviplicatus this specimen is assigned to H. fontinalis . The PER on JODA 4283 is not inflected posteriorly and there are no crenulations on the thin enamel of the PER (TN). The anteroposterior length is 2.86 mm and the transverse width is 2.1 mm falling within the size range for H. fontinalus ( Voorhies and Timperley 1997) . This specimen is placed in this taxon based on the uncrenulated TN and size.

Remarks —This is the first record of this species in the Barstovian of Oregon. The sizes of the Mascall H. fontinalis specimens fall between the average measurements for H. fontinalis and H. parviplicatus in Voorhies and Timperley (1997), but within the range of variation of the former. Hypolagus fontinalis differs from the other Barstovian species H. tedfordi White, 1988 , H. parvipla- catus, and H. cf. voorhiesi White, 1988 in the following ways: it differs from H. tedfordi in the posterior deflec- tion of the PER and its larger ap length; it differs from H. parviplicatus in its smaller size, more well-incised AER, and an uncrenulated TN on the PER; and from all other species of Hypolagus in having a shallower incision of the PER ( White 1988).

Hypolagus parviplicatus DAWSON, 1958 FIG. 8C, D

Referred Specimens —From JDNM-4*: left p3, JODA

2326; left dentary with p3 through m2, JODA 2328. FROM

CIT 183: right p3, CIT 4002. Occurrence —JDNM-4*, CIT 183*.

Description —JODA 2326 does not have an inflected PER, AER is very shallow, thick enamel in PER (TH) is crenulated, ap= 3.07 mm and t=3.15. The transverse width places this specimen within the size range of H. parviplicatus ( Voorhies and Timperley 1997) . The p3 of JODA 2328 has a shallow AER, the PER is straight with no crenulations on the TN, ap= 3.04 mm and t= 3.26 mm also consistent with placing the specimen in H. parviplicatus . CIT 4002 has a shallow AER and the PER does not inflect posteriorly. Unfortunately, the PER is not preserved well enough to make out whether the TN is crenulated, as is characteristic of H. parviplicatus . The specimen has an anteroposterior length of 2.96 mm and a transverse width of 3.01 mm, which is on the smaller end of the size range of the species, closer to H. fontinalus .

Remarks —CIT 4002 also contains three lower molars and one upper molar. All of these specimens were found in isolation by Weatherfords; therefore, we are hesitant to attribute them to the same species as CIT 4002, given that they cannot be distinguished morphologically and such assignment would be based on presumed age, thus introducing circularity. Instead, the Weatherford specimens are referred to Leporidae indet. and discussed below. This is the first record of this species in Oregon. The specimens differ from other Barstovian species of Hypolagus in the following ways: it is larger and has a less well incised AER than H. fontinalis and H. tedfordi , and from all other species in its less incised PER.

Figures

Figure 8. Leporidae. A, B. Hypolagus fontinalis left p3, UCMP 41205 (A),JODA 4283 (B). C, D. Hypolagus parviplicatus left p3, JODA 2328 (C); JODA 2326 (D). E. Archaeolagus sp. left M1 or M2, JODA 17386. All in occlusal view. Scale bar=1mm