Archaeolagus, DICE, 1917

Maguire, Kaitlin Clare & Schmitz, Joshua X. Samuels and Mark D., 2018, The fauna and chronostratigraphy of the middle Miocene Mascall type area, John Day Basin, Oregon, USA, PaleoBios 35, pp. 1-51 : 17

ARCHAEOLAGUS DICE, 1917

Archaeolagus sp.

FIG. 8E

Referred specimens —left M1 or M2, JODA 17386.

Occurrence —JDNM-71A.

Description —The tooth has a strong, straight-walled cement-filled hypostria (lingual reentrant) crossing about halfway across the occusal surface of the tooth. Though the posterolabial corner of the tooth is missing, enamel is clearly absent from labial margin of tooth. There is an isolated chevron just labial to the hypostria. Anteriorposterior length is 2.08 mm and transverse width is 3.63 mm.

Remarks —This tooth is very similar to Archaeolagus specimens from the John Day Formation, which range from base of the Turtle Cove Member (Whitneyan) through the Johnson Canyon Member (late Arikareean) and are particularly abundant in upper John Day strata ( Samuels and Kraatz 2015). There are at least two species of Archaeolagus known from the John Day Formation, A. ennisianus Cope, 1881 and A. primigenius Matthew, 1907 , both of which are similar in morphology to the Mascall specimen. JODA 17386 falls within the range of size variation for M1 samples of those two species in Oregon: A. ennisianus (n=16) M1ap mean= 2.01 mm (range= 1.89–2.19 mm), M 1t mean= 3.58 mm (range= 2.95–3.89 mm); A. primigenius (n=6) M1ap mean= 2.06 mm (range= 1.95–2.17 mm), M 1t mean= 3.46 mm (range= 3.29–3.71 mm). This record is much younger than others in Oregon and may be the latest known occurrence of the genus, later than all records listed in Dawson (2008).

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