Palaeogale dorothiae MacDonald, 1963

Famoso, Nicholas A. & Orcutt, John D., 2022, First occurrences of Palaeogale von Meyer, 1846 in the Pacific Northwest, United States, Geodiversitas 44 (14), pp. 427-436 : 432

Palaeogale dorothiae MacDonald, 1963

( Fig. 3 ; Table 2 )

REFERRED SPECIMENS. — JODA 6177 left fragmentary dentary with p4-m1. JODA 5893 right fragmentary dentary with p2 and p4.

OCCURRENCE. — JDNM-140, Lonerock, Gilliam County, Oregon, USA. Kimberly Member, John Day Formation. Precise locality information available to qualified researchers upon request.

AGE. — Late Oligocene in the Late Arikareean (Ar3) NALMA, between the Tin Roof Tuff (25.3 Ma) and the UNSM JD-BC-3 tuff (23.5-23.8 Ma) ( Fremd & Whistler 2009).

SPECIES DIAGNOSIS. — The p4 is without a posterior accessory cusp and the protoconid of the m1 is not expanded laterally ( MacDonald 1963).

DESCRIPTION

JODA 5893 has no posterior accessory cusp on p4; however, there is a small enamel anomaly on the posterior edge. There is an alveolus for p3. The p2 crown is stretched forward with an upturned posterior heel. JODA 6177 is broken behind the c, and there is no p2 alveoli. There is no p4 accessory cusp. The m1 protoconid is not expanded laterally. See Table 2 for measurements of both specimens.

COMPARISON

Both specimens match the species diagnosis in the absence of the p4 accessory cusp. They are both too large to be P. minuta . In JODA 5893, the morphology of the p4 is similar to P. sectoria (Lange-Badre & Dashzeveg 1989; Wang & Zhang 2015). The size of JODA 6177 is comparable to P. sectoria from Mongolia but the protoconid of the m1 is not expanded (Lange-Badre & Dashzeveg 1989; Wang & Zhang 2015). The type specimen is from the Sharps Formation of South Dakota which is 30-28.6 Ma ( MacDonald 1963; McConnell & DiBenedetto 2012). Swisher (1982) states that this species is also known from the Brown Siltstone Beds or Whitney Member of the Brule Formation (c. 31-30 Ma) and the Unit B Member of the Gering Formation (28.26-28.11 Ma) both of Nebraska ( Tedford et al. 1996, 2004). This makes the Lonerock specimens, which are between 25.3 and 23.8 Ma, the latest known occurrences of this species.

Figures

FIG. 3. — Dentaries of Palaeogale dorothiae MacDonald, 1963: A, lingual view (JODA 6177);B, occlusal view (JODA 6177);C, buccal view (JODA 6177); D, lingual view (JODA 5893); E, occlusal view (JODA 5893); F, buccal view (JODA 5893). Scale bars: 1 cm.