Gingerichia sp. 1

Zack, Shawn P., Penkrot, Tonya A., Krause, David W. & Maas, Mary C., 2005, A new apheliscine “ condylarth ” mammal from the late Paleocene of Montana and Alberta and the phylogeny of “ hyopsodontids ”, Acta Palaeontologica Polonica 50 (4), pp. 809-830 : 818-819

Gingerichia sp. 1

Fig. 4F, Table 2.

Referred material.—UM 54895, right p4.

Age and distribution.— Gingerichia sp. 1 is known only from Bingo Quarry in the eastern Crazy Mountains Basin , south−central Montana, which is of early Tiffanian (Ti1) age ( Hartman and Krause 1993).

Description.—UM 93348 is heavily worn, which limits the amount that can be said about it. The protoconid is large, as in other Gingerichia , but probably somewhat less inflated. A very small paraconid connected to a short, weak anterior cingulid is retained. The degree of wear makes it impossible to determine if a metaconid was present as well. The talonid appears to have been bicuspid, although the buccal cusp has been largely obliterated by wear. Although small, the talonid of UM 93348 is somewhat wider and more basined than in other p4s of Gingerichia . As is typical of the genus, the buccal enamel beneath the talonid is distended ventrally. The posterior cingulid is sharper than in other Gingerichia p4s, potentially a reflection of the generally less inflated crown.

Discussion.—A probable third species of Gingerichia is represented by a single, worn p4 from Bingo Quarry, the earliest Tiffanian locality in the Crazy Mountains Basin. The very small size, weakly inflated p4 trigonid, and less reduced talonid of UM 93348 appear to be primitive features for Apheliscinae and argue against its allocation to either G. geoteretes or G. hystrix . We consider it inadvisable, however, to name a new species of apheliscine on the basis of a single worn tooth. UM 93348 is nonetheless significant as it provides the most plesiomorphic record of the genus, while demonstrating that the distinctive features of both Apheliscinae and Gingerichia were already developed in the earliest Tiffanian.

Bingo Quarry lies stratigraphically below both Douglass and Glennie quarries ( Hartman and Krause 1993), both of which have yielded specimens of G. geoteretes (see above). Gingerichia species 1 appears not only to be primitive relative to G. geoteretes from Douglass and Glennie quarries but also relative to G. hystrix from Cochrane 2. This suggests that Cochrane 2 is younger than Bingo Quarry but older than Douglass and Glennie quarries. Discovery of G. hystrix in the Crazy Mountains Basin would provide a test of this tentative conclusion.