INTRODUCTION

One of the major, if not the major, contribution of the late Charles A. Repenning to paleontology was to increase our understanding of the evolutionary relationships, biostratigraphy, and paleobiogeography of arvicoline rodents. Although he published on all arvicoline groups, perhaps his greatest interest was in those species historically considered to be part of or closely related to Microtus (i.e., Arvicolini; Galewski et al., 2006). Therefore, it seems appropriate in a volume honoring Charles Repenning that we report and discuss specimens assignable to Arvicolini from a new site in north-central Kansas, the Fiene local fauna (l.f.).

The Fiene l.f., located in Smith County (Co.), is one of a small number of Pleistocene localities in Kansas outside the Meade Basin (Figure 1.1). The fossils from this locality include more than 40 identifiable taxa of actinopterygians, amphibians, reptiles (including birds), mammals, and both aquatic and terrestrial molluscs (Bever et al., 1999). The geologic setting of Fiene consists of relatively thin deposits of reddish clayey sands and silts containing caliche nodules deposited over Cretaceous limestone. The nature of the sediments, interpreted within the context of their associated fauna, suggests both lacustrine and fluvial influences, and we hypothesize that the locality was deposited within an oxbow lake. No external age control currently exists for the site, and the recognized stratigraphic division to which the Fiene sediments belong (if any exists) is unclear. The Pleistocene localities geographically closest to Fiene are Courtland Canal and Hall Ash Pit—approximately 60 km to the east (Eshelman and Hager, 1984). The lithologically similar sediments of these localities (to those of Fiene) were suggested by Eshelman and Hager (1984) to be equivalent in part to the Loveland Formation (Frye and Leonard, 1952). The section containing the Hall Ash Pit contains a bedded ash that was fission-track dated to a mean age of 0.706 ± 0.017 Ma (Eshelman and Hager, 1984). A better understanding of the lithologic and stratigraphic relationships between the Pleistocene localities of north-central Kansas and with the classic sequences of the Meade Basin is needed.

Based on the occlusal pattern of the first lower molar (m1), seven different Arvicolini morphotypes can be distinguished. These include one form with five closed triangles assigned to Microtus sp.; three morphotypes with four closed triangles, all assigned to M. paroperarius as Variants A, B, C; and three morphotypes with three closed triangles assigned to M. llanensis, M. meadensis, and Allophaiomys sp. The only other sites (Figure 1.2) where at least four of these species occur together are Cathedral Cave, White Pine Co., Nevada (Bell, 1995; Jass, 2006, 2007), Porcupine Cave, Park Co., Colorado, in the Pit (level 4) and CM Velvet Room (level 3) sites (Bell et al., 2004a), and Cudahy, Meade Co., Kansas (Paulson, 1961; Bell and Repenning, 1999). Four of the taxa also may occur at Hansen Bluff, Alamosa Co., Colorado (Bell et al., 2004a), but the Allophaiomys record from Hansen Bluff (Rogers et al., 1992, figure 9A) is based on an isolated lower third molar (m3), which is a non-diagnostic element at the generic level (Bell and Barnosky, 2000). Microtus llanensis does not occur in the Colorado and Nevada sites, and Allophaiomys sp. is not found at Cudahy.

Other sites in Kansas, outside the Meade Basin, from which at least one of the taxa found at Fiene include Hall Ash Pit (Microtus sp., M. paroperarius) and Courtland Canal (Allophaiomys sp.) in Jewell Co., Kanopolis (M. llanensis) in Ellsworth Co., Kentuck (Allophaiomys sp.) in McPherson Co., and Wathena (Allophaiomys sp.) in Doniphan Co. (Figure 1.1). Other non-Kansas sites mentioned in this study (Figure 1.2) include Irvington (California), Java (South Dakota), Vera (Texas), Conard Fissure (Arkansas), Trout Cave #2 (West Virginia), and Cumberland Cave (Maryland).