Synonyms. Lagurus curtatus.
The nearest approaches of the Sagebrush Vole to our region today are in south-central Utah, northern Colorado, and along the eastern border of California (Fig. 1). According to Carroll and Genoways (1980), Artemisia spp. (sagebrush) and Agropogon spp. (crested wheatgrass) usually are dominant plants in their habitat, although Chrysothamnus spp. (Rabbitbrush) also may be a dominant component. They do occur in habitats with heavy grass and various annuals, but such conditions are considered atypical. Lemmiscus curtatus is one of several taxa strongly suggesting sagebrush grasslands were an important vegetative type throughout New Mexico and, likely, beyond.
Fig. 1. Current distribution of Lemmiscus curtatus. Map adapted from Carroll and Genoways (1980).
The arvicoline dentary and its first two molars are commonly preserved as fossils and thus usually important in identification. Lemmiscus is most likely to be confused with members of the genus Microtus. Both have prismatic, ever-growing cheek teeth and the general characteristics of voles. Overall, the impression of Lemmiscus is of a more lightly built, more delicate animal than the various species of Microtus. Figures 2 through 4 illustrate some of the typical conditions of the lower jaw of Lemmiscus and some differences from Microtus. The teeth (Fig. 2) generally are recognizable by the more open reentrant angles and somewhat more rounded contours. The masseteric scar (Fig. 3) is notably more acute anteriorly than in Microtus, and the mandibular foramen (Fig. 4) is not visible when viewed from the lingual side, unlike the situation in Microtus.
Fig. 2 (left). Dorsal view of the right m/1 and m/2 of Lemmiscus curtatus (UTEP 22-3167) from the Animal Fair site, Dry Cave.
Fig. 3 (right). Lateral view of fossil Lemmiscus (UTEP 22-3164) dentary showing the typical shape of the masseteric scar (outlined on the upper image of the figure).
Fig. 4. Internal views of the dentaries of a Microtus (top) and a fossil Lemmiscus (UTEP 22-3164) to show the difference in position of the mandibular foramen. The foramen is visible at the lower end of the black line in Microtus. The black line on the Lemmiscus dentary indicates the position of the foramen, unseen because hidden behind the ridge formed by the incisor.
Modern Lemmiscus first lower molars have five (occasionally six) closed triangles (Fig. 2). Fossil Lemmiscus faunas may include specimens with only four closed triangles (the SAM Cave morphotype), with the proportion of such tending to increase with the age of the fauna (Rodgers et al. 2000). The morphotype disappears from the SAM Cave deposits by 0.78 mya (Rogers et al. 2000), but has been recovered from Snake Creek Burial Cave in eastern Nevada with a date of less than 15,000 ka (Bell and Mead 1998).
Medial Irvingtonian: SAM Cave (Rogers et al. 2000).
Rancholabrean: Pit Stop Quarry (Murray et al. 2005)
Wisconsin: Big Manhole Cave (Harris 1993c); CC:5:1 (Mead et al. 2003); Whut Cave (Smartt and Hafner 1989).
Mid Wisconsin: Pendejo Cave (Harris 2003); Screaming Neotoma Cave (Bell and Glennon 2003); U-Bar Cave (Harris 1987).
Mid/Late Wisconsin: Dark Canyon Cave (Harris 1993c).
Late Wisconsin: Algerita Blossom Cave (Harris 1993c); Animal Fair 18-20 ka (Harris 1993c); Antelope Cave (Reynolds, Reynolds, Bell, and Pitzer 1991); Bison Chamber (Harris 1970a); Camel Room (Harris 1993c); Charlies Parlor (Harris 1993c); Harris' Pocket (Harris 1970a); Human Corridor (Harris 1993c); Screaming Neotoma Cave (Bell and Glennon 2003); Sheep Camp Shelter (Gillespie 1985); Stalag 17 (Harris 1993c); TT II (Harris 1993c); U-Bar Cave 13-14 ka (Harris 1989); U-Bar Cave 15-18 ka (Harris 1989); U-Bar Cave 18-20 ka (Harris 1989).
Late Wisconsin/Holocene: Atlatl Cave (Harris 1993c); Balcony Room (Harris 1993c); Boyd's Cave (Harris 1993c); Burnet Cave (Schultz and Howard 1935); Hermits Cave (Harris ID); Howell's Ridge Cave (Harris 1993c); Isleta Cave No. 1 (Harris 1993c); Isleta Cave No. 2 (Harris 1993c); Kokoweef Cave (Reynolds, Reynolds, et al. 1991); Pendejo Cave (Harris 2003).
Literature. Bell and Glennon 2003; Bell and Mead 1998; Carroll and Genoways 1980; Gillespie 1985; Harris 1970a, 1987, 1989, 1993c, 2003; Jefferson 1991b; Mead et al. 2003; Murray et al. 2005; 1991b; Reynolds, Reynolds, et al. 1991; Reynolds, Reynolds, Bell, and Pitzer 1991; Rogers et al. 2000; Schultz and Howard 1935; Smartt and Hafner 1989.
Last Update: 27 May 2014