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Class Mammalia
Order Rodentia
Family Cricetidae
Subfamily Neotominae
Genus Neotoma


Neotoma mexicana Baird 1855—Mexican WoodratRegional Pleistocene distribution of Neotoma mexicana.

Neotoma mexicana dentary
Neotoma mexicana is widespread in our region, but generally limited to higher elevations (woodlands or above). In a few cases, including some lava fields and rock flows, it descends to lower elevations.

Fig. 1. Right dentary of a Mexican Woodrat (UTEP 32-514) from Howell's Ridge Cave. Millimeter scale.

In earlier published comments on N. mexicana, I suggested that the taxon was absent from east of the Rio Grande until late in the Wisconsin. Logan and Black (1979) had apparently identified fossil N. mexicana from the Guadalupe Mountains on the basis of the lack of accessory cusps in tooth reentrants whereas cinerea/mexicana-like teeth with accessory cusps were identified as N. cinerea. However, Logan and Black noted themselves that 50% of modern N. cinerea teeth lack such cusps; thus cuspless teeth could as easily represent N. cinerea as N. mexicana. Logan (1983) identified N. cinerea teeth from Lower Sloth Cave on the basis of accessory cusps (which he found in one or more teeth in five out of eight modern specimens) and, on worn teeth, the presence of enamel islands as left-overs from "socketed" reentrants; thus, by implication, N. mexicana was identified by the lack of accessory cusps or, on worn teeth, of enamel islands. Logan also identified, from Dust Cave (close by Upper and Lower Sloth caves), 34 lower first molars of high-dentine tract woodrats that were meaningfully measurable, with 12 possessing accessory cusps. Two of the 34 might possibly represent N. mexicana, but could possibly represent N. cinerea, instead. Thus it seemed that presence of N. mexicana was not proven. Since the above was written, I have seen the specimens from Lower Sloth Cave identified as N. mexicana by Logan (1983) and agree that they definitely do represent that species.

Farther west, at Pendejo Cave, N. mexicana has been identified from Zone C (mixed Pleistocene and Holocene) and Zone C2. Zone C2 has several radiocarbon dates ranging from 12,240 ± 70 to 12,970 ± 170.

In August of 2012, a more comprehensive study of N. cinerea- and N. mexicana-like first lower molars was undertaken. Neotoma mexicana now has been identified with reasonable assuredness from pre-pleniglacial deposits of Animal Fair (Grid D, levels 4 and 7) along with further specimens from the upper levels of Dry Cave's Balcony Room. They appear to be absent during the more severe portions of the late Wisconsin, however.

Occurrence in the Holocene at relatively low elevations compared to today occurred in the Holocene Entrance Chamber deposits at Dry Cave and at the Khulo Site west of the Rio Grande (Harris 1984b). It is unclear whether these low-elevation occurrences were allowed by more compatible climatic conditions in the early Holocene or whether extirpation was due to degeneration of habitat following the introduction of livestock into the region.


Late Pleistocene: Wanis View (Jefferson 2014).

Mid Wisconsin: Papago Springs Cave (Czaplewski and Mead et al. 1999: cf.); U-Bar Cave (Harris 1987).

Late Wisconsin: Animal Fair (UTEP); Balcony Room (UTEP); Dust Cave (Harris and Hearst 2012: cf.); Lower Sloth Cave (Logan 1983); Muskox Cave (Logan 1981); Pendejo Cave (Harris 2003); Rampart Cave (Van Devender et al. 1977: cf.); TT II (UTEP); U-Bar Cave 13-14 ka (Harris 1989); U-Bar Cave 14-15 ka (Harris 1989); U-Bar Cave 15-18 ka (Harris 1989); U-Bar 18-20 ka (Harris 1989); Upper Sloth Cave (Logan and Black 1979).

Late Wisconsin/Holocene: Baldy Peak Cave (Harris 1984b); Burnet Cave (Schultz and Howard 1935: cf.); Fowlkes Cave (Dalquest and Stangl 1984b); Howell's Ridge Cave (Harris 1993c); Pendejo Cave (Harris 2003).

Holocene: Khulo Site (Harris 1984b); Entrance Chamber, Dry Cave (Harris 1984b).

Literature. Czaplewski and Mead et al. 1999; Dalquest and Stangl 1984b; Harris 1984b, 1987, 1989, 1993c, 2003; Harris and Hearst 2012; Jefferson 2014; Logan 1981, 1983; Logan and Black 1979; Schultz and Howard 1985; Van Devender et al. 1977.


Last Update: 29 May 2015