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Class Mammalia
Order Rodentia
Family Geomyidae

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Geomys sp.—Eastern Pocket Gophers // Geomys (Nerterogeomys) sp.—Nerterogeomys Pocket Gophers // Geomys minor—Small Pocket Gopher // Geomys paenebursarius—Early Plains Gopher // Geomys arenarius/bursarius—Desert or Plains Pocket Gopher // Geomys bursarius—Plains Pocket Gophers // Geomys persimilis—Hay's Pocket Gopher

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Geomys—Eastern Pocket Gophers

Several characters often preserved in the fossil record identify the genus Geomys (see the Geomyidae account). Discrimination of species, however, is problematical. Our region has representatives of three living species: Geomys arenarius, G. bursarius, and G. knoxjonesi. The latter is recognized primarily on the basis of genetical data and occurs in southeastern New Mexico and adjacent Texas; the first two have only minor morphological differences seldom observable in fossils. Geomys arenarius occurs in the southern Rio Grande Valley and environs in New Mexico; G. bursarius mostly to the northeast. The accounts follow the identifications given in the publications except the Navar Ranch and Tank Trap Wash records; at the time these were published, G. arenarius was included in G. bursarius. Likely all listed under G. arenarius/bursarius are G. arenarius, but they are not identifiable on the material available.

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Geomys sp.—Eastern Pocket GophersPleistocene distribution of Geomys sp.

Sites.

Late Blancan/Early Irvingtonian: Elsinore: Mimomys (Pajak et al. 1996).

Irvingtonian: El Golfo (Croxen et al. 2007).

Mid/Late Wisconsin/Holocene: Sierra Diablo Cave (UTEP).

Late Wisconsin/Holocene: Conkling Cavern (Harris 1993c); Pendejo Cave (Harris 2003).

Literature. Croxen et al. 2007; Harris 1993c, 2003; Pajak et al. 1996.

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Geomys (Nerterogeomys) sp.—Nerterogeomys Pocket GophersRegional Pleistocene distribution of Geomys (Neterogeomys).

Synonyms. Geomys.

Hibbard (1967:119) noted that "The genus Nerterogeomys Gazin (1942) is considered to be of subgeneric rank for those species of Geomys that have the mental foramen ventral to the extremity of the masseteric crest."

Sites.

Late Blancan: La Union (Morgan and Lucas 2003).

Literature. Hibbard 1967; Morgan and Lucas 2003.

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Geomys (Nerterogeomys) anzensis—Anza Pocket GopherRegional Pleistocene distribution of Geomys anzensis.

Synonyms. Nerterogeomys anzensis.

Sites.

Irvingtonian: Anza-Borrego (Becker and White 1981).

Literature. Becker and White.

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Geomys arenarius/G. bursarius—Desert or Plains Pocket GopherRegional Pleistocene distribution of Geomys arenarius/bursarius.

Specimens of Geomys usually do not have morphological features preserved that would allow determination of species. On the basis of geography, the records listed here probably are of G. arenarius.

Sites.

Mid Wisconsin: Pendejo Cave (Harris 2003).

Late Wisconsin: Navar Ranch (Van Devender et al. 1987: as G. bursarius); Tank Trap Wash (Van Devender et al. 1987: as G. bursarius).

Literature. Harris 2003; Van Devender et al. 1987.

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Geomys bursarius (Shaw 1800)—Plains Pocket GopherRegional Pleistocene distribution of Geomys bursarius.

Synonyms. Geomys parvidens.

Sites.

Records given here as assumed to be G. bursarius since they are outside of the current distribution of G. arenarius. However, Jal is within the current range of G. knoxjonesi.

Pleistocene: Perico Creek (Morgan and Lucas 2005).

Rancholabrean: Jal (Morgan and Lucas 2005).

Late Wisconsin: Blackwater Loc. No. 1 (Slaughter 1975: cf.); Tramperos Creek (Morgan and Lucas 2005).

Literature. Morgan and Lucas 2005; Slaughter 1975.

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Geomys (Nerterogeomys) garbanii (White and Downs 1961)—Garban's Pocket GopherRegional Pleistocene distribution of Geomys garbanii.

Synonyms. Nerterogeomys garbanii.

White and Downs (1961) named this species from the Vallecito Creek fauna. Their diagnosis was of a large size, about the size of a large Geomys bursarius or G. personatus, with a deeper rostrum, and with the tympanic bullae and external auditory meatus larger than in any other species.

Presence of a large sample allowed White and Downs (1961) to investigate intraspecific variation. Notably, they found (p. 12) that the position of the mandibular mental foramen varied "from a position ventral to P4, and the extension of the anterior masseteric scar to a position anterior to these structures." It is largely the position of this foramen anterior to the masseteric scar that has been used to diagnose the genus Nerterogeomys.

Sites.

Irvingtonian: Anza-Borrego (Becker and White 1981).

Literature. Becker and White.

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Geomys (Nerterogeomys) minor Gidley 1922 —Small Pocket GopherRegional Pleistocene distribution of Geomys (Nerterogeomys)minor

Synonyms. Nerterogeomys minor.

Gidley (1922) described the species as below:

Type.-Portion of a right lower jaw lacking the last molar (catalog No. 10494, US Nat. Mus.).

Paratype. A right upper incisor (catalog No. 10534, U.S. Nat. Mus.).

Locality.-Both from the Benson locality.

Description.-Length of cheek-tooth (estimated) 5.4 millimeters; the jaw is slightly smaller than that of G. parvidens and differs from it otherwise in having the anterior masseteric area more depressed, the submental foramen slightly farther back in position, cheek teeth relatively larger, and the anterior lobe of p4 more nearly circular in outline; no anterior fossa between cheek teeth and coronoid process.

An associated upper incisor tooth is of appropriate size for the species. It shows the characteristic grooving of a true Geomys, and it is this fact which has determined the generic reference of G. minor.

Sites.

Late Blancan: California Wash (Johnson et al. 1975).

Literature. Johnson et al. 1975.

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Geomys (Nerterogeomys) paenebursarius Strain 1966 —Early Plains GopherRegional Pleistocene distribution of Geomys paenebursarius.

Synonyms. Nerterogeomys paenebursarius.

This pocket gopher is similar to the living Geomys bursarius, differing primarily in the position of the mental foramen (Strain 1966).

Sites.

Late Blancan: Caballo (Morgan et al. 2011: ?).

Literature: Morgan et al. 2011; Strain 1966.

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Geomys (Nerterogeomys) persimilis (Hay 1927)—Hay's Pocket GopherRegional Pleistocene distribution of Geomys persimilis.

Synonyms. Nerterogeomys persimilis.

Sites.

Late Blancan: 111 Ranch (Morgan and White 2005: ?); California Wash (Morgan and White 2005); Curtis Ranch (Morgan and White 2005); San Simon Fauna (Morgan and White 2005: ?).

Literature. Morgan and White 2005

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Last Update: 7 Jul 2014