The Franklin Mountains are located in the extreme western tip of Texas and extend northward into south-central New Mexico, approximately 23 mi (37 km) from El Paso which is built around the southern end of the range.

The outcrops of Permian strata in the Franklin Mountains consist of small outliers on the western edge which are separated from the main range. The Permian is represented by the Hueco Group (Wolfcampian) which is divided into three formations, in ascending order: the Hueco Canyon, Cerro Alto, and Alacran Mountain Formations.

The 1,350-ft (411.5 m) thick Hueco Canyon Formation contains 22 genera and 23 species of brachiopods. These are Orthotichia sp., Accosarina sp., Acritosia silicica Cooper & Grant, Rhipidomella hessensis R. E. King, Derbyia sp., Chonetinella sp., Kozlowskia capaci (d'Orbigny), Reticulatia huecoensis (R. E. King), Dasyaria undulata Cooper & Grant, Dasyaria wolfcampensis (R. E. King), Cancrinella parva Cooper & Grant, Linoproductus cora (d'Orbigny), Pontisia franklinensis Cooper & Grant, Stenocisma sp., Hustedia huecoensis R. E. King, Rhynchopora sp., Crurithyris tumbilis Cooper & Grant, Cleiothyridina rectimarginata Cooper & Grant, Composita cracens Cooper & Grant, Beecheria bovidens (Morton), Chondronia obesa Cooper & Grant, Dielasma sp. 1, and Dielasma p. 2.

The 350 to 425-ft (106.7 to 129.5 m) thick Cerro Alto Formation contains 8 genera and 9 species of brachiopods. These are Derbyia sp., Chonetinella sp., Squamaria moorei Muir-Wood & Cooper, Cancrinella altissimia R. H. King, Linoproductus cora (d'Orbigny), Pontisia franklinensis Cooper & Grant, Crurithyris quadalupensis (Girty), Composita cracens Cooper & Grant, and Composita mexicana (Hall).

The 315 to 739-ft (96 to 225.2 m) thick Alacran Mountain Formation contains 24 genera and 27 species of brachiopods. These are Crania modesta White & St. John, Meekela sp., Enteletes sp., Derbyia sp., Pseudoleptodus sp., Micraphelia sp., Costellarina costellata (Muir-Wood & Cooper), Hystriculina convexa Cooper & Grant, Kutorginella sp., Nudauris sp., Kozlowskia capaci (d'Orbigny), Dasysaria undulata Cooper & Grant, Dasysaria wolfcampensis (R. E. King), Linoproductus sp., Pontisia franklinensis Cooper & Grant, Stenocisma hueconians (Girty), Hustedia hessensis R. E. King, Hustedia huecoensis R. E. King, Crurithyris sp., Neophricadothyris sp., Composita cracens Cooper & Grant, Composita mexicana (Hall), Reticulariina heuconiana Cooper & Grant, Gypospirifer nel oni Cooper & Grant, Beecheria bovidens (Morton), Chondronia obesa Cooper & Grant, Dielasma sp.

Other faunal taxons present in the Hueco Group of the Franklin Mountains include Foraminifera, Fusulinida, Porifera, Coelenterata, Bryozoa, Polyplacophora, Gastropoda, Cephalopoda, Bivalvia, Scaphopoda, Crustacea, Trilobita, Annelida, Crinoidea, Echinoidea, Conodonta, and Vertebrata.

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