Freeman et al.—Upper Cambrian linguliform Brachiopods from Texas
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Figure 2. Stratigraphic ranges of linguliform brachiopods in the Threadgill Creek/Lange Range composite section, Gillespie County, Texas. Conodont and trilobite zonation after Loch and Taylor (2011) and Miller et al. (2012). Tic marks indicate sampled horizons that yielded brachiopods. The two sections are correlated at the base of the Cordylodus intermedius Zone, at 445m above the base of the Threadgill Creek section and 34.1m above the base of the Lange Ranch Section. Gray shaded ‘critical interval’ is Stage 4 of Stitt’s (1971b) and Stage 1 of Palmer’s (1979) interpretations of the biomere concept. Clav.=Clavohamulus hintzei conodont Subzone; Hir.=Hirsutodontus simplex conodont Subzone; and Fryx.=Fryellodontus inornatus conodont Subzone.
later expanded by Barnes and Bell (1977). The faunas of these strata have been the subject of numerous investigations particularly focusing on trilobite and conodont biostratigraphy (Bell and Ellinwood, 1962; Winston and Nicholls, 1967; Longacre, 1970; Miller et al., 1982; Stitt and Miller, 1987; Miller and Stitt, 1995; Stitt andMetcalf, 1995; Miller et al., 2003, 2012; Loch and Taylor, 2011). Other papers (Miller et al., 2003; Bassett et al., 2007) document the chemostratigraphy and sequence stratigraphy of the strata as well. The sample numbering system (Fig. 2 and Supplemental
Data Tables 1, 2) is complex due to a measurement error. The Threadgill Creek section was measured in feet (Bridge et al., 1947) and the zero-foot mark of the composite section (Barnes and Bell, 1977) was placed at the Precambrian/Cambrian contact. Measurement along Threadgill Creek ended at 1460 ft (445 m) at a lithologic change thought to be the contact between the Wilberns and Tanyard formations; overlying strata are poorly exposed. Measurement was offset to what is now called the Lange Ranch section (Fig. 2), and the footage ‘1460’ was painted at the Wilberns/Tanyard contact. Later, J.F. Miller discovered ~63 ft (~19 m) of strata missed in making the offset (Barnes and Bell, 1977). These strata and strata exposed below are assigned to the uppermost Wilberns For- mation and were numbered 1–175 ft, with LR-175 (top of Wilberns Formation) equivalent to LR-1460 (base of Tanyard Formation in Barnes’ original section), and LR-112 equivalent to TC-1460 in the original section. The Tanyard Formation exposed in the Lange Ranch section is measured upward
yielded insoluble residue containing 813 identifiable brachiopod valves from 41 stratigraphic levels. Examination and imaging of specimens utilized Hitachi 4800, Hitachi S3400N, and JEOL JSM-6010 scanning electron microscopes (SEM).
continuing from LR-1460 following paint marks made by V.E. Barnes. Bulk samples of 2–5 kg dissolved in 10% acetic acid
Repositories and institutional abbreviations.—Specimens are reposited with the University of Texas-Austin Non-Vertebrate Paleontology Laboratory (NPL). Abbreviations used for type specimen repositories are as follows: Central Scientific Research Geological Exploration Museum, St. Petersburg (CNIGR), and United States National Museum (USNM).
Systematic paleontology
Classification is after Holmer and Popov (2000), with exceptions noted.
Subphylum Linguliforma Williams et al., 1996 Class Lingulata Gorjansky and Popov, 1985 Order Lingulida Waagen, 1885
Superfamily Linguloidea Menke, 1828 Family Obolidae King, 1846 Subfamily Obolinae King, 1846
Genus Lingulella Salter, 1866
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