886 Materials and methods


The material described in this report derives from nine sections covering the Montezuman–Delamaran interval (Terreneuvian/ Cambrian Stage 2–Cambrian Series 3/Cambrian Stage 5) of the different shelf facies realms (Figs. 1–4). All carbonate samples are characterized by a high fossil content observable in thin sections or even macroscopically. However, the major part of small shelly fossils is preserved as carbonate, which hampers extraction from the limestone. Several preparation methods were tested using 95% to pure acetic acid partly in combination with copper(II) sulfate and chloroform (see Nötzold, 1965; Knitter, 1979; Tarsilli and Warne, 1997). All these methods require a distinct porosity of the limestone that enables the intrusion of chemicals and thus the expansion of the rock due to gassing or crystallization. But, the Laurentian samples are strongly lithified without any porosity, which inhibited extrac- tion of microfossils using these procedures. The best results were realized by dissolving the carbonate samples in buffered 7% acetic acid. The extracted microfossils are often corroded during the chemical preparation, but it seems to be the only way for releasing a significant number of small shelly fossils from the Laurentian samples. However, due to dissolution of a majority of the carbonate fossils, this procedure delivered only few phosphatic internal molds and silicified specimens out of the total fossil content. Acetic residues were sieved, dried, and the faunal elements were hand-picked from the residue under a binocular microscope. Subsequently, they were mounted, sputter-coated with gold, and photographed under a CamScan 44 scanning electron microscope at the Department of Geology of the University of Cologne.


Repositories and institutional abbreviations.—The material described and figured is housed in the collection of the Geolo- gical Institute of the TU Bergakademie Freiberg under the prefix FG 544/GB/locality/sample/SEM-stub number. For brevity herein, localities and specimens are cited without the prefixFG 544/GB. Localities are listed asAC(Antelope Canyon), E (Echo Canyon), GR (Groom Range), GS (Grassy Spring), I (Indian Springs Canyon), LC (Log Cabin Mine), M (Montezuma Range), OS (Oak Spring Summit), and SM (Split Mountain) (Figs. 1–4). Individual collections are denoted by locality abbreviation and sample number (e.g., SM 14).


Systematic paleontology


The helcionelloid molluscs, Anabarella chelata and Costipela- giella nevadense, were verified from the lowermost Emigrant Formation of the Split Mountain section (SM 14,SM15; Fig. 3). Stratigraphic position and locality are identical with those published by Skovsted (2006a). Thus, these species are figured (Fig. 5.1–5.16), but not discussed herein.


Phylum Mollusca Cuvier, 1797 Class Helcionelloida Peel, 1991 Order Helcionellida Geyer, 1994


Family Helcionellidae Wenz, 1938 Genus Pelagiella Matthew, 1895


Journal of Paleontology 91(5):883–901


Type species.—Cyrtolithes atlantoides Matthew, 1894; lower Cambrian of southeast New Brunswick, Canada.


Pelagiella aff. P. subangulata (Tate, 1892) Figures 5.17–5.22, 6.1–6.23, 7.1–7.6, 8.35–8.37


1892 Ophileta subangulata Tate, p. 184, pl. 2, fig. 8a–b. 1984 Pelagiella emeishanensis He in Xing et al., p. 167, pl. 13, figs. 1–5.


1986 Pelagiella sp.; Laurie, p. 447, fig. 10D–E. 1990 Pelagiella subangulata; Runnegar in Bengtson et al., p. 254, figs. 167, 168A–D, 169A–F, H–L.


1994 Pelagiella emeishanensis; Elicki, p. 71, fig. 4.8. 1994 Pelagiella lorenzi Kobayashi, 1939; Elicki, p. 71, fig. 4.6, 4.7.


1996 ?Pelagiella sp.; Elicki, p. 156, pl. 8, figs. 5–8. 2001 Pelagiella subangulata; Parkhaev in Gravestock et al., p. 193, pl. 44, figs. 1–14, pl. 45, figs. 1–10.


2002 Pelagiella subangulata; Elicki, p. 23, pl. 1, figs. 1–18. 2003 Pelagiella subangulata; Elicki, p. 57, pl. 2, fig. 1. 2003 Pelagiella subangulata; Elicki, Hamann, and Münzberger, p. 33, pl. 5, figs. 3, 4.


1996 Pelagiella emeishanensis; Elicki, p. 155, pl. 7, figs. 6, 7. 1996 Pelagiella lorenzi; Elicki, p. 154, pl. 7, figs. 1–5. 1996 ?Pelagiella aff. adunca He and Pei in He, Pei, and Fu; Elicki, p. 155, pl. 8, figs. 1–4.


2004 Pelagiella subangulata; Skovsted, p. 30, pl. 8, figs. a, b. 2006 Pelagiella subangulata; Wotte, p. 151, fig. 5.n–5.p. 2007 Pelagiella subangulata; Steiner et al., p. 83, fig. 7I, 7J.


2014 Pelagiella subangulata; Parkhaev, p. 374, pl. 3, figs. 5, 6.


2016 Pelagiella subangulata; Betts et al., p. 183, fig. 18A–18H.


Holotype.—Ophileta subangulata Tate, 1892 (p. 184, pl. 2, fig. 8a, 8b); “Cambrian limestone at Parara, near Ardrossan,” South Australia.


Occurrence.—About one hundred internal molds from the Grassy Spring (GS 13), Groom Range (GR 11), Log Cabin Mine (LC 6), Oak Spring Summit (OS 5), and Split Mountain (SM 14) sections; Dyeran Stage. Three internal molds from the Montezuma Range section (M 5); basal Montezuman Stage.


Description.—Small univalve internal molds up to 1mm long and 0.4mm high. Turbospiral and dextrally coiled with 1–1.5 rapidly expanding whorls. Last whorl wide; cross section irre- gular oval/trapezoidal to sub-triangular. Aperture often broken. Near convex right side of the apertural margin the residual of a projecting ear. Spire slightly submerged culminates in a plane or slightly concave left flank. Protoconch often hook-shaped. Surfaces of the molds without ornamentation.


Remarks.—Due to strong corrosion and lack of the aperture in any of the specimens, an affiliation to a definite species of Pelagiella Matthew, 1895 or Costipelagiella Horný, 1964 is difficult. Pelagiella is characterized by a high morphological variation, resulting in a multitude of nominated species, often with unclear differences. Even within a species, variation in


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