Pelagiella sp.

Skovsted, Christian B. & Peel, John S., 2007, Small shelly fossils from the argillaceous facies of the Lower Cambrian Forteau Formation of western Newfoundland, Acta Palaeontologica Polonica 52 (4), pp. 729-748 : 737

Pelagiella sp.

Fig. 4I, J.

Type species: Cyrtolithes atlantoides Matthew, 1894 .

Material.—NFM−690, NFM−691, and thousands of specimens from samples ICS 1421, ICS 1518, ICS 1519, and JSP1982−01.

Description.—Asymmetrically coiled (through about 1–2 whorls) and rapidly expanding conch with a low spire that projects only slightly above the margin of the aperture (in apertural view). Aperture elongated oval with greatest elongation offset from the axis of coiling by approximately 70 °. A distinct longitudinal furrow is present on the dorsal surface of internal moulds, and a second furrow is deeply embedded on the ventral surface, just under the spire ( Fig. 4I 3 ). Neither furrow extends all the way to the aperture. A partial external mould of a specimen that was apparently lodged in the aperture of a larger individual ( Fig. 4J 1 ), preserves an ornamentation of fine, aperturally arched ridges on the dorsal surface ( Fig. 4J 2 ).

Discussion.—Internal moulds of the widespread genus Pelagiella Matthew, 1895 are extremely numerous in the acid residues from western Newfoundland. The generalised morphology of these specimens is shared by a host of species of Pelagiella from the Lower and Middle Cambrian across the world (see review by Parkhaev in Gravestock et al. 2001), and without detailed information on external shell characters any specific determination is difficult. Only two species of Pelagiella have been described from Lower Cambrian rocks of eastern Laurentia, P. primaea (Billings, 1872) from the Taconic Allochthon of New York, Vermont and Quebec ( Lochman 1956; Landing et al. 2002) and P. subangulata (Tate, 1892) from North−East Greenland (Skovsted 2004). The specimens from western Newfoundland appear to differ from P. subangulata by the slight projection of the spire above the apertural margin in larger (adult?) specimens, but the morphology of P. primaea is too poorly known to allow meaningful comparison. The Newfoundland specimens are thus left in open nomenclature.

Figures

Fig. 3. Trilobites, echinoderms, and sponges from the Lower Cambrian, Forteau Formation (Western Newfoundland). A. Dorypygidae indet., internal mould of fragmentary cephalon, NFM−671 from ICS 1421; in dorsal (A1) and left lateral (A2) views. B. Calodiscus lobatus (Hall, 1847), NFM−672, dorsal view of silicified cephalon. C. Ptychoparioid indet., NFM−673 from ICS 1421, silicified cephalon. D. Olenellid indet., NFM−674 from ICS 1421, dorsal view of silicified juvenile cephalon. E–J. Phosphatised echinoderm ossicles. E. Morphotype 1, NFM−675, dorsal view. F. Morphotype 1, NFM−676, dorsal view. G. Morphotype 1, NFM−677, ventral view. H. Morphotype 2, NFM−678, ventral view. I. Morphotype 2, NFM−679, dorsal view. J. Morphotype 2, NFM−680, oblique lateral view. K. Hexactinellid spicule, NFM−681, scale bar 100 ̊m. All specimens from JSP 1982−01 unless otherwise stated. All scale bars except K 500 ̊m.

Fig. 1. Lower Cambrian localities in eastern Laurentia (A), map of Newfoundland indicating the Bonne Bay region (B) and simplified Lower Cambrian stratigraphy in western Newfoundland (C).

Fig. 2. Brachiopods from the Lower Cambrian, Forteau Formation (Western Newfoundland). A, B. Eoobolus priscus (Poulsen, 1932). A. NFM−662, exterior view of incomplete ventral valve. B. NFM−663, ventral valve interior with pseudointerarea. C. Ventral valve of Eothele sp., NFM−664 from ICS 1421. D, E. Acrotretid indet. D. NFM−665, ventral valve exterior. E. NFM−666, dorsal valve exterior. F, G. Micromitra bella (Billings, 1872). F. NFM−667, ventral valve interior. G. NFM−668, dorsal valve interior. H, I. Obolella crassa (Hall, 1847). H. NFM−669, fragmentary ventral valve interior. I. NFM−670, fragmentary dorsal valve interior. All specimens from JSP 1982−01 unless otherwise stated. Scale bars 500 ̊m.