Archiasterella 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 : 741

Archiasterella sp.

Fig. 6C, D .

Type species: Archiasterella pentactina Sdzuy, 1969 .

Material.—NFM−709, NFM−710, and 10 additional specimens from samples ICS 1421, ICS 1519, and JSP1982−01.

Discussion.—Sclerites with four marginal rays only (4+0), three of which lie in the plane of the basal facet, while the fourth ray curves strongly away (by at least 60 °) from this plane. The basal facet has tightly set and relatively large basal foramina. The recurved sagital ray of these chancelloriid sclerites suggests affinity to Archiasterella Sdzuy, 1969 . Several species of Archiasterella have been proposed based only on the number of rays, and Vassiljeva and Sayutina (1993) proposed A. tetraspina for sclerites of Archiasterella with a total of four rays. Given the variability in sclerite configuration and ray number which has been demonstrated to occur in the scleritomes of chancellorids ( Qian and Bengtson 1989; Janussen et al. 2002), including Archiasterella ( Randell et al. 2005) , we consider this practice to be unreliable. All specimens of Archiasterella from Newfoundland are fragmentary internal moulds and are thus left in open taxonomy.

Figures

Fig. 6. Problematic taxa from the Lower Cambrian, Forteau Formation (Western Newfoundland). A, B. Chancelloria sp. A. Phosphatic internal mould, NFM−707; B. Phosphatic internal mould viewed from basal facet, NFM−708. C, D. Archiasterella sp. C. NFM−709 from ICS 1421, phosphatic internal mould; C1, lateral view; C2, viewed from basal facet. D. NFM−710, oblique view of phosphatic internal mould. E, F. Hyolithellus sp. E. NFM−711. F. NFM−712. G. Lapworthella shodakensis (Lochman, 1956). NFM−713, dorso−ventrally flattened sclerite; in lateral (G1) and dorsal (G2) views. All specimens from JSP 1982−01 unless otherwise stated. Scale bars 200 ̊m.