Echinodermata Klein, 1734

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 : 733-734

Phylum Echinodermata Klein, 1734

Discussion.—Echinoderm ossicles of varying morphology are present in all samples. The echinoderm affinity of these fossils is demonstrated by the preserved stereome ultrastructure. The composite construction of echinoderm skeletons usually precludes identification of individual taxa based only on disarticulated material but two ossicle types among the forms present in Newfoundland are sufficiently distinct to warrant individual description. Less distinct, circular, oval or irregular ossicles also occur together with the two types described below.

Morphotype 1: This type of sclerite is represented by triangular to sub−circular concavo−convex ossicles with variously indented margins ( Fig. 3E–G ). These sclerites are reminiscent of star−shaped sclerites of eocrinoids (compare Fig. 3E–F to pl. 1 of Ubaghs and Vizcaïno 1990).

Morphotype 2: The second type of sclerite is represented by circular to oval, pyramidal ossicles with the upper (convex) surface ornamented by small depressions or undulating ridges and the lower (variously concave, convex or flat) surface with larger, irregular depressions divided by narrow ridges ( Fig. 3H–J ). Morphologically identical ossicles were recently described from the Bastion and Ella Island Formation of North−East Greenland ( Skovsted 2006a: fig. 7.14–15) and may have potential for regional correlation .

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.