Images of the Hellefjord fossils.

<p>Left: photograph of discoidal fossils and sinusoidal tube casts, Hellefjord Schist. Right: sketch of salient features of fossils. Inset: photogrammetric surface reconstruction with radiance scaling shader. Planes A-A’ and B-B’ reflect eastward looking tilted section through discoids.</p

Examples of preservation styles found in Ediacaran (and one early Cambrian) sites compared to fossils from Sørøy, northern Norway.

<p>A: Cluster of flat-convex discs from Newfoundland [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref084" target="_blank">84</a>]; note similarity in contact between discs and those in B. B: Southern Sørøy discs of varying size [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref055" target="_blank">55</a>]. C: <i>Primocandelabrum</i> from Newfoundland showing holdfast and branching stem which may have shared some similar morphological elements to the Hellefjord Schist forms. D: Disc feature from Digermul Peninsula, Norway [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref019" target="_blank">19</a>]. Note similarity of central boss to E. E. Discs and tube cast (stem) from Hellefjord Schist Sørøy—see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.g002" target="_blank">Fig 2</a>. F: Small discs (Type morph of <i>Aspidella</i>) showing central invagination with recessed bosses [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref084" target="_blank">84</a>] note similarity to areas on B. G: Early Cambrian fossil from California, previously compared to discs of Ediacaran age, highlighted region with “burrow” abutting disc [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref020" target="_blank">20</a>] note similarity to E. H: Positive rimmed disc impressions associated with <i>Aspidella</i>, Newfoundland [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref083" target="_blank">83</a>], note similar edge morphology to E. Scale bars are 1 cm.</p

Locality and stratigraphy of the fossils.

<p>Geological map of the Langstrand—Hellefjord area, Sørøy (modified after [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref021" target="_blank">21</a>]). Fossil locality indicated by star. Inset left: main tectonic units of Finnmark with overview map of Norway. Inset right: simplified tectonostratigraphy of KNC and overlying Hellefjord Schist.</p

Boss area versus disc area with linear regression fits to all data and by geographic location.

<p>The adjusted R² value is shown as a percentage for each fit and indicates the degree of scatter accounted for by the regression. Upper plot shows 0–2000 and 0–200 mm² region only. Lower plot is enlargement of dashed region (Newfoundland data from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164071#pone.0164071.ref108" target="_blank">108</a>]). − = negative epirelief; + = positive epirelief.</p

Inverse concordia diagrams for zircon grains analysed by SIMS.

<p>CK011 and CK004 are detrital material. The age of the youngest analysis is shown. CK231 is interpreted to reflect both inheritance and a magmatic population. U—Pb data are plotted as 2 σ error crosses.</p