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Journal of Paleontology 92(1):80–86
Figure 1. Eldonioid from the early Cambrian Emu Bay Shale, Kangaroo Island, South Australia, SAM P45196; previously illustrated by Paterson et al. (2016, fig. 6g). (1) Near complete specimen; lighting from top left. (2) Image taken with very low-angled light from top right to show surface relief and other features
such as the associated traces (burrow [white arrows]; circular indentations [yellow arrows]; tubercular protuberance [green arrow]) and the bulge of the coiled sac near the center (black arrows). (3) Close-up showing detail of concentric corrugations; lighting from bottom right. (4) Close-up showing detail of internal lobes, including primary bifurcation (black arrow) and secondary bifurcations (white arrows); lighting from bottom right. (1, 2) Scale bar=5mm; (3) scale bar=3mm; (4) scale bar=2mm.
Materials and methods
Specimens were collected from the lower Cambrian (Series 2, Stage 4) Emu Bay Shale Konservat-Lagerstätte at Buck Quarry, BigGully,Kangaroo Island, SouthAustralia (for detailed locality information, see Gehling et al., 2011; Paterson et al., 2016). Photographs were taken with a Canon EOS 5D digital SLR
camera with a CanonMP-E 65mm1–5x macro lens, using low- angled light from different directions to enhance the morpho- logical detail of the fossils.
Repository and institutional abbreviation.—Two specimens, SAM P45196 and P46361, are reposited in the South Australian
Museum paleontology (SAM P) collection in Adelaide, South Australia.
Description
The specimens represent two incomplete, but clearly subcircular, nonbiomineralized discs. SAMP45196 (Fig. 1) has a diameter of 20.9mm; SAMP46361 (Fig. 2) is too incomplete to be measured, but is of a similar size. Neither specimen shows evidence of a mouth, tentacles, or anus, which are located on the interpreted ventral side of other eldonioids. Consequently, we interpret the exposed surface of the EBS specimens as representing the dorsal disc, though its orientation in life is not certain.
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