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Figure 1. Compilation of temporally associated significant events and records during the Neoproterozoic–Paleozoic transition. From bottom to top: (i) fossil GSA TODAY | www.geosociety.org/gsatoday
(yellow bars—first appearance) and molecular (black bars—reported divergence estimates; Erwin et al., 2011) records superimposed on the Cambrian and
Paleozoic faunas of Sepkoski (1981); (ii) ecological record (green bars) indicating first appearances of important behaviors/events overlain on gray rectangles
comprising the Eltonian pyramid and diagrammed after megatrajectories of Knoll and Bambach (2000); and (iii) environmental record of major Earth system
events (light blue bars—Snowball Earth glaciations; maroon bars­—orogenies and other events), with ocean-atmosphere oxygenation data (blue-gray, Sperling
et al., 2015), �Nd (light gray, Keto and Jacobson, 1988) and 87Sr/86Sr estimates (mid-gray, Maloof et al., 2010), and the �13C record (dark gray, Saltzman and
Thomas, 2012). The Cambrian Explosion is indicated by the yellow-orange column, and the temporal expanse of the wormworld fauna by the green column.
GICE—Guttenberg Carbon Isotope Excursion; GOBE—Great Ordovician Biodiversification Event; HICE—Hirnantian Carbon Isotope Excursion; PDA
—protostome-deuterostome ancestor; SPICE—Steptoean Positive Carbon Isotope Excursion.

functioned. For instance, vertical tiering in fossil communities at waste organics to the substrate, providing a direct link between
Mistaken Point, Canada, highlights the importance of competi- pelagic and benthic ecosystems. Nonetheless, while some
tive nutrient acquisition from the seawater (Clapham and Ediacaran taxa may have gained nutrients through suspension
Narbonne, 2002; Ghisalberti et al., 2014). Filter feeding was likely feeding (Rahman et al., 2015), osmotrophy (Laflamme et al.,
well established, as evidenced by putative Cryogenian sponges 2009), or saprotrophy (the latter two of which are rare to absent in
(Maloof et al., 2010, though see Antcliffe et al., 2014) and less extant Metazoa; Sperling and Vinther, 2010), the feeding strate-
contested Ediacaran sponges (Yin et al., 2015)—which, along with gies of most Ediacaran taxa remain indeterminate due to the
the evolution of zooplankton (Butterfield, 1997), served to deliver abundance of non-analogue body plans. It is likely, though, that

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