578


BOAG ET AL.


(Table 2; Baselga and Orme, 2012). Jaccard dissimilarity is a well-known ecological metric that has frequently been used in paleocological studies to quantify taxonomic dissimilarity (e.g., Hammer and Harper 2006), while Simp- son’s beta represents turnover independent of nestedness (Baselga 2010) and is robust to gradients in richness (Koleff et al. 2003; Darroch and Wagner 2015). All analyses were performed using the open-source statistical


TABLE 2. Convex hulls treated as single “community,” in which presence/absence of each genus is summed from all fossil occurrences into each category. Beta diversity is calculated for overall dissimilarity (0=complete similarity, 1=complete dissimilarity) between categories, using Jaccard pairwise dissimilarity, and Simpson and Sorenson multisite indices.


Assemblage Depth index Lithology Time index


Jaccard 0.952


0.918 0.905 0.836


Multisite Simpson


0.811 0.726 0.711 0.630


Multisite Sorenson


0.908 0.883 0.842 0.766


software package R, package Vegan, Version 2.3-0 (Oksanen et al. 2015;RDevelopment Core Team 2015).


Retesting the Assemblage Concept Aprincipal goal of this study was to reassess


the validity of three Ediacaran assemblages based on taxonomic distinctness as identified in Waggoner (2003). We therefore selected the original 21 localities (and respective assem- blage designations) identified in Waggoner (2003) and applied these as polygons over the updated taxonomic ordination space. The results show that even after a significantly updated data set (86 localities, 124 genera), the original 21 localities and their resulting three assemblages still provide clear taxonomic separation at CI=95% (Fig. 1, Supplementary Table S.4.A). Furthermore, assemblage polygons produced the greatest dissimilarities in beta-diversity values among all tested variables (Table 2), demonstrating strong


FIGURE 1. Ediacaran taxonomic ordination plot based on the updated data set (86 localities, 124 genera). The original 21 localities identified in Waggoner (2003) have been color assigned to their respective “Avalon,”“White Sea,” and “Nama” designations. These have then been coded as polygons to assess the degree to which they remain as discrete taxonomic assemblages against an updated ordination space.


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