An iconic member of the Ediacara Biota, Dickinsonia Sprigg is one of few such taxa with multiple species. Here we use Gaussian finite mixture models to assess the validity of species distinctions for this genus. Our results indicate that the five described species of Dickinsonia from the Ediacara Member, South Australia are better classified as two based on multiple approaches. Two different methods for dimension reduction both provide strong support for two groups, with overlapping but distinct mixture models. The variable selection method produces the most biologically realistic clusters, indicating that the two species can be primarily differentiated based on the greater relative size of the anterior most unit of Dickinsonia costata Sprigg compared with Dickinsonia tenuis Glaessner & Wade. Despite differences in aspect ratio and number of modules, both species regulated growth to maintain overall shape. The greater likelihood of preservation of a midline and an irregular outer margin in D. tenuis highlights differential structural integrity and flexibility. Co-occurrence in the Ediacara Member indicates that both species occupied the same environments and temporal distribution. Smaller maximum and average size for D. costata, combined with higher abundance, may suggest a comparatively shorter lifespan and increased rates of reproduction.

中文翻译：

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来自南澳大利亚埃迪卡拉纪的 Dickinsonia Sprigg 种

Dickinsonia Sprigg 是埃迪卡拉生物群的标志性成员，是少数具有多个物种的分类群之一。在这里，我们使用高斯有限混合模型来评估该属物种区分的有效性。我们的结果表明，基于多种方法，南澳大利亚埃迪卡拉成员的五种狄更逊水母被更好地归类为两种。两种不同的降维方法都为两组提供了强有力的支持，具有重叠但不同的混合模型。变量选择方法产生了最具生物学真实性的聚类，表明这两个物种可以根据Dickinsonia costata Sprigg 的最前部单元的相对大小与Dickinsonia tenuis Glaessner & Wade。尽管纵横比和模块数量存在差异，但两个物种都通过调节生长来保持整体形状。D中保留中线和不规则外缘的可能性更大。 tenuis突出了不同的结构完整性和灵活性。埃迪卡拉成员的共同出现表明这两个物种占据相同的环境和时间分布。D的最大尺寸和平均尺寸更小。 costata与更高的丰度相结合，可能意味着相对较短的寿命和更高的繁殖率。