Department of Geosciences, Princeton University, Princeton, NJ 08544;
Neukom Institute, Dartmouth College, Hanover, NH 03755.
Proc Natl Acad Sci U S A. 2020 Aug 18;117(33):19760-19766. doi: 10.1073/pnas.2009129117. Epub 2020 Aug 3.
Strata from the Ediacaran Period (635 million to 538 million years ago [Ma]) contain several examples of enigmatic, putative shell-building metazoan fossils. These fossils may provide insight into the evolution and environmental impact of biomineralization on Earth, especially if their biological affinities and modern analogs can be identified. Recently, apparent morphological similarities with extant coralline demosponges have been used to assign a poriferan affinity to , a modular encrusting construction that is found growing between (and on) microbial buildups in Namibia. Here, we present three-dimensional reconstructions of that we use to assess the organism's proposed affinity. Our morphological analyses, which comprise quantitative measurements of thickness, spacing, and connectivity, reveal that produced approximately millimeter-thick meandering and branching/merging sheets. We evaluate this reconstructed morphology in the context of poriferan biology and determine that likely is not a sponge-grade organism.
埃迪卡拉纪地层(6.35 亿至 5.38 亿年前)中包含了几个神秘的、假定的壳状后生动物化石的例子。这些化石可能为生物矿化对地球的进化和环境影响提供了一些见解,特别是如果能够确定它们的生物亲缘关系和现代类似物。最近,与现存珊瑚状有孔虫的明显形态相似性被用来将一种模块化的覆盖结构(在纳米比亚,这种结构生长在微生物堆积物之间(和之上))指定为多孔动物的亲缘关系。在这里,我们展示了我们用来评估该生物假定亲缘关系的三维重建。我们的形态分析包括对厚度、间距和连通性的定量测量,结果表明产生了大约毫米厚的蜿蜒和分支/合并的薄片。我们根据多孔动物生物学评估了这种重建的形态,并确定可能不是海绵级的生物。