Data from: The Proterozoic record of eukaryotes

Proterozoic strata host evidence of global “Snowball Earth” glaciations, large perturbations to the carbon cycle, proposed changes in the redox state of oceans, the diversification of microscopic eukaryotes, and the rise of metazoans. Over the past half century, the number of fossils described from Proterozoic rocks has increased exponentially. These discoveries have occurred alongside an increased understanding of the Proterozoic Earth system and the geological context of fossil occurrences, including improved age constraints. However, the evaluation of relationships between Proterozoic environmental change and fossil diversity has been hampered by several factors, particularly lithological and taphonomic biases. Here we compile and analyze the current record of eukaryotic fossils in Proterozoic strata to assess the effect of biases and better constrain diversity through time. Our results show that mean within assemblage diversity increases through the Proterozoic Eon due to an increase in high diversity assemblages, and that this trend is robust to various external factors including lithology and paleogeographic location. In addition, assemblage composition changes dramatically through time. Most notably, robust recalcitrant taxa appear in the early Neoproterozoic Era, only to disappear by the beginning of the Ediacaran Period. Within assemblage diversity is significantly lower in the Cryogenian Period than in the preceding and following intervals, but the short duration of the nonglacial interlude and unusual depositional conditions may present additional biases. In general, large scale patterns of diversity are robust while smaller scale patterns are difficult to discern through the lens of lithological, taphonomic, and geographic variability.

元古宙（Proterozoic）地层中保存有全球“雪球地球（Snowball Earth）”冰期、碳循环剧烈扰动、海洋氧化还原状态变化假说、微观真核生物演化分异以及后生动物兴起的相关证据。过去半个世纪以来，元古宙岩石中被描述的化石数量呈指数级增长。这些发现与学界对元古宙地球系统以及化石产出地质背景（包括更为精准的年代约束）的认知深化同步推进。然而，评估元古宙环境变化与化石多样性之间的关联时，仍受到多种因素阻碍，尤以岩性偏差与埋藏学（taphonomic）偏差最为突出。本研究整合并分析当前元古宙地层中的真核化石记录，以评估偏差的影响，并更为精准地限定不同时期的多样性变化轨迹。研究结果显示，元古宙时期的群落内平均多样性随时间推移不断提升，这一现象源于高多样性群落占比的增加，且该趋势不受岩性、古地理位置等多种外部因素的干扰，具有稳健性。此外，群落组成随时间发生显著变化。尤为值得注意的是，稳定性较强的难降解类群在新元古代早期出现，但在埃迪卡拉纪（Ediacaran Period）初期便已消失。成冰纪（Cryogenian Period）时期的群落内平均多样性显著低于前后两个时期，但非冰期幕的持续时间较短以及特殊的沉积条件，可能带来额外的偏差。总体而言，大尺度的多样性变化模式具有稳健性，而小尺度的多样性变化模式则难以通过岩性、埋藏学以及地理变异的视角加以甄别。