Accumulated records of organic microfossils span billions of years of Earth history. The majority of this record consists of prokaryotes plus eukaryotes of a protistan grade, yet this type of fossilisation is also capable of capturing the organically preserved remains of animals. Recently, it has become apparent that non-biomineralizing animal groups, otherwise known only from rare instances of exceptional fossilisation, can preserve in this fashion. Given this high taphonomic fidelity combined with the temporal continuity of organic microfossil preservation, it is clear this style of fossilisation has the potential to circumvent some of the major biases that afflict the current early animal fossil record. Despite this, there have been no attempts to survey recorded instances of animal-derived organic microfossils. We constructed a global database comprising 394 studies of organic microfossils covering 399 sedimentary rock formations spanning the Tonian–Cambrian Stage 5/Wuliuan Stage (1 Ga to 505 Ma). The database consolidates scattered reports and provides a first appraisal for how a record of metazoans emerges within the broader archives of organic microfossils. Scrutiny of the current record reveals that organic microfossils contain the oldest body fossil evidence for a number of key metazoan clades, including the Chaetognatha, Annelida, Priapulida, ‘lobopods’ and Panarthropoda, Crustacea, Pterobranchia, and potentially even the Bilateria. Also detected among this record are the fossilised remains of poriferans, chancelloriids, palaeoscolecids, loriciferans, bradoriids, trilobites, wiwaxiids, molluscs, hyoliths, brachiopods and chordates. Our data shows that metazoan-derived remains are relatively common constituents of palynological preparations from sediments of a Cambrian age or younger. Such metazoan remains are also detected in organic microfossil assemblages from several formations of late Ediacaran age, but are entirely absent from the large number of equivalent preparations from older sediments, throughout the Proterozoic. In this view, signs of animal diversification emerge as a unidirectional signal embedded within a deeper record of organic microfossils. We argue here that the absence of animal remains among the large number of equivalent studies from Tonian, Cryogenian and early Ediacaran strata weakens the case for the existence of a cryptic animal biosphere during the Tonian and Cryogenian.

有机微化石的累积记录跨越了数十亿年的地球历史。该记录的大部分由原核生物和原生生物级的真核生物组成，但这种类型的石化还能够捕获有机保存的动物遗骸。最近，很明显，非生物矿化动物群体，否则只能从罕见的特殊化石实例中得知，可以以这种方式保存。鉴于这种高埋藏保真度与有机微化石保存的时间连续性相结合，很明显，这种化石化方式有可能规避影响当前早期动物化石记录的一些主要偏见。尽管如此，还没有尝试调查记录的动物源性有机微化石实例。我们构建了一个全球数据库，其中包含 394 项有机微化石研究，涵盖跨越托尼纪-寒武纪第 5 期/五六期（1 Ga 至 505 Ma）的 399 个沉积岩层。后生动物出现在更广泛的有机微化石档案中。对当前记录的审查表明，有机微化石包含一些关键后生动物进化枝的最古老的身体化石证据，包括毛颚动物、环节动物、普利亚普利亚、“叶足动物”和泛节肢动物、甲壳动物、翼鳃动物，甚至可能是双侧动物。在该记录中还发现了poriferans、chancelloriids、palaeoscolecids、loriciferans、bradoriids、 trilobites、wiwaxiids、软体动物的化石遗骸、 hyoliths、 腕足类动物和脊索动物。我们的数据表明，后生动物衍生的遗骸是寒武纪或更年轻沉积物的孢粉制剂的相对常见成分。在埃迪卡拉纪晚期的几个地层的有机微化石组合中也发现了这种后生动物遗骸，但在整个元古代的较旧沉积物的大量等效制备物中完全没有。在这种观点中，动物多样化的迹象作为嵌入有机微化石更深记录中的单向信号而出现。我们在此争辩说，在来自 Tonian、Cryogenian 和早期埃迪卡拉纪地层的大量等效研究中，没有动物遗骸削弱了 Tonian 和 Cryogenian 期间存在神秘动物生物圈的理由。