动物三维探索的兴起引发了前寒武纪-寒武纪生态系统的转变

发布时间：2025年10月30日

近日，中国科学院南京地质古生物研究所早期生命研究团队在湖北宜昌"石板滩生物群"研究中取得重要进展，发现了迄今最古老的复杂三维潜穴系统。这些保存在约5.5亿年前地层中的遗迹化石表明，复杂的动物行为对海底环境的改造比原有的认识提早了近一千万年。这项发现为理解埃迪卡拉纪—寒武纪过渡期间生态系统的重大转型提供了关键行为学证据，相关成果已发表于国际权威综合性学术期刊《科学进展》(Science Advances)上。

距今约5.39亿年前的埃迪卡拉纪-寒武纪转折期，记录了地球历史上最为深刻的生态系统变革。这一时期，后生动物发生了从海底表面二维活动到向沉积物深部三维探索的行为转变，成为推动生态系统变革的重要因素。这种“底质改造”过程，将原本由微生物席主导、结构单一的海洋底质，变成了被生物扰动、层次分明的现代型海底，永久性地改变了地球环境与生命演化的轨迹。

南京古生物所研究员陈哲与博士生刘雅榕，对湖北宜昌“石板滩生物群”（距今约5.5~5.43亿年）的遗迹化石进行了系统研究，发现了Treptichnus属中的多个遗迹化石种，并建立一个新遗迹化石种Treptichnus streptosus. 结合该生物群中已发现的三维遗迹化石Lamonte及蝌蚪状遗迹，深入讨论了动物垂向探索行为出现的演化与生态学意义，并揭示了动物复杂行为在寒武纪大爆发前夕就已出现。

Treptichnus被视为动物首次向沉积物内部进行“三维探索”的标志性遗迹，具有重要的演化生物学、动物行为学和生态学意义，其属内T. pedum的首次出现被正式定义为埃迪卡拉纪-寒武纪的分界标志。石板滩的新发现将这一革命性行为的出现时间大幅提前。研究不仅报道了新种 T. streptosus，还识别出 T. cf. bifurcus, T. rectangularis, T. pollardi 等多个遗迹种，表明当时动物的掘穴行为已经呈现出显著的多样性。

与此同时，石板滩生物群中还保存了Lamonte及蝌蚪状遗迹化石等三维潜穴。这些垂向探索行为的集中出现，反映了早期的沉积物生态分层和复杂觅食行为，代表了造迹生物对底质改造的能力逐渐加强。研究发现，Lamonte在石板滩生物群中产生了密集的生物扰动，不仅破坏了沉积物表面的微生物席，还进一步瓦解了依赖微生物席生存的埃迪卡拉型生物的生态环境，从而成为约5.5亿年前第一次埃迪卡拉生物群灭绝事件的潜在原因之一。

这些复杂行为的出现及其生态累积效应，在埃迪卡拉纪末期持续增强，促使微生物席逐渐衰退，不断动摇埃迪卡拉型生物的生态根基，同时为其他后生动物多样性演化创造了新的生态机遇。在多种生物与非生物因素的协同作用下，这一过程最终推动了埃迪卡拉纪—寒武纪生态系统的深刻转型。

这项研究也进一步确认，石板滩生物群保存了丰富多样的遗迹化石和实体化石组合，是研究隐生宙-显生宙之交生态系统巨变的重要窗口。

研究得到国家自然科学基金委项目资助。

论文相关信息：Zhe Chen* and Yarong Liu, Advent of three-dimensional sediment exploration reveals Ediacaran-Cambrian ecosystem transition, Sci. Adv. 11.

论文地址： https://doi.org/10.1126/sciadv.adx9449

Shibantan Trace Fossils Reveal Animal 3D  Exploration  emerged approximately  550 Million Years Ago

Recently, the Early Life research team from the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, has made significant progress in the study of the "Shibantan Biota" in Yichang, Hubei Province, discovering the oldest known complex three-dimensional burrow systems to date. These trace fossils, preserved in strata approximately 550 million years old, indicate that complex animal behaviors were modifying the seafloor environment nearly 10 million years earlier than previously thought. This discovery provides key behavioral evidence for understanding the major ecosystem transformation during the Ediacaran–Cambrian transition.

The Ediacaran–Cambrian transition period, around 539 million years ago, records one of the most profound ecosystem revolutions in Earth's history. A crucial factor driving this ecological change was the shift in metazoan behavior from simple two-dimensional surface activities to three-dimensional exploration deep into the sediments. This process of "substrate revolution" transformed the seafloor from a uniform, matground-dominated system into a heterogeneously layered, bioturbated modern-style seabed, permanently altering the course of Earth's environmental and biological evolution.

Researchers CHEN Zhe and PhD student LIU Yarong from the Nanjing Institute of Palaeontology, CAS, conducted a systematic study of trace fossils from the Shibantan Biota in Yichang, Hubei (approx. 550–543 million years old). They identified multiple ichnospecies within the genus Treptichnus and established a new ichnospecies, Treptichnus streptosus. By integrating these findings with previously discovered three-dimensional trace fossils such as Lamonte and tadpole-shaped traces from the same biota, the study provides an in-depth discussion on the evolutionary and ecological significance of the emergence of vertical exploration behavior in animals. The related findings have been published in the authoritative international comprehensive academic journal Science Advances, revealing that complex animal behaviors emerged on the eve of the Cambrian explosion.

Treptichnus is regarded as a landmark trace fossil, signifying the first "3D exploration" by animals into the sediment, holding significant importance in evolutionary biology, animal behavior, and ecology. The first appearance of T. pedum within this genus is formally defined as the marker for the Ediacaran–Cambrian boundary. The new discovery from the Shibantan Biota significantly predates the emergence of this revolutionary behavior. The study not only reports the new species T. streptosus but also identifies other ichnospecies such as T. cf. bifurcus, T. rectangularis, and T. pollardi, demonstrating that animal burrowing behaviors had already achieved significant diversity by that time.

Simultaneously, the Shibantan Biota also preserves other three-dimensional burrows such as Lamonte and tadpole-shaped traces. The concentrated appearance of these vertical exploration behaviors reflects early sediment ecological stratification and complex foraging strategies, indicating a gradually strengthening capacity of trace-making organisms to engineer substrates. The study found that Lamonte produced intensive bioturbation within the Shibantan Biota, which not only disrupted the microbial mats on the sediment surface but also further dismantled the ecological environment of Ediacara-type organisms that relied on these mats. This suggests bioturbation could have been a potential contributing factor to the first extinction event of the Ediacara biota around 550 million years ago.

The emergence of these complex behaviors and their cumulative ecological effects intensified towards the end of the Ediacaran Period, leading to the gradual decline of microbial mats, continuously undermining the ecological foundation of Ediacara-type organisms while simultaneously creating new ecological opportunities for the diversification of other metazoans. Driven by the synergy of various biological and non-biological factors, this process ultimately contributed to the profound transformation of ecosystems across the Ediacaran–Cambrian transition.

This research further confirms that the rich and diverse assemblage of trace fossils and body fossils preserved in the Shibantan Biota provides a crucial window for studying the major ecosystem changes at the transition between the Precambrian and the Phanerozoic Eon.

This research was supported by the National Natural Science Foundation of China.

Reference: Zhe Chen* and Yarong Liu, Advent of three-dimensional sediment exploration reveals Ediacaran-Cambrian ecosystem transition, Sci. Adv. 11.

作者：陈哲

单位：中国科学院南京地质古生物研究所