布尔吉斯页岩型特异埋藏生物群在寒武纪之后的大量消失一直是一个未解的科学谜题。据南京地质古生物研究所最新研究报告称，在众多的假说当中，潜居生物的崛起造成后期生物扰动（bioturbation）频繁导致布尔吉斯页岩型生物群在寒武纪之后大量消失是被大部学者认同的一个解释。但是，中国科学院“百人计划”入选者、中国科学院南京地质古生物研究所林日白研究员及其研究团队却提出了有力证据来推翻此假说。

在最新一期Palaeogeography, Palaeoclimatology, Palaeoecology杂志上发表的文章中，林日白等人共研究了323块保存精美的5.13亿年前的属于布尔吉斯页岩型生物群的贵州凯里生物群标本。通过扫描电镜观察拍摄微体粪粒，以及应用最新X光微体扫描设备和三维模拟软件，研究人员成功地还原了棘皮动物化石与潜穴遗迹化石的三维保存关系，证明潜居生物所遗留下来的遗迹化石和其它底栖动物化石是同期存在，共同生活在凯里组的海底。

此论文对布尔吉斯页岩型生物群落中遗迹化石和实体化石的共存关系及其特异埋藏保存条件提供了最新的讯息。

原文摘要：

Palaeogeography, Palaeoclimatology, Palaeoecology doi:10.1016/j.palaeo.2010.03.048

Bioturbation in Burgess Shale-type Lagerst?tten — Case study of trace fossil–body fossil association from the Kaili Biota (Cambrian Series 3), Guizhou, China
Jih-Pai Lina, b, , , Yuan-Long Zhaoc, Imran A. Rahmand, Shuhai Xiaoe and Yue Wangc

a Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
b Dept. of Geology and Geophysics, Yale University, New Haven, CT 06511, United States
c College of Resource and Environment Engineering, Guizhou University, Guiyang 550003, China
d Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
e Dept. of Geosciences, Virginia Tech, Blacksburg, VA 24061, United States

Cruziana, Gordia, Planolites, Rusophycus, and Trichophycus are common ichnological elements of the Kaili Biota. New discoveries based on the examination of 323 specimens include eldoniids, echinoderms, trilobites, monoplacophorans, and non-biomineralizing arthropods that are associated with trace fossils. Based on the observed effects of bioturbation on the preservation of five different animal groups, it is clear that infaunal scavengers/deposit feeders were periodically active on the Kaili sea floor and were able to reach historic layers yielding exceptionally preserved fossils. In general, the average level of infaunal activity is absent to moderate (Ichnofabric Index [i.i.] = 1 to 3) in the Kaili substrate; by contrast, the “Phycodes beds” are completely disturbed by infaunal activity (i.i. = 5). Observed burrow diameter ranges from diminutive ( 0.2 mm) to normal (up to 4.2 mm). Computed tomography allows us to visualize the precise geometry of the trace fossil–body fossil association in three dimensions. We concluded that although some Kaili infaunal animals could bore through the biomineralized echinoderms, they did not appear to have scavenged upon these echinoderms based on our three-dimensional reconstruction. Furthermore, Kaili burrowers can reach the historic layers containing exceptionally preserved fossils without altering soft-tissue preservation. On the other hand, we used conventional techniques to reveal that one burrow is filled with fecal pellets (100–200 μm) at its terminal end. Because most burrows are filled with yellow/brown “coarse sediment”, and because there is no compositional difference between the fecal pellets and the surrounding coarse sediment within the burrow, the origin of the yellow/brown “coarse sediment” is interpreted here as parautochthonous and/or autochthonous and as a result of sediment reworking by deposit (or suspension) feeders. The relative scarcity of soft-part preservation in the Kaili Biota compared to the older Chengjiang Biota and the younger Burgess Shale Biota may be the result of post-burial bio-disturbance due to the relatively high intensity of local bioturbation. It is plausible that oxygenation in deeper sediments (facilitated by bioturbation) allowed carcasses in the Kaili biota to undergo a more extensive period of ‘normal’ decay prior to final burial than in other Cambrian Konservat-Lagerst?tten.