生物谷Bioon.com 訊,，布爾吉斯頁巖型特異埋藏生物群在寒武紀(jì)之后的大量消失一直是一個未解的科學(xué)謎題,。據(jù)南京地質(zhì)古生物研究所最新研究報告稱，在眾多的假說當(dāng)中,，潛居生物的崛起造成后期生物擾動（bioturbation）頻繁導(dǎo)致布爾吉斯頁巖型生物群在寒武紀(jì)之后大量消失是被大部學(xué)者認(rèn)同的一個解釋,。但是，中國科學(xué)院“百人計劃”入選者,、中國科學(xué)院南京地質(zhì)古生物研究所林日白研究員及其研究團(tuán)隊卻提出了有力證據(jù)來推翻此假說,。
在最新一期Palaeogeography, Palaeoclimatology, Palaeoecology雜志上發(fā)表的文章中，林日白等人共研究了323塊保存精美的5.13億年前的屬于布爾吉斯頁巖型生物群的貴州凱里生物群標(biāo)本,。通過掃描電鏡觀察拍攝微體糞粒,，以及應(yīng)用最新X光微體掃描設(shè)備和三維模擬軟件，研究人員成功地還原了棘皮動物化石與潛穴遺跡化石的三維保存關(guān)系,，證明潛居生物所遺留下來的遺跡化石和其它底棲動物化石是同期存在,，共同生活在凱里組的海底,。
此論文對布爾吉斯頁巖型生物群落中遺跡化石和實體化石的共存關(guān)系及其特異埋藏保存條件提供了最新的訊息,。(生物谷Bioon.com)
生物谷推薦原文摘要：
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.
