寒武系小碳化石(SCFs)的研究进展及意义

所谓SCFs(Small Carbonaceous Fossils),可译为"小碳化石",其大小跨越了传统的微观与宏观界线(以肉眼可见与否为标准),是一个特定化石群体的统称。它的实质含义,是指通过氢氟酸(HF)等无机酸浸泡泥岩/页岩样品后经过滤、浓缩而获得的一类体积微小的有机碳质薄膜化石,包括后生动物残片、丝状藻/菌类碎片、疑源类等类型。在小碳化石概念被正式提出之前,国外学者曾先后用有机质壁微体化石(Organic-walled microfossils)、碳质微体化石(Carbonaceous microfossils)与布尔吉斯页岩型微体化石(Burgess Shale-type microfossils)来表述此类化石。目前在国际上,与布尔吉斯页岩型(BST)化石库和奥斯坦(Orsten)型化石库一样,小碳化石已经成为寒武纪古生物学及生物埋藏学等领域研究的一个重要的新窗口;同时,通过三类特异埋藏化石的对比研究,实现优势互补,从而能够更好地阐述早期生物的演化与多样性。

RESEARCH PROGRESS AND SIGNIFICANCE OF THE CAMBRIAN SMALL CARBONACEOUS FOSSILS (SCFs)

The term "SCFs" stands for Small Carbonaceous Fossils, which defines a special group of fossils, with size ranges across the conventional boundary between microscopic and macroscopic views. SCFs are also known as "orga-nic-walled microfossils", "carbonaceous microfossils", and/or "Burgess Shale-type microfossils". Due to more findings worldwide SCFs is now becoming a new important window for Cambrian palaeontological and taphonomical studies because it can bridge the preservation gaps between Cambrian Lagersttten, including Burgess Shale-type (BST) macrofossils and Orsten-type fossils. SCFs were recovered through a series of procedures as followed: macerate each sample of mudstone/shale with hydrofluoric acid (HF) until it disaggregated, dilute the solution to neutrality, filter the sample through a sieve and then concentrate the residues. Concentrated residues can be picked for SCFs, including metazoan fragments, filamental algae/fungi and acritarchs. Furthermore, SCFs combined with other Cambrian fossil Lagersttten help to document unknown life forms and broaden the diversity of early life.