Fenxiang biota:a new Early Ordovician shallow-water fauna with soft-part preservation from China

分乡生物群:中国一个新发现的有软组织保存的早奥陶世浅水型动物群（英文）

Our perception of biodiversity in the geological past is incomplete and biased because most organisms did not have mineralized skeletons and therefore had little chance of fossilization. This especially refers to shallow- water marine environments, rarely represented by localities with exceptional preservation of fossil material （known as taphonomic windows or Konservat-Lagerstaitten）. Such extraordinary “windows” may markedly broaden our knowledge of biodiversity of the past. Here, we show a review of the invertebrate fossils from recently discovered locality in the Lower Ordovician Fenxiang Formation of Hubei Province in southern China revealing exceptional preservation of soft tissues. The fauna, generally of shal- low-water aspect, contains linguloid brachiopods with a remarkably preserved pedicle, the oldest traces of nema- tode life activities, the oldest reliable record of hydroids, the first fossil antipatharian corals, a pyritized colonial organism of unknown affinity, supposed arthropod ap- pendages, probable phosphatized scalidophoran worm embryo and other fossils. Our discovery supports the opinion that the famous soft-bodied preservation of Bur- gess Shale- or Chengjiang-type did not vanish from the fossil record in post-Cambrian times. The new finding represents a prelude to the Great Ordovician Biodiversifi- cation Event and provides evidence for calibration of molecular clock of several invertebrate lineages.

以有软躯体保存而闻名的伯吉斯页岩型或澄江型化石生物群的发现,为我们打开了一扇全面认识地质历史中生物多样性的窗口.在湖北宜昌地区新发现的早奥陶世分乡生物群就是这样的一个窗口.该动物群包括了保存有肉茎结构的舌形贝类、最早的线虫生活痕迹、最早而可靠的水螅虫化石记录、最早的黑珊瑚化石记录、一种亲缘关系不明的群体生物化石、节肢动物附肢化石和可疑的scalidophoran蠕虫胚胎化石等.同时,新发现为若干无脊椎动物类群分子钟的标定提供了直接的化石证据.