Doushan Tuo Biofacies (Life Before the Radiation of Early Animals)

Author: Yuan Xunlai et al.
Publisher:
Publish Date: 2002-07-01
Features: In southern China, along the banks of the Yangtze River, a vast area known as the "Yangtze Platform" extends from Yunnan in the west to Jiangsu and Zhejiang in the east, including southern Jiangxi and Hunan, as well as northern Hubei and Anhui. This region is characterized by well-exposed late Precambrian strata. These strata are continuous, with minimal metamorphism, and preserve a rich fossil record. Over several decades of work by two generations, the "Weng'an Biota," "Miaohe Biota," and "Lantian Plant Biota" were discovered in the late Precambrian Doushantuo Formation, primarily consisting of multicellular fossil organisms.
The Weng'an Biota was found in Weng'an County, Guizhou Province. It is three-dimensionally preserved in phosphatic rocks of the Doushantuo Formation as microfossils. This biota includes a variety of benthic and planktonic eukaryotic organisms. The fossil biota serves as evidence of early eukaryotic multicellularity, tissue differentiation, sexual dimorphism, and morphological diversity. It showcases the early multicellular life landscape in warm shallow seas before the Cambrian Explosion and the appearance of the Ediacaran Biota, representing a crucial stage in the evolution of early life from simplicity to complexity. It provides a new window for understanding the early evolution of multicellular life. The emergence of morphological diversification of metazoans during the Doushantuo Period is a result of the co-evolution of organisms and the environment following the Neoproterozoic Cryogenian period.
Large, spiny radiolarians are the planktonic types in this biota. Benthic, attached multicellular algae include red algae, brown algae, and green algae. The microtubular stinging cells of diploblastic animals and animal embryos may represent the evolutionary level of metazoans during this period. Cyanobacteria and bacteria are primary producers, playing a significant role in the material and energy cycles of the Doushantuo marine ecosystem. The shallow marine ecosystem of the Doushantuo Period, dominated by multicellular algae and metazoans, replaced the prokaryotic stromatolite-microbial mat ecosystem that had persisted on Earth for nearly 3 billion years.