The Cambrian Burgess Shale-type biotas form a globally consistent ecosystem, usually dominated by arthropods. Elements of these communities continued into the Early Ordovician at high latitude, but our understanding of ecological changes during the Great Ordovician Biodiversification Event (GOBE) is currently limited by the paucity of Ordovician exceptionally preserved open-marine faunas. Here we clarify the early stages of the GOBE by describing a new open-marine Konservat-Lagerstätte from the Early Ordovician of Wales. The Afon Gam Biota includes many lineages typical of the Cambrian Burgess Shale-type biotas, but the most abundant groups were sponges, algae and worms, with non-trilobite arthropods being unexpectedly rare. Labile tissues occur abundantly in the sponges and are also present in other groups, including brachiopods and hyoliths. Taphonomic biases are considered and rejected as explanations for arthropod rarity; the preserved biota is considered to be an approximation to the original community composition. We note that other exceptionally preserved communities in the Welsh Ordovician are also sponge-dominated, suggesting a regional change in benthic ecology during the early stages of the GOBE.
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机译:寒武纪Burgess页岩型生物群形成了一个全球统一的生态系统,通常以节肢动物为主。这些群落的元素在高纬度地区一直延续到奥陶纪早期,但是我们对大奥陶纪生物多样性事件(GOBE)期间生态变化的理解受到奥陶纪保存完好的海洋动物稀少的限制。在这里,我们通过描述来自威尔士早期奥陶纪的新型开放式海洋Konservat-Lagerstätte来阐明GOBE的早期阶段。 Afon Gam生物群包括许多寒武纪Burgess页岩型生物群的典型谱系,但最丰富的群是海绵,藻类和蠕虫,非三叶虫节肢动物出乎意料地罕见。不稳定组织大量存在于海绵中,也存在于其他组中,包括腕足动物和葫芦科动物。人们认为并拒绝了节肢偏见作为节肢动物稀有性的解释。被保存的生物群被认为是原始群落组成的近似值。我们注意到,威尔士奥陶纪的其他特别保存的群落也以海绵为主,这表明在GOBE早期,底栖生态系统发生了区域性变化。
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