Kimmig Julien, Couto Helena, Leibach Wade W, Lieberman Bruce S
Biodiversity Institute, University of Kansas, Lawrence, KS, 66045, USA.
Department of Geosciences, Environment and Spatial Planning/ICT, University of Porto, Faculty of Sciences, Rua do Campo Alegre 687, 4169-007, Porto, Portugal.
Naturwissenschaften. 2019 May 25;106(5-6):27. doi: 10.1007/s00114-019-1623-z.
Soft-bodied preservation is common in the Cambrian but comparatively rare in the Ordovician. Here, a new deposit preserving soft-bodied fossils is reported from the Middle Ordovician (Dapingian-Darriwilian) upper Valongo Formation of northern Portugal. The deposit contains the first known occurrences of soft-bodied fossils from the Middle Ordovician (Dapingian-Darriwilian) of Portugal and is the first Ordovician example of soft-tissue preservation involving carbonaceous films from the Iberian Peninsula. It also represents the lone deposit of soft-bodied fossils from the Middle Ordovician of northern Gondwana. Thus temporally, it lies between the exceptional deposits of the Lower Ordovician of Fezouata (Morocco) and the Upper Ordovician of the Soom Shale (South Africa); it also serves as a biogeographic link between these and the various Ordovician soft-bodied deposits in Laurentia. The soft-bodied fossils come from the deep-water slates of the upper part of the Valongo Formation and include a discoidal fossil questionably referable to Patanacta, wiwaxiid sclerites, and a possible pseudoarctolepid arthropod.
软体化石保存现象在寒武纪很常见，但在奥陶纪相对较少。在此，报道了葡萄牙北部中奥陶世（达平阶—达瑞威尔阶）上瓦隆戈组一个保存软体化石的新矿床。该矿床包含了葡萄牙中奥陶世（达平阶—达瑞威尔阶）已知最早出现的软体化石，并且是伊比利亚半岛首个涉及碳质膜的奥陶纪软体组织保存实例。它也是冈瓦纳北部中奥陶世唯一的软体化石矿床。因此，在时间上，它介于摩洛哥菲祖阿塔下奥陶统的特殊矿床和南非苏姆页岩上奥陶统之间；它还作为这些矿床与劳伦系中各种奥陶纪软体化石矿床之间的生物地理联系。这些软体化石来自瓦隆戈组上部的深水板岩，包括一个可疑归属于帕塔纳克塔的盘状化石、威瓦西虫的骨片以及一种可能的伪弧鳞甲节肢动物。
