Late Ordovician (Caradoc-Ashgill) brachiopod faunas with Foliomena based on data from China
Late Ordovician (Caradoc-Ashgill) brachiopod faunas with Foliomena based on data from China
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DOI：
10.2307/3515394
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发表时间：
1999-10
期刊：
影响因子：
1.6
通讯作者：
Jiayu Rong;Renbin Zhan;D. Harper
中科院分区：
文献类型：
--
作者：
Jiayu Rong;Renbin Zhan;D. Harper
对浙江-江西两省交界地区的一个从近岸到近海的样带中的Ashgill中期带Foliomena的腕足动物群的新调查表明，Foliomena folium（Barrande）的数量显著增加，其区系组成、多样性和丰度从浅水环境到深水环境有显著变化。根据中国和其他地区的资料，将具有叶幕的动物群划分为典型群丛和非典型群丛。典型的Foliomena动物群以Foliomena沿着为特征，并带有一些独特的成分（如Dedzetina，Leptestiina，Christiania和Cyclospira），基本上位于深水环境（主要是BA 5-6）。非典型Foliomena动物群的代表是那些组合，其中罕见的Foliomena是与各种属，如Kassinella在不同的地方代表较浅的环境（外BA 3-BA 4）。此前报道的Foliomena动物群的年龄为最晚的Caradoc到早期的Ashgill。新的中国资料表明，它的范围从早期Caradoc（Nemagraptus gracilis生物带）到中期阿什吉尔。它在阿什吉尔早期达到了进化的顶峰，并在赫南阶之前灭绝。在古生物地理学上，它与巴尼索夫省内的8个古板块有关，浅水Hirnantia动物群后来在Hirnantia广泛分布。在一系列深度的Foliomena协会的分类组成和生态位的连续和逐渐的变化可能表明，与Foliomena动物群的分布可能并不总是由温跃层的位置控制。典型的Foliomena动物群在时间和空间上的分布证实了在海洋底栖动物中的一个成功的早古生代生态实验：腕足动物将其范围扩大到空的深水底栖生态位，以利用与黑暗相关的软基质，可能贫营养条件。
New investigations of mid-Ashgill brachiopod faunas with Foliomena in an onshore to offshore transect in the border region of Zhejiang-Jiangxi provinces, East China, indicate a remarkable increase in numbers of Foliomena folium (Barrande) with significant variations of faunal composition, diversity, and abundance from shallow-water to deep-water environments. Based on data from China and elsewhere, faunas with Foliomena are partitioned into typical and atypical associations. The typical Foliomena fauna is characterized by Foliomena along with some distinctive constituents (such as Dedzetina, Leptestiina, Christiania, and Cyclospira), and is essentially located in deep-water environments (mainly BA 5-6). The atypical Foliomena fauna is represented by those assemblages in which rare Foliomena is associated with various genera such as Kassinella at different localities representing shallower environments (outer BA 3-BA 4). The Foliomena fauna previously was reported as latest Caradoc to early Ashgill in age. New Chinese data demonstrate that it ranges from the early Caradoc (Nemagraptus gracilis Biozone) to the mid-Ashgill. It reached its evolutionary acme in the early Ashgill and became extinct before the Hirnantian. Paleobiogeographically, it is associated with eight paleoplates within the Kosov Province, where the shallow-water Hirnantia fauna was widely distributed later in the Hirnantian. Continuous and gradual changes in the taxonomic composition and ecological niches of the Foliomena associations across a range of depths may indicate that the distribution of faunas with Foliomena may not be controlled always by the position of the thermocline. Distribution of the typical Foliomena fauna in time and space verifies a successful early Paleozoic ecological experiment in the marine benthos: brachiopods expanded their ranges into vacant deep-water benthic niches to exploit soft substrates associated with dark, possibly oligotrophic conditions.