From shallow to deep water: an ecological study of the Hirnantia brachiopod Fauna (Late Ordovician) and its global implications. (29th November 2019)

• Record Type: Journal Article
• Authors: Huang, Bing; Harper, David A. T.; Zhou, Hanghang; Rong, Jiayu
• Is Part Of: Lethaia. Volume 53:Number 3(2020)
• Page Start: 332
• Page End: 344
• Publication Date: 2019-11-29
• Subjects: Ecological transition -- Hirnantia brachiopod Fauna -- Hirnantian -- the end‐Ordovician mass extinction; Paleontology -- Periodicals; Geology, Stratigraphic -- Periodicals; 560
• DOI: 10.1111/let.12360
• Languages: English
• ISSNs: 0024-1164

Abstract

Abstract : A large brachiopod fauna collected through the upper Wanyaoshu Formation (middle Hirnantian), West Yunnan, China displays, for the first time, a vertical transition within the Hirnantia fauna. The inner to mid‐shelf Fardenia – Hirnantia association segues into the deeper water Aegiromena – Anisopleurella association during the Metabolograptus persculptus marine transgression. This transition parallels the pattern apparent in onshore–offshore gradients within the Hirnantian, imitating Walther's Law for facies, instead predicting the seaward transitions between community types within a single transgressive sequence. In addition, large‐sized brachiopods such as Hirnantia and Eostropheodonta become rarer and small‐sized brachiopods, for example, Aegiromena and Anisopleurella more common. It is a rare opportunity to view transformations in community composition and structure within the Hirnantia fauna together with changes in both the size of individuals and populations (from large to small) during the transgression.