Labechia carbonaria Smith 1932 in the Early Carboniferous of England;affinity,palaeogeographic position and implications for the geological history of stromatoporoid-type sponges

作     者：Stephen Kershaw Consuelo Sendino Stephen Kershaw;Consuelo Sendino

作者机构：Department of Life SciencesBrunel University LondonKingston LaneUxbridge UB83PHUK Department of Earth SciencesNatural History MuseumCromwell RoadLondon SW75BDUK 

出 版 物：《Journal of Palaeogeography》 (古地理学报（英文版）)

年 卷 期：2021年第10卷第1期

页      面：1-18页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学] 

基　　金：British Geological Survey  BGS 

主　　题：Stromatoporoids Holkerian Viséan Carboniferous Rugosa Labechia carbonaria Labechia conferta 

摘      要：Stromatoporoid sponges were very abundant during the middle Palaeozoic Era and are thought to disappear at the end of the Devonian Period in the Hangenberg Crisis. However, there are records of organisms with stromatoporoid-type structure in Carboniferous strata, the subject of this study. The Viséan fossil Labechia carbonaria Smith 1932 has been discussed previously in literature and its affinity has not been confirmed. In this study, the type material of L. carbonaria collected from the middle part of the Frizington Limestone Formation(previously called Seventh Limestone), Holkerian Substage, stored in the Natural History Museum(London, UK) and British Geological Survey(Keyworth, UK) was re-examined. The Holkerian Substage, in which L. carbonaria was found, lies between ca 335–339 Ma, and the Frizington Limestone Formation ranges from topmost Arundian to upper Holkerian, so middle Frizington Limestone Formation is likely approximately 337 Ma. L. carbonaria comprises thick long pillars connected by thin curved cyst plates consistent with the structure of the stromatoporoid genus Labechia. However, a common opinion is that L. carbonaria fossils may be mistaken for fragments of rugose corals,but there are problems with assigning it to the Rugosa. In vertical section(VS) L. carbonaria could be mistaken for a transverse section(TS) of a Carboniferous rugose coral. However, in TS L. carbonaria shows the rounded cross sections of stromatoporoid pillars. If it was a coral, septal sheets of the VS of a coral should be seen. For a rugose affinity to still apply, a coral structure would have to be composed of free trabeculae, but these are not known after the middle of the Devonian Period;there are no corals of Early Carboniferous age with the structure of ***. Another interpretation, that L. carbonaria is a chaetetid, is discounted because it lacks calicles and is very different in structure from chaetetids. We conclude that L. carbonaria is a stromatoporoid. Becau