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 L. carbonaria . 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. Because the beginning of the Carboniferous Period was ca 359 Ma, stromatoporoids thus occur approximately 22 million years after their purported disappearance at the end-Devonian Hangenberg Crisis. L. carbonaria, together with other rare occurrences in Carboniferous strata of stromatoporoid-form sponges Newellia mira (Newell) in USA, and uncertain taxa Komia Korde and Palaeoaplysina Krottow that have been attributed to stromatoporoids by some authors, supports some published views that end-Devonian stromatoporoid extinction may not have been as final as is traditionally interpreted. Thus Mesozoic stromatoporoids may represent resurgence of sponge lineages that survived the late Palaeozoic, perhaps in uncalcified form. Palaeogeographically, during the Early Carboniferous, the UK was positioned in low latitudes and in a central location of global distribution of reefal buildups during the late Palaeozoic continental assembly towards Pangaea. Thus it is curious that L. carbonaria is found in only one place; future search may determine its true palaeographic distribution, with potential reconsideration of the extinction of stromatoporoids at the end of the Devonian Period.

中文翻译：

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Labechia carbonaria Smith 1932 在英国早石炭纪；亲缘关系、古地理位置和对层孔型海绵地质历史的影响

间孔海绵在中古生代非常丰富，据认为在泥盆纪末期的汉根堡危机中消失了。然而，在本研究的对象石炭纪地层中有具有层孔型结构的生物的记录。Viséan 化石 Labechia carbonaria Smith 1932 之前已在文献中讨论过，但其亲和力尚未得到证实。在这项研究中，L. carbonaria 的典型材料从弗里辛顿石灰岩组（以前称为第七石灰岩）的中部收集，霍尔克里亚亚台，储存在自然历史博物馆（英国伦敦）和英国地质调查局（英国基沃思） ) 被重新审查。发现 L. carbonaria 的 Holkerian Substage 位于约 335-339 Ma，和弗里辛顿石灰岩组的范围从阿伦迪安的最顶部到上霍尔克阶，所以中间的弗里辛顿石灰岩组可能大约为 337 Ma。L. carbonaria 由厚长的柱子组成，这些柱子由薄弯曲的胞囊板连接，与层孔虫属 Labechia 的结构一致。然而，一个普遍的观点是 L. carbonaria 化石可能会被误认为是皱褶珊瑚的碎片，但将其分配给 Rugosa 存在问题。在垂直剖面 (VS) 中，L. carbonaria 可能被误认为是石炭纪皱纹珊瑚的横剖面 (TS)。然而，在 TS L. carbonaria 中显示出层孔柱的圆形横截面。如果是珊瑚，应该可以看到珊瑚VS的隔片。为了使皱纹的亲和力仍然适用，珊瑚结构必须由游离的小梁组成，但这些在泥盆纪中期之后就不为人知了；没有L. carbonaria结构的早石炭世珊瑚。另一种解释认为 L. carbonaria 是 chaetetids，因为它没有 calicles 并且在结构上与 chaetetids 大不相同。我们得出结论，L. carbonaria 是一种层孔虫。由于石炭纪的开始时间约为 359 Ma，因此，层孔虫在泥盆纪汉根堡危机末期据称消失后大约 2200 万年出现。L. carbonaria，连同美国石炭纪层孔状海绵 Newellia mira (Newell) 中的其他罕见事件，以及一些作者将其归因于层孔虫的不确定分类群 Komia Korde 和 Palaeoaplysina Krottow，支持一些已发表的观点，即泥盆纪末层孔虫灭绝可能不像传统解释那样最终。因此，中生代层孔虫可能代表了在晚古生代幸存下来的海绵谱系的复兴，也许是未钙化的形式。从古地理上讲，在早石炭纪，英国位于低纬度地区，并且在古生代晚期大陆组装向 Pangaea 期间处于全球珊瑚礁堆积分布的中心位置。因此奇怪的是，L. carbonaria 只在一个地方被发现；未来的搜索可能会确定其真正的古地理分布，并可能重新考虑泥盆纪末期层孔虫的灭绝。因此，中生代层孔虫可能代表了在晚古生代幸存下来的海绵谱系的复兴，也许是未钙化的形式。从古地理上讲，在早石炭纪，英国位于低纬度地区，并且在古生代晚期大陆组装向 Pangaea 期间处于全球珊瑚礁堆积分布的中心位置。因此奇怪的是，L. carbonaria 只在一个地方被发现；未来的搜索可能会确定其真正的古地理分布，并可能重新考虑泥盆纪末期层孔虫的灭绝。因此，中生代层孔虫可能代表了在晚古生代幸存下来的海绵谱系的复兴，也许是未钙化的形式。从古地理上讲，在早石炭纪，英国位于低纬度地区，并且在古生代晚期大陆组装向 Pangaea 期间处于全球珊瑚礁堆积分布的中心位置。因此奇怪的是，L. carbonaria 只在一个地方被发现；未来的搜索可能会确定其真正的古地理分布，并可能重新考虑泥盆纪末期层孔虫的灭绝。在晚古生代大陆向泛大陆组装期间，英国位于低纬度和全球珊瑚礁堆积分布的中心位置。因此奇怪的是，L. carbonaria 只在一个地方被发现；未来的搜索可能会确定其真正的古地理分布，并可能重新考虑泥盆纪末期层孔虫的灭绝。在晚古生代大陆向泛大陆组装期间，英国位于低纬度和全球珊瑚礁堆积分布的中心位置。因此奇怪的是，L. carbonaria 只在一个地方被发现；未来的搜索可能会确定其真正的古地理分布，并可能重新考虑泥盆纪末期层孔虫的灭绝。