A fish and tetrapod fauna from Romer's Gap preserved in Scottish Tournaisian floodplain deposits
A fish and tetrapod fauna from Romer's Gap preserved in Scottish Tournaisian floodplain deposits
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DOI：
10.1111/pala.12395
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发表时间：
2018-10
期刊：
影响因子：
2.6
通讯作者：
B. K. A. Otoo;J. Clack;T. Smithson;C. Bennett;T. Kearsey;M. Coates
中科院分区：
文献类型：
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作者：
B. K. A. Otoo;J. Clack;T. Smithson;C. Bennett;T. Kearsey;M. Coates
泥盆纪末期的大灭绝被认为是脊椎动物进化的转折点，使四足动物，软骨鱼类和放线菌的辐射。直到最近，“罗默缺口”使早石炭世成为泥盆纪和晚石炭世之间的一个黑匣子，但现在新的图尔奈阶地区正在填补这一间隔。最近的工作已经恢复了意想不到的四足动物和肺鱼的多样性。然而，图尔奈动物群的组成仍然知之甚少。在这里，我们报告了一个图尔奈阶脊椎动物群，来自苏格兰伯恩茅斯巴拉根组暴露的一个特征良好的狭窄地层间隔。微体化石表明微咸的条件和沉积学表明低能量泥石流植被泛滥平原。一系列的脊椎动物骨骼大小被保存下来。根齿类是最具代表性的，可分为两个类群。肺鱼有几个物种，几乎所有的物种都是巴拉根组的特有物种。有两个命名的四足动物，Aytonerpeton和Diploradus，至少还有另外两个。Gyracanths，holocephalans和actinopterygian鱼类的化石较为罕见。这种材料与来自其他巴拉根矿床的脊椎动物化石相比很好。动物区系相似性分析，使用更新的数据集泥盆纪石炭纪（吉韦蒂安Serpukhovian）网站证实了一个持久的泥盆纪/石炭纪分裂。将数据分为海洋和非海洋分区表明，与海洋环境相比，非海洋环境中的泥盆纪-石炭纪动物群具有更大的连续性。这些结果与最新的化石发现一致，并表明泥盆纪-石炭纪的过渡在不同的环境和不同的分类群中进行不同。
The end‐Devonian mass extinction has been framed as a turning point in vertebrate evolution, enabling the radiation of tetrapods, chondrichthyans and actinopterygians. Until very recently ‘Romer's Gap’ rendered the Early Carboniferous a black box standing between the Devonian and the later Carboniferous, but now new Tournaisian localities are filling this interval. Recent work has recovered unexpected tetrapod and lungfish diversity. However, the composition of Tournaisian faunas remains poorly understood. Here we report on a Tournaisian vertebrate fauna from a well‐characterized, narrow stratigraphic interval from the Ballagan Formation exposed at Burnmouth, Scotland. Microfossils suggest brackish conditions and the sedimentology indicates a low‐energy debris flow on a vegetated floodplain. A range of vertebrate bone sizes are preserved. Rhizodonts are represented by the most material, which can be assigned to two taxa. Lungfish are represented by several species, almost all of which are currently endemic to the Ballagan Formation. There are two named tetrapods, Aytonerpeton and Diploradus, with at least two others also represented. Gyracanths, holocephalans, and actinopterygian fishes are represented by rarer fossils. This material compares well with vertebrate fossils from other Ballagan deposits. Faunal similarity analysis using an updated dataset of Devonian–Carboniferous (Givetian–Serpukhovian) sites corroborates a persistent Devonian/Carboniferous split. Separation of the data into marine and non‐marine partitions indicates more Devonian–Carboniferous faunal continuity in non‐marine settings compared to marine settings. These results agree with the latest fossil discoveries and suggest that the Devonian–Carboniferous transition proceeded differently in different environments and among different taxonomic groups.