Evolutionary rates of mid-Permian tetrapods from South Africa and the role of temporal resolution in turnover reconstruction
Evolutionary rates of mid-Permian tetrapods from South Africa and the role of temporal resolution in turnover reconstruction
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DOI：
10.1017/pab.2018.17
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发表时间：
2018-08
期刊：
影响因子：
2.7
通讯作者：
M. Day;R. Benson;C. Kammerer;B. Rubidge
中科院分区：
文献类型：
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作者：
M. Day;R. Benson;C. Kammerer;B. Rubidge
抽象的。南非的主卡鲁盆地（Main Karoo Basin）包含一个从中二叠世到早侏罗世的近连续大陆沉积序列，跨度为1.8亿年。该层序的陆栖脊椎动物提供了区域性起源和灭绝的高分辨率地层记录，特别是中晚二叠世。到目前为止，数据仅在粗略的地层分辨率调查使用的方法，是有偏见的不均匀的采样率，限制了我们的了解动态的多样化，通过这一重要的时间段。在这里，我们应用强大的方法（间隙填充和修改后的间隙填充率）的物种丰富度，起源率和灭绝率的模式的推断的一个子集，1321可靠地确定的化石出现解决约50米的地层间隔。该数据集提供了0.3-0.6百万年的近似时间分辨率，并表明灭绝率在中二叠世Abrahamskraal组的上100米处大幅增加，对应于Tapinocephalus组合带（AZ）的最新部分。在同一时间段内，始发率仅略有上升，不足以弥补这些损失。对上覆Teekloof组（对应于Pristognathus和Tropidostoma AZ）下部的子采样物种丰富度估计值较低，表明物种丰富度在主要灭绝脉冲后至少保持了150 - 300万年的低水平。一个高度不均匀的类群丰度频率分布，这是典型的与营养不稳定的灭绝后动物群，事实上开发前不久，由于dicynodont Diictodon的外观和增殖的灭绝率升高的顶点。我们的研究结果为陆地脊椎动物中的Capitanian（“结束瓜达卢佩”）灭绝事件提供了强有力的支持，并建议进一步的高分辨率定量研究可能有助于解决古生物学家对这一事件缺乏共识的问题。
Abstract. The Main Karoo Basin of South Africa contains a near-continuous sequence of continental deposition spanning ∼80 Myr from the mid-Permian to the Early Jurassic. The terrestrial vertebrates of this sequence provide a high-resolution stratigraphic record of regional origination and extinction, especially for the mid-late Permian. Until now, data have only been surveyed at coarse stratigraphic resolution using methods that are biased by nonuniform sampling rates, limiting our understanding of the dynamics of diversification through this important time period. Here, we apply robust methods (gap-filler and modified gap-filler rates) for the inference of patterns of species richness, origination rates, and extinction rates to a subset of 1321 reliably-identified fossil occurrences resolved to approximately 50m stratigraphic intervals. This data set provides an approximate time resolution of 0.3–0.6 Myr and shows that extinction rates increased considerably in the upper 100m of the mid-Permian Abrahamskraal Formation, corresponding to the latest part of the Tapinocephalus Assemblage Zone (AZ). Origination rates were only weakly elevated in the same interval and were not sufficient to compensate for these extinctions. Subsampled species richness estimates for the lower part of the overlying Teekloof Formation (corresponding to the Pristerognathus and Tropidostoma AZs) are low, showing that species richness remained low for at least 1.5–3 million years after the main extinction pulse. A high unevenness of the taxon abundance-frequency distribution, which is classically associated with trophically unstable postextinction faunas, in fact developed shortly before the acme of elevated extinction rates due to the appearance and proliferation of the dicynodont Diictodon. Our findings provide strong support for a Capitanian (“end-Guadalupian”) extinction event among terrestrial vertebrates and suggest that further high-resolution quantitative studies may help resolve the lack of consensus among paleobiologists regarding this event.