Taphonomic analysis of the exceptional preservation of early bird feathers during the early Cretaceous period in Northeast China
Taphonomic analysis of the exceptional preservation of early bird feathers during the early Cretaceous period in Northeast China
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DOI：
10.3389/feart.2022.1020594
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发表时间：
2023-01
影响因子：
5.6
通讯作者：
Yan Zhao;Q. Tian;Guanglei Ren;Ying Guo;Xiao-Ting Zheng
中科院分区：
文献类型：
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作者：
Yan Zhao;Q. Tian;Guanglei Ren;Ying Guo;Xiao-Ting Zheng
软组织化石对生命演化和全面认识中生代生态系统的性质具有重要的、不可替代的意义。与其他软组织化石相比，热河生物群的羽毛更常被报道。然而，对这些羽毛的分类分析是缺乏的。本文选取了5个热河生物群系中羽毛保存方式不同的朝阳Sapeornis chaoyangensis早期鸟类标本。其中一个标本，STM 15-36，拥有一整套保存完好的羽毛。寄主沉积物Zr/Rb分析揭示了一个有趣的结果，即样品STM 15-36具有最粗糙的沉积物粒度，但保存最完好的羽毛。对寄主沉积物进行了有机碳同位素和主要元素的地球化学分析，以恢复Sapeornis埋藏时期的古环境。结果表明：seornis STM 15-36埋埋时的古气候较其他4个时期温暖湿润；STM 15-36宿主沉积物为纯陆源有机输入，其余为水生藻类。此外，氧化还原敏感痕量元素分析表明，湖底水保存的Sapeornis STM 15-36是缺氧和受限的，比其他4种更缺氧。因此，初步推断STM 15-36沙鸟的搬运掩埋过程为：STM 15-36沙鸟尸体被短暂强降雨冲积迅速搬运入湖，随后被伴生陆源碎屑快速掩埋；随后的缺氧和受限埋藏环境抑制了Sapeornis STM 15-36及其寄主沉积物的生物扰动和水动力扰动，使其整套羽毛得以完好保存。这一发现为了解热河生物群中化石软组织的特殊保存提供了一个有价值的研究案例。
Fossil soft tissues contain important and irreplaceable information on life evolution, and on the comprehensive understanding of the nature of Mesozoic ecosystems. Compared to other fossil soft tissues, Jehol Biota feathers are more commonly reported. However, taphonomic analysis of these feathers is lacking. Here, five Jehol Biota specimens of early bird Sapeornis chaoyangensis with differently preserved feathers were selected. One specimen, STM 15-36, has a complete set of extraordinarily preserved feathers. An interesting consequence was revealed by their host sediment Zr/Rb analysis that specimen STM 15-36 possesses the coarsest sediment grain size but the best-preserved feathers. More geochemical analyses of host sediments, including organic carbon isotopes and major elements, were conducted to restore the paleoenvironment during those Sapeornis’ burial. The result mainly shows that the paleoclimate when Sapeornis STM 15-36 was buried is warmer and wetter than those of the other four; STM 15-36 host sediment has a pure terrestrial-derived organic input, while the others are aquatic algae. In addition, redox-sensitive trace elements analysis indicates the lake bottom-water preserved Sapeornis STM 15-36 is anoxic and restricted, being more oxygen-depleted than those of the other four. Therefore, the transportation and burial of Sapeornis STM 15-36 were preliminarily inferred as: the carcass of Sapeornis STM 15-36 was transported rapidly into the lake by a short and strong rain flush, and then was buried quickly by the accompanying terrestrial debris; the subsequent anoxic and restricted burial environment inhibited bioturbation and hydrodynamic disturbance on Sapeornis STM 15-36 and its host sediments, allowing its whole set of feathers to be delicately preserved. This finding provides a valuable case study on understanding the taphonomy of fossil soft tissues’ exceptional preservation in Jehol Biota.