作者：李志恒，艾莉达，Thomas A. STIDHAM，王 敏，邓 涛
摘要：报道了来自中国西北地区中新世晚期临夏盆地的一件鸵鸟化石，该标本包括鸵鸟的部分颈椎以及气管，由于缺乏物种级别的鉴定特征，被暂定为Struthio sp.。新标本还保留了平齿三趾马(Hipparion platyodus)的部分头骨。利用多种分析测试方法，对该鸵鸟骨骼的微观特征进行了详细研究，以探讨临夏鸵鸟的埋藏条件和古气候背景。在鸵鸟化石的一个脱矿化的骨碎片中发现了软组织(内源性血管和红细胞的化石残留)。同时光学显微镜和扫描电镜成像显示，化石组织切片中存在显著的细菌改变(骨侵蚀现象)。这是中新世临夏盆地脊椎动物遗体中软组织的首次报道。通过相关的地质和沉积学证据与新的古生物数据相结合，认为季风气候可能是造成鸟类化石早期埋葬期间微生物侵蚀的原因，接下来延续了8百万年左右的盆地剧烈的干旱化作用，导致了微生物活动的停止，并进一步导致了成岩作用后期孔隙方解石的沉淀。这项工作显示出跨学科(包括形态学、沉积学、地球化学和软组织分析)研究可以更好地揭示中国西北临夏盆地柳树组的中新世晚期的动物群更替、气候和分子保存。
关键词：临夏盆地，中新世，三趾马，鸵鸟，软组织，血管，细菌，微观聚焦破坏
Exceptional preservation of an extinct ostrich from the Late Miocene Linxia Basin of China
LI Zhi-Heng, Alida M. BAILLEUL, Thomas A. STIDHAM, WANG Min, DENG Tao
Abstract Here we report a new avian fossil from the Late Miocene Linxia Basin, Northwest China, with exceptional soft-tissue preservation. This specimen preserves parts of cervical vertebrae and tracheal rings that are typically ostrich-like, but cannot be diagnosed at the species level. Therefore, the fossil is referred to Struthio sp. The new specimen was preserved in association with a partial skull of Hipparion platyodus. To explore the soft tissue preservation in a fossil deposited in a terrestrial setting, we applied a combination of analytic methods to investigate the microscopic features of the fossilized avian bone. Bacterial alterations (bone bioerosion) were revealed by light microscopy and petrographic sections under SEM imaging. Soft-tissues (fossilized remnants of endogenous blood vessels and red blood cells) were preserved in one demineralized bone fragment and also observed in the in-situ ground-section. These are the first records of soft-tissue preservation in vertebrate remains from the Late Miocene Linxia Basin. Associated geological and sedimentological evidence combined with our new data provide insights into the postmortem taphonomic conditions of this ostrich specimen. A seasonal monsoon might have facilitated the microbial erosion penecontemporaneous with the burial of the specimen. This study encourages interdisciplinary research involving morphology, sedimentology, geochemistry, and histological soft-tissue analyses to better understand the Late Miocene faunal turnovers, climates, and fossil preservation in the Liushu Formation in northwestern China.
Key words Linxia Basin, Miocene, Hipparion, Struthio, soft-tissues, blood vessels, bacteria, microscopic focal destructions
