Department of Ecology, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Biogéosciences UMR6282, CNRS, Université Bourgogne Franche-Comté, 21000 Dijon, France.
Sci Rep. 2017 Mar 24;7:45160. doi: 10.1038/srep45160.
The pattern and sequence of the decomposition of the Pipidae African dwarf frog (Hymenochirus boettgeri) is tracked in an experiment with microbial mats in order to explore soft tissue preservation over three years. Frog decay in microbial mats is preceded by rapid entombment (25-30 days) and mediated by the formation of a sarcophagus, which is built by a complex microbial community. The frog carcasses maintained a variety of soft tissues for years. Labile organic structures show greater durability within the mat, cells maintain their general shape (bone marrow cells and adipocytes), and muscles and connective tissues (adipose and fibrous tendons) exhibit their original organic structures. In addition, other soft tissues are promptly mineralized (day 540) in a Ca-rich carbonate phase (encephalic tectum) or enriched in sulphur residues (integumentary system). The result is coherent with a bias in soft-tissue preservation, as some tissues are more likely to be conserved than others. The outcomes support observations of exceptionally preserved fossil anurans (adults and tadpoles). Decomposition in mats shows singular conditions of pH and dissolved oxygen. Mineralization processes could be more diverse than in simple heterotrophic biofilms, opening new taphonomic processes that have yet to be explored.
为了探索三年内软组织的保存情况，本实验跟踪了非洲矮蛙（Hymenochirus boettgeri）的分解模式和顺序。微生物垫中青蛙的腐烂是由快速埋葬（25-30 天）引起的，并通过形成石棺来介导，石棺是由复杂的微生物群落构建的。青蛙尸体多年来一直保持着各种软组织。在垫子内，不稳定的有机结构具有更大的耐久性，细胞保持其一般形状（骨髓细胞和脂肪细胞），肌肉和结缔组织（脂肪和纤维肌腱）保持其原始的有机结构。此外，其他软组织会在富含钙的碳酸盐相中（脑顶盖）迅速矿化（第 540 天）或富含硫残留物（表皮系统）。结果与软组织保存的偏向一致，因为有些组织比其他组织更容易保存。研究结果支持对异常保存的化石无尾目动物（成体和蝌蚪）的观察。垫子中的分解表现出独特的 pH 值和溶解氧条件。矿化过程可能比简单的异养生物膜更加多样化，为尚未探索的新埋藏过程开辟了可能性。
