CNRS, IRD, IFSTTAR, ISTerre, Université Grenoble Alpes, Université Savoie Mont Blanc, 38000, Grenoble, France.
Biology Centre of Academy of Sciences, Institute of Entomology, Branisovska 31, České Budějovice, Czech Republic.
Sci Rep. 2020 Jun 29;10(1):10575. doi: 10.1038/s41598-020-67412-9.
Animal fossils preserved in various geological materials, such as limestone, claystone, or amber, provide detailed information on extinct species that is indispensable for retracing the evolution of terrestrial life. Here, we present the first record of an animal fossil preserved in opal formed by weathering with such high-resolution details that even individual cuticle hairs are observed. The fossil consists of the exoskeleton of a nymphal insect belonging to the order Hemiptera and either the family Tettigarctidae or the Cicadidae. This identification is based on anatomical details such as the tibial and femoral morphology of the forelegs. The exoskeleton of the insect was primarily zeolitized during the alteration of the host rocks and later sealed in opal deposited by silica-rich fluids derived from the continental weathering of the volcanic host rocks. Organic matter is preserved in the form of amorphous carbon. This finding makes opal formed by rocks weathering a new, complementary source of animal fossils, offering new prospects for the search for ancient life in the early history of Earth and possibly other terrestrial planets such as Mars, where weathering-formed opal occurs.
保存在各种地质材料中的动物化石，如石灰岩、泥灰岩或琥珀，为追溯陆地生命的进化提供了有关已灭绝物种的详细信息，这些信息是不可或缺的。在这里，我们首次记录了一种以如此高分辨率保存的动物化石，甚至可以观察到单个表皮毛。该化石由属于半翅目昆虫目或 Tetigartidae 科或 Cicadidae 科的若虫外骨骼组成。这种鉴定是基于前腿的胫节和股骨形态等解剖学细节。昆虫的外骨骼在宿主岩石的蚀变过程中主要沸石化，然后被富含硅的流体形成的蛋白石封闭，这些流体来自火山宿主岩石的大陆风化。有机质以无定形碳的形式保存。这一发现使由岩石风化形成的蛋白石成为一种新的、补充性的动物化石来源，为在地球早期历史以及可能的其他类地行星（如火星）中寻找古代生命提供了新的前景，在火星上，风化形成的蛋白石很常见。
