Carapace growth in modern and fossil Spinicaudata (Crustacea: Branchiopoda): testing its applicability in unravelling Middle Jurassic to Late Cretaceous lacustrine faunal turnover in NE China

在泥盆纪时期，刺尾甲壳类动物成为湖泊群落的重要组成部分。它们在超过3亿年的时间里保持着高度丰富，主宰着湖泊无脊椎动物群落。早白垩世全球多样性高峰之后，晚白垩世出现了急剧下降，并在早新生代被排除在湖泊环境之外。化石记录中棘足动物数量的减少是整个湖泊生态系统进化的一个重要方面。今天，Spinicaudata代表了一种适应临时、新鲜到低盐湿地的生态特化进化枝，这些湿地通常不支持更高营养水平的动物。本项目旨在通过计算大型底栖动物群落组成在氧、温度和养分有效性等环境梯度上的变化率，揭示控制中国东北中侏罗世-晚白垩世fossillagerstätten湖泊动物更替的因素。将对4个目标层的每个化石层理平面进行生物地球化学代理数据（delta15N、delta13Corg、Corg/N、GDGT生物标志物）编制，进一步进行统计检验。许多层理平面含有单特异的棘足虫组合，使甲壳形态成为湖泊生态系统变化的另一个重要信息来源。化石形态沿环境梯度变化的模式将与提出的针对氧气、养分有效性和温度对现代物种甲壳生长影响的饲养实验结果进行比较。

Spinicaudatan crustaceans became important elements of lake communities during Devonian times. They remained highly abundant for more than 300 million years, dominating the lacustrine invertebrate community. The Early Cretaceous global diversity peak was succeeded by a proposed dramatic decline during the Late Cretaceous and their exclusion from lake environments during the early Cenozoic. That decline of spinicaudatan presence in the fossil record forms an important aspect of general lake ecosystem evolution. Today, Spinicaudata represent an ecologically specialized clade adapted to temporary, fresh- to oligohaline wetlands that commonly do not support animals of higher trophic levels. The project aims at unravelling factors that controlled lacustrine faunal turnover in Middle Jurassic–Late Cretaceous fossillagerstätten of NE China by calculating the rate of change in macrobenthic community composition along environmental gradients of oxygen, temperature and nutrient availability. Biogeochemical proxy data (delta15N, delta13Corg, Corg/N, GDGT biomarkers) will be compiled for each fossiliferous bedding plane of four targeted formations for further statistical testing. Numerous bedding planes contain monospecific assemblages of Spinicaudata, rendering carapace morphology an additional important source of information for lake ecosystem change. Patterns of fossil morphological change along environmental gradients will be compared with results of proposed rearing experiments that target effects of oxygen, nutrient availability and temperature on carapace growth in modern species.