Was there a Cambrian explosion on land?

土地的殖民化是生命史上的一个关键转变。分子钟分析表明，早古生代陆地上节肢动物和植物的快速辐射，与寒武纪海洋大爆发重叠，但化石记录令人沮丧地有限。该项目将联合收割机古生物学和计算方法相结合，以弥补化石记录中的这一空白，并建立陆地生态系统进化的时间尺度。早古生代陆相沉积物将采用低操作酸提取程序进行研究，以分离小型碳质化石（SCFs）。SCFs是一个独特的保存窗口，用于保存罕见的小型生物。在20世纪80年代和90年代，许多陆地沉积物中的节肢动物SCF被报道，但此后一直被忽视。初步分析的煤球揭示了特殊的SCFs适合与现存的和古生代的类群进行比较。有问题的SCF的系统发育位置和非海洋起源将使用地球化学技术进行测试，为识别最古老的陆地生态系统提供可靠的标准。SCF记录将通过使用断层扫描法在博物馆收藏的Rhynie燧石和Mazon Creek生物化石中修订节肢动物来补充。这些化石证据将为陆地化的新时间尺度提供一套强有力的校准，这反过来将成为测试有关陆地生命多样化驱动因素的假设的支柱。

The colonisation of land was a key transition in the history of life. Molecular clock analyses imply a rapid radiation ofarthropods and plants on land in the early Palaeozoic, overlapping with the Cambrian explosion in the sea, but the fossilrecord is frustratingly limited. The project will combine palaeontological and computational methods to bridge this gap inthe fossil record and establish a timescale for the evolution of terrestrial ecosystems. Early Palaeozoic terrestrial depositswill be investigated using a low-manipulation acid extraction procedure to isolate small carbonaceous fossils (SCFs).SCFs are a unique preservation window for small organisms that rarely fossilise. Arthropod SCFs from numerousterrestrial deposits have been reported in the 1980 and 1990s but have been overlooked since. Preliminary analyses ofcoal balls reveal exceptional SCFs suitable for comparison with extant and Palaeozoic taxa. The phylogenetic positionand non-marine origin of problematic SCFs will be tested using geochemical techniques, providing reliable criteria forrecognising the oldest terrestrial ecosystems. The SCF record will be complemented by revising arthropods from theRhynie chert and Mazon Creek biotas in museum collections using tomography. This fossil evidence will provide a set ofrobust calibrations for a new timescale of terrestrialisation, which will in turn serve as a backbone for testing hypothesesabout the drivers of the diversification of life on land.