Department of Geology, Lund University, Lund, Sweden.
Department of Molecular Biosciences, UTEX Culture Collection of Algae, The University of Texas at Austin, Austin, Texas, USA.
J Phycol. 2024 Oct;60(5):1090-1104. doi: 10.1111/jpy.13499. Epub 2024 Aug 31.
The Cretaceous period is the time of the first appearance of the diatoms in the fossil record. These fossils give us direct evidence of the age and early evolution of the diatom lineage. The fossil record, however, is incomplete and therefore often extrapolated through time-calibrated phylogenies. These two approaches offer different perspectives on the early evolution of diatoms, which is still poorly understood. We compiled the first comprehensive Cretaceous Diatom Database, a tool to investigate the taxonomy, diversity, and occurrence of the earliest known diatom lineages. To further aid the integration and use of the oldest diatom fossils in molecular clock analyses, we present a set of well-documented Cretaceous fossils that can be placed onto molecular phylogenetic trees of extant and extinct species, making them ideal candidates for the calibration of molecular clocks. The analysis of the fossil record and the Cretaceous Diatom Database revealed Cretaceous diversity is substantially greater than previously thought, yet considerable taxonomic work is still needed. The Cretaceous Diatom Database and the list of Cretaceous fossils for calibrating molecular clocks represent valuable resources for future evolutionary and taxonomic studies of modern and fossil diatoms.
白垩纪是化石记录中硅藻首次出现的时期。这些化石为我们提供了硅藻谱系的年龄和早期进化的直接证据。然而，化石记录并不完整，因此经常通过时间校准的系统发育进行推断。这两种方法提供了关于硅藻早期进化的不同视角，而硅藻的早期进化仍然知之甚少。我们编制了第一个综合的白垩纪硅藻数据库，该数据库是研究最早已知硅藻谱系的分类、多样性和出现的工具。为了进一步帮助整合和利用分子钟分析中最古老的硅藻化石，我们提出了一组有充分记录的白垩纪化石，可以将其放置在现存和已灭绝物种的分子系统发育树上，使它们成为分子钟校准的理想候选者。化石记录和白垩纪硅藻数据库的分析表明，白垩纪的多样性比以前认为的要大得多，但仍需要进行大量的分类工作。白垩纪硅藻数据库和用于校准分子钟的白垩纪化石列表为未来现代和化石硅藻的进化和分类研究提供了有价值的资源。
