回答你的问题的观点:我们不知道。对大多数生物来说,化石记录是不存在的或者非常零碎。甚至估算物种的数量(这是不太困难的,因为你只需要一个样品的每个物种访问信息)是非常困难的,受到很多影响,许多偏见(看到杰克Sepkoski的作品,例如,大卫。罗普和约翰Alroy看到估计过去生物多样性)的难度。尝试重建海洋无脊椎动物多样性(* * Sepkoski 1978;Alroy et al . 2001年,2008年* *)显示在显生宙的增加(误差,最后几千万年漫长岁月),有5个主要的大规模灭绝事件(最终奥陶纪、泥盆纪晚二叠纪、三叠纪边界,边界三叠纪、侏罗纪和白垩纪/早第三纪的边界)。一般的假设是,生物量增加当多样性增加。实在是没有很强的这种假设的基础,但这基本上是所有我们可以处理。然而一些生物有一个更好的化石记录:硅藻、放射虫、有孔虫和钙质超微化石(主要来自藻类群Haptophyta)构成了大部分的海洋沉积物,因此记录一致且丰富。新生代记录(即过去的66最高产量研究)是相当完整的,但在某些情况下偏见仍足以使我们估算合理丰富的变化。事实上,我目前的研究围绕在沉积物硅藻丰度的变化在过去50最高产量研究(我很乐意完成这个答案当我设法发表一些这方面的工作)。 Without going too much into the details, it seems, in that case, that their abundance (in sediments at least) and their diversity are more or loss synced. The interest of diatoms, in regard to your specific question, is that, today, there are one of the two main oceanic primary producers (along with Haptophyta), oceanic production itself being more or less half of the global production (see [this previous answer of mine](//www.hoelymoley.com/a/137/87)). Their abundance increased significantly at the Eocene/Oligocene boundary and then during the Mid-Miocene. Of course it is possible that in the mean time other phytoplankton (Haptophyta, Dinoflagellates, or others) abundance might have dropped but what makes us think that this is not the case is that changes in diatom abundances during the Cenozoic match changes in atmospheric $pCO_2$ (**Beerling & Royer 2011**), implying a global increase in the net primary production. References: Alroy, J. *et al.*, 2001. [Effects of sampling standardization on estimates of Phanerozoic marine diversification.](http://www.pnas.org/cgi/doi/10.1073/pnas.111144698) PNAS, 98(11): 6261-6266. Alroy, J. *et al.*, 2008. [Phanerozoic Trends in the Global Diversity of Marine Invertebrates](http://dx.doi.org/10.1126/science.1156963). Science, 321: 97-100. Beerling, D. J. & Royer, D. L. 2011. [Convergent Cenozoic CO2 history](http://dx.doi.org/10.1038/ngeo1186). Nature Geosciences, 4: 418-420. Sepkoski J. J. Jr, 1978. [A kinetic model of Phanerozoic taxonomic diversity I. Analysis of marine orders.](http://www.jstor.org/stable/2400203) Paleobiology, 4: 223-251.  Shameless autopromotion: Renaudie, J. & Lazarus, D. B. 2014. [A quantitative review of the Cenozoic diatom deposition history](http://adsabs.harvard.edu/abs/2014EGUGA..16.3829R). EGU General Assembly Conference Abstracts, 16: 3825.