We propose a new ecological ranking of the major Phanerozoic biodiversity crises in which the Serpukhovian biodiversity crisis is ranked fifth in ecological impact, lesser than the Late Devonian but greater than the end-Ordovician, and the end-Ordovician mass extinction is ranked sixth. It is interesting that both the end-Ordovician mass extinction and the Serpukhovian biodiversity crisis were triggered by glaciations. Other than that common trigger, the two events were very different. Glaciation in the Ordovician triggered an enormous jump in the extinction rate of marine organisms and was taxonomically very severe, yet the ecological impact of those extinctions was minimal. Glaciation in the Serpukhovian triggered a precipitous drop in the speciation rate but only moderate diversity losses, yet the ecological impact of those diversity losses and ecosystem restructuring was an ecological level of magnitude larger than that seen in the end-Ordovician mass extinction.