Trilobite radiations and extinctions – evidence from the Palaeozoic record of China
Trilobite cumulative generic diversity throughout 45 Palaeozoic stages of China is presented. Cambro-Ordovician trilobite diversity is further analyzed at higher resolution by subdividing this interval into 70 time intervals defined by biozones, which enables 13 distinctive phases of diversity to be differentiated. Two different measurements (sampled and range-through) and three methods (total genera, normalized total genera, and total genera per million years) are applied in order to eliminate potential analytical errors. Comparable patterns of radiation and extinction are evident for all methods, and the effect of the end-Ordovician extinction is clearly shown with post-Ashgill diversity an order of magnitude less than that attained in the Cambro-Ordovician.