Evolutionary dynamics of the Permian–Triassic foraminifer size: Evidence for Lilliput effect in the end-Permian mass extinction and its aftermath

There is growing evidence of the Lilliput effect in the end-Permian mass extinction and its aftermath. However, very little has been published on assessing the Lilliput effect on protozoans in the Early Triassic based on quantitative analysis of a great quantity of samples from outcrop sections. This study investigates foraminiferal test size variations through the Changhsingian to the Olenekian based on fossil records from three outcrop sections in South China. The sharp reduction in foraminifer sizes coincides with the first or main episode of the end-Permian mass extinction. Foraminifers remained small in sizes in the early Induan. Their body sizes increased slowly in the late Induan to Olenekian, but never recovered to the pre-extinction test size levels. The Lilliput effect on foraminifera in the aftermath of the end-Permian crisis is indicated by the extinction of large taxa, decrease in size for surviving taxa and rise of small-sized new forms. Physiological reactions of various foraminifer groups reveal that several defaunation events such as anoxia, ocean acidification, and global warming that prevailed through the Permian–Triassic interval may be responsible for both the end-Permian crisis and the Lilliput effect.