Lilliput effect in freshwater ostracods during the Permian-Triassic extinction

The Lilliput effect following the Permian-Triassic mass extinction and its aftermath has been documented in a variety of marine animal groups, but it is less known in terrestrial and freshwater invertebrates. Here we present new investigations of the size variations of terrestrial ostracods of the genus Darwinula based on fossil records from a Permian-Triassic section on the northern limb of the Dalongkou Anticline section in Northwest China. Quantitative analyses reveal that ostracod test sizes decreased sharply through the terrestrial Permian-Triassic mass extinction interval. The Lilliput effect in terrestrial ostracods is characterized by the extinction of large taxa and the rise of small-sized and elongate new forms, coupled with the dramatic loss of conchostracans, charophytes, and the blooming of lycopod spores. The size decrease in terrestrial ostracods, following the biotic crisis through the Permian-Triassic interval, was probably triggered by several interacting events, including global warming, anoxia, and enhanced sediment input following acid rain and wildfire.