Ordovician–Silurian Lilliput crinoids during the end-Ordovician biotic crisis

Abstract

Coincident with the end-Ordovician (end-Katian for crinoids) biodiversity crash, crinoids from Anticosti Island, Quebec, experienced a statistically significant reduction in body size, an evolutionary trend termed the “Lilliput Effect”. This decrease in body size occurred for the fauna as a whole, and data indicate that neither dominant Ordovician nor dominant Silurian clades experienced preferential size decrease. Because the post-extinction fauna with a diminished size is composed of largely new taxa, this example of the Lilliput Effect is regarded as the miniaturization mode. The miniaturization occurred very rapidly; however, the recovery on Anticosti Island did not occur for as many as 7 Ma. This macroevolutionary asymmetry, as demonstrated in many other studies, highlights the need to preserve the biodiversity present on Earth today.