Data from: The Lilliput effect in crinoids at the end of the Oceanic Anoxic Event 2: a case study from Poland

The Cretaceous period (145-66 Ma) consists of several Oceanic Anoxic Events (120-80 Ma), stimulated by global greenhouse effects. The Oceanic Anoxic Event 2 (OAE2) occurred worldwide from the late Cenomanian to the early-middle Turonian, causing a significant faunal turn-over, mostly in marine biota pushing some species to the brink of extinction. Some organisms also underwent morphological changes, including reduction in size. This anoxic event drove other changes, e.g., habitats or strategy of life. Here, we show that stalkless crinoids (comatulids) from the Turonian of Poland adapted to unfavorable environmental conditions by reducing their body size. Furthermore, at the moment when environmental factors become favorable again, these crinoids regained their regular (pre-event) size. This phenomenon most probably illustrates the so-called “dwarfing” mode of the Lilliput Effect.