"Leptictidium" lived in the European subtropical forests of the Eocene. From the beginning of this period, the temperature of the planet rose in one of the quickest (in geological terms) and most extreme episodes of global warming in the geological record, termed Paleocene–Eocene Thermal Maximum. It was an episode of quick and intense (of up to 7 °C in high latitudes) warming which lasted less than 100,000 years. The thermal maximum caused a great extinction which is used to distinguish the Eocene fauna from that of the Paleocene.