A new ecological-severity ranking of major Phanerozoic biodiversity crises

► The ecological severity of the major Phanerozoic biodiversity crises is ranked. ► Crisis ecological severity is decoupled from the magnitude of biodiversity loss. ► Givetian crisis is a palaeoecological analog for modern invasive-species event. ► The Capitanian (Middle Permian) crisis is fifth in ecological severity. ► The “Big Five” end-Ordovician crisis is seventh in ecological severity.