Around 540 million years ago, Earth’s biosphere underwent a pivotal transformation, shifting from a microbe-dominated world to one teeming with animal life, as nearly all major animal phyla appeared abruptly in the fossil record over a very short geological time interval. This landmark evolutionary event is known as the Cambrian Explosion. However, this surge in animal diversity was cut short around 513 million years ago by the Phanerozoic eon’s first mass extinction, the Sinsk Event—with an extinction rate on par with the planet’s five most severe mass extinctions, the so-called “Big Five.” In its aftermath, global biodiversity remained low for around 50 million years, until the onset of the Great Ordovician Biodiversification Event.