Episode 7 of The Story of Life on Earth covers the Great Dying, the extinction at the end of the Permian period about 252 million years ago. It was the worst mass extinction in Earth’s history, and it cleared the way for the dinosaurs.
Before the extinction, the land belonged to synapsids, the mammal relatives. Predators like the saber-toothed gorgonopsians hunted plant-eating dicynodonts across the supercontinent Pangaea.
Then huge volcanic eruptions in Siberia poured carbon dioxide into the air. The planet heated quickly, and the oceans lost much of their oxygen. Between 81 and 96 percent of marine species died out, along with roughly 70 percent of land vertebrate species. The oceans stayed low on oxygen for around five million years.
One of the few winners was Lystrosaurus, a pig-sized, tusked plant eater that spread across the empty land. With the dominant synapsids gone, another group of reptiles got its chance. That group produced the dinosaurs, the subject of the next episode.
Martin Jenkins’s 2019 book Life: The First Four Billion Years marks the mass extinctions on its timeline, and reviewers have praised how much attention it gives to the animals that came before the dinosaurs.
Watch Episode 7 on YouTube, go back to Episode 6, continue to Episode 8, How Dinosaurs Took Over, or see the full series on the YouTube Series page.