The story
In the aftermath of the Great Dying, a stocky, tusked plant eater called Lystrosaurus becomes the most common land vertebrate on Earth. It is a dicynodont, a beaked relative of the mammal ancestors, ranging from cat size to pig size. In South Africa's Karoo Basin it makes up the great majority of backboned fossils in some Early Triassic layers, and the same animal turns up in India, China, Russia and Antarctica.
Lystrosaurus probably survived because it was a burrower and an undemanding generalist, able to live on tough plants in the hot, thin-aired world left behind by the Siberian Traps eruptions. Its spread across what are now separate continents became textbook evidence for continental drift: when Edwin Colbert found Lystrosaurus in the Transantarctic Mountains in 1969, it showed that Antarctica had once been joined to Africa and India. Within a few million years the Lystrosaurus world gave way to archosaurs, the group that includes dinosaurs and crocodile ancestors.
Why it mattered
- Lystrosaurus shows how an emptied ecosystem fills with a few hardy survivors before diversity returns.
- Its fossils on several continents gave a vivid proof of the connected southern land that Wegener's continental drift required.
- Its decline cleared space for the archosaurs, whose descendants include the first dinosaurs.
Sources
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