Life › The age of dinosaurs › Life recovers in the Triassic
Lystrosaurus
c. 252–247 million years ago· Fossil or site· Animals
Well establishedStrong fossil, genetic or geological evidence.
A pig-sized, beaked plant-eating synapsid that survived the Great Dying and became the commonest land vertebrate afterward.
See it on the Life map →What happened
Lystrosaurus was a dicynodont, a group of plant-eaters with a turtle-like beak and two tusks. Most were about a meter long, with a stocky body built for digging. In the earliest Triassic it vastly outnumbered other land vertebrates in South Africa's Karoo Basin, and it lived across much of Pangaea, from Russia and China to India and Antarctica. Bone growth rings show survivors grew fast and bred young, typical of animals in stressed, unstable environments.
Why it matters
A rare winner of the extinction that shows which traits help in a crisis. Its Antarctic fossils also helped confirm that the southern continents were once joined.
The evidence (fossils, genes, rocks)
Thousands of skeletons from the Karoo; finds in India, China, Russia and Antarctica, where Edwin Colbert's team found it in 1969; bone-growth studies published in 2016.
Still debated
Why it survived when most relatives died, through burrowing, a tough diet, fast breeding or luck, is still argued.
Connections (3)
▸Life recovers in the Triassic was dominated at first by LystrosaurusWell established
The connection
In the bleak earliest Triassic, Lystrosaurus became by far the commonest land vertebrate across southern Pangaea. With few competitors or predators, this burrowing plant-eater spread widely. Its dominance is a classic "disaster fauna": a few hardy generalists filling a landscape emptied by extinction.
When and how
Earliest Triassic, about 252–247 million years ago, in South Africa's Karoo Basin, India, China, Russia and Antarctica.
The evidence
Bed-by-bed fossil counts in the Karoo show Lystrosaurus vastly outnumbering other vertebrates just above the extinction boundary.
Debates and open questions
How long its dominance lasted, and how much the counts reflect true abundance rather than how fossils were collected, are discussed.
▸Lystrosaurus survived The Great Dying (end-Permian extinction)Well established
The connection
Lystrosaurus is one of very few dicynodont lineages known to cross the extinction boundary. Possible advantages include burrowing to escape heat, a beak and tusks for tough roots and stems, and breeding young. A 2016 study found that post-extinction individuals grew fast and reproduced early, as animals do in stressed populations.
When and how
Late Permian to earliest Triassic, about 252 million years ago, best documented in South Africa's Karoo Basin.
The evidence
Lystrosaurus fossils occur both below and above the boundary in the Karoo, and bone growth rings record how fast individuals grew.
Debates and open questions
Whether its survival came from its traits or from luck, and how many of its species crossed the boundary, are debated.
▸Lystrosaurus fossils in Antarctica supported Continental drift & plate tectonicsWell established
The connection
Lystrosaurus, a pig-sized plant-eating relative of mammals, was already known from South Africa, India and China. Finding it in Antarctica in 1969 showed that land animals had walked between these continents about 250 million years ago, strong support for plate tectonics, which was then newly accepted.
When and how
Coalsack Bluff, Transantarctic Mountains, 1969, by an Ohio State University expedition including geologist David Elliot and paleontologist Edwin Colbert.
The evidence
The Antarctic bones match species from South Africa's Karoo Basin, and a land animal like this could not have crossed an ocean.
Debates and open questions
Because it lived across much of Pangaea, it confirms connections but not exact positions; how it survived the Permian extinction so well is still studied.