Mass extinctions have radically influenced the history of life on Earth. Will we eventually succumb to such a catastrophe? Perhaps, but, in her new book Scatter, Adapt, and Remember, io9 editor in chief Annalee Newitz argues that we can avoid calamity through technological innovation and sifting clues from Deep Time about what allowed some organisms to persist in the face of destruction. One such creature is Lystrosaurus – a tubby, tusked cousin of ours whose kind lived through the worst mass extinction pulse of all time. In this guest essay, Annalee pays tribute to the mascot of survival.
Lystrosaurus: The Most Humble Badass of the Triassic
By Annalee Newitz
One of the greatest survivors in all of Earth’s history was a humble creature named Lystrosaurus. It was a dog-sized animal whose peculiar lineage evolved about 270 million years ago, and looked like a cross between a pig and a lizard. Snub-faced and splay-legged, it was a burrower with powerful front legs who probably dug its own den every night. And somehow, it managed to survive the worst mass extinction the world has ever known.
About 250 million years ago, at the close of the Permian period, an enormous volcano called an igneous province started erupting in the region of the world that would one day be Siberia. At the time, this volcano was at the northern tip of a supercontinent called Pangaea that stretched from the north pole all the way down to the south. The eruption formed massive vents, rifts in the earth that released wave after wave of lava, along with billowing clouds of ash, carbon, and other toxins.
The Siberian igneous province laid waste to the environment for over a thousand years, ultimately releasing as much as to 43,000 gigatons of carbon into the atmosphere. It’s likely that the planet cooled down for a time, then heated up into a devastatingly profound greenhouse. At the same time, all that carbon caused ocean acidification. The resulting climate changes ultimately killed off 95 percent of all species on Earth.
But not Lystrosaurus. This goofy-looking creature became my hero while I was writing my new book, Scatter, Adapt and Remember: How Humans Will Survive a Mass Extinction. It possessed several survival skills, and probably got a few lucky breaks too. Studying Lystrosaurus can teach us a lot about what it takes to survive disaster.
Lystrosaurus was a therapsid, a group often described as the mammal-like reptile branch of the synapsids, a group that eventually evolved into mammals. Though Lystrosaurus‘ progeny died out, they were nevertheless part of a phylogenetic unit whose evolution continues today. So while they are not our direct ancestors, I like to think of these little guys playing a kind of avuncular role in humanity’s evolution.
They certainly had one thing in common with us: they tunneled underground to deal with disaster, just like Permian-era preppers. The shape of Lystrosaurus‘ skull suggests it was a burrower, while its barrel chest may have held lungs capable of pulling in plenty of oxygen even in dusty air, full of contaminants. Spending a lot of time underground is a good survival tactic in a world whose climate is going haywire. Underground food sources are less likely to be affected by airborne particles blocking the sunlight.
It’s also possible that Lystrosaurus‘ adaptation to underground life prepared it for a world whose atmosphere was full of dust and ash for centuries. Those big lungs may have been the perfect way to breathe as the Siberian volcano erupted.
Another way Lystrosaurus survived was simply by walking. A lot. Based on enormous number of fossils found by paleontologists over the past 150 years or so, it seems that Lystrosaurus was also a great wanderer. These splayfooted creatures managed to escape some of the worst effects of the Siberian igneous province by scuttling south. Lystrosaurus was good at locating new ecosystem niches in far-flung places. It speciated — evolving into at least three new species, possibly more — and adapted to the southern part of Pangaea, called Gondwana. They were so successful that at one point in the early Triassic, these synapsids were the single most common vertebrate on land.
Of course Lystrosaurus‘ survival may also have come down to luck. During the early Triassic period, food webs were in flux. According to California Academy of Sciences paleozoologist Peter Roopnarine, who has studied food webs of the period, many ecosystems were simply too unstable to remain intact over the long term. There may have been simply too many predators, including the fierce, toothy ancestors of alligators. And yet for some reason, none of these animals preyed on the herbivore Lystrosaurus. Possibly, at three feet long, Lystrosaurus was just slightly too large to be appealing as a meal.
With seemingly no natural predators, the ability to live underground, and an insatiable wanderlust, Lystrosaurus thrived during the horrific early millennia of the Triassic. These seemingly unstoppable animals watched as the world recovered from the worst mass extinction it had ever endured.
Today, Lystrosaurus is more than just a role model for preppers. It also helped transform the way we understand the Earth. Lystrosaurus fossils provided some of the most persuasive pieces of evidence for plate tectonics in the late 1960s, because their skeletons were found in diverse regions of the world, including Africa, China and Antarctica. This distribution of their remains could only be explained if the continents had once been connected, allowing these land animals to wander from one region to the other.
What is truly inspiring about these animals, though, is that they survived without being deadly warriors. They had no giant teeth nor armored plates for protection. Instead, they survived the early Triassic by adapting their behaviors to new environments, and living absolutely anywhere they could. If these weird lizard-pigs could make it through a mass extinction, there’s hope for humanity after all. Especially if there are no giant crocodiles trying to eat us.
[Top art by Dmitry Bogdanov, image from Wikipedia]