The blood-curdling Permian monsters that ruled the Earth before dinosaurs

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Emmanuel Lafont/ BBC (Credit: Emmanuel Lafont/ BBC)

Long before T. rex, the Earth was dominated by super-carnivores stranger and more terrifying than anything dreamed up by Hollywood.

Around a quarter of a billion years later, on a sunny day in March 2021, Julien Benoit was handed a rather unpromising container and invited to take a look. He was working in a pleasantly cool office at Iziko Museum of Natural History in Cape Town, South Africa, where he had been invited to visit the university’s fossil collections. The vessel was a very old, simple cardboard box.

“It hadn’t been opened for at least 30 years,” says Benoit, an associate professor of evolutionary studies at the University of the Witwatersrand, Johannesburg. Inside was a jumble of bones, including countless skulls, many of which had been mislabelled. As he was sorting through and re-classifying them – assigning them to long-extinct species – he noticed a small, shiny surface.

“It was an exciting moment. I immediately knew what I was looking at,” says Benoit. With a wide smile, he went to visit his colleague and asked to borrow her microscope to take a closer look. The shiny surface belonged to a tooth. This one was pointy and rounded, and it was embedded in the skull of another animal, probably a member of the same species. Benoit believes that two wolf-sized individuals had been fighting for dominance before one of their smaller teeth snapped off.

But this wasn’t a tooth from any dinosaur. It was an artefact of a long-forgotten world – one immortalised in stone long before T. rex, Spinosaurus or Velociraptor made their debut. The skull belonged to an unidentified species of gorgonopsian – a group of slick apex predators which stalked the Earth around 250 to 260 million years ago, chasing down large prey and ripping off chunks of their flesh to swallow whole.

This was the Permian, an obscure era of geological history where the planet was ruled by giant, bone-chilling beasts that ran with a characteristic waddle and sometimes snacked on sharks. During this living nightmare, there were occasionally more carnivores around than there were prey for them to eat on land.

Jurassic World: Rebirth v The Permian As the latest instalment of the Jurassic Park franchise is released, Zaria Gorvett explores the peculiar predators of the Permian – ancient animals arguably far creepier and more experimental than anything dreamed up by Hollywood.

A strange world

The Permian began some 299 to 251 million years ago, when all the land on Earth had coalesced into a single, rabbit-shaped lump – the supercontinent Pangaea – surrounded by a vast, global ocean called Panthalassa.

This was an era of extremes. It opened with an ice age that turned the southern half of the continent into a continuous block of ice and locked up so much water, global sea levels dropped by up to 120m (394ft). Once this was over, the supercontinent gradually warmed up and dried out. With such an expanse of continuous land, the interior did not benefit from the cooling or moistening effects of the ocean, creating swathes of wasteland. By the middle Permian, central Pangaea was mostly desert scattered with conifers, punctuated by the occasional flood. Parts were nearly uninhabitable, sometimes experiencing air temperatures of up to 73C (163F) – hot enough to slow-roast a turkey.

Emmanuel Lafont/ BBC The Permian was filled with bizarre creatures, such as the wrinkly herbivore Moschops – aesthetically like frogs, but the size of muskoxen (Credit: Emmanuel Lafont/ BBC)

“So quite a lot of aridity, but nonetheless wetter down the edges, and certainly in the northern and southern hemispheres, there was plenty of vegetation,” says Paul Wignall, professor of palaeoenvironments at the University of Leeds in the UK.

Then towards the end of the Permian, the entire planet abruptly heated up by about 10C (60F) – roughly double the worst case scenario today if greenhouse gas emissions continue to rise unchecked. This set the scene for the largest mass extinction in Earth’s history, and the conditions in which the dinosaurs would come to thrive.

But during this era, the evolution of T. rex was still some way away. In fact, most of the iconic dinosaurs we’re familiar with today were about as close to existing in the Permian as we are to their time now. Instead, the largest land animals were the synapsids – a peculiar group with a kaleidoscopic array of body shapes and features, from the newt-like Cotylorhynchus, with an oddly tiny head and the mass of a small moose, to the goofy Estemmenosuchus, reminiscent of a hippo wearing a lumpy papier-mâché party hat.

The synapsids shared their world with a variety of other eccentric wildlife. The skies were ruled by dragonfly-like insects, Meganeuropsis, the size of ducks. In fresh water, there were 33ft (10m)-long carnivorous amphibians to contend with – their long, snapping snouts resembling those of crocodiles. Meanwhile, the oceans were patrolled by mysterious shark-like fish with serrated circular “saws” attached to their mouths. It’s thought that Helicoprion used their brutal apparatus to slice open the shells of ammonites and cut through the bodies of large, fast-moving prey.

“I mean, there were so many weird and wacky creatures… I think it just highlights what a vibrant time this was,” says Suresh Singh, a visiting research fellow in the School of Earth Sciences at the University of Bristol in the UK. Indeed, this was the first time that four-legged animals had mastered living entirely on land. Before the Permian was the Age of Amphibians, when most species were still tied to water for at least part of their lives, Singh explains.

But synapsids had a major advantage over amphibians – they could incubate their young within their own bodies, or lay large eggs that retained their own moisture. They essentially had their own portable “private pond”, so they no longer needed lakes or rivers to reproduce.

The group also developed waterproofing on their bodies, so they could live in a wide variety of environments. While some of the first synapsis had scales, others are thought to have had tough, naked skin. In general, they were slow-moving, cold-blooded animals – but they still found a way to get their claws on their favourite meal: meat.

Pioneers of terror

Back in the Permian, the synapsids were utterly unlike anything which had come before. And one of the features that really set them apart from the competition was their mouthfuls of teeth. Whether an animal’s diet called for crushing, chewing, tearing or snipping-off chunks of food – often flesh – these beasts were well-equipped for the task. Rather than just having many similar-shaped teeth like their ancestors, they had a whole Swiss Army knife in their mouths, from incisors to canines.

“So, the herbivores are eating loads of different plants that provide more nutrients,” says Singh. This allowed them to grow larger bodies which, in turn, meant more calories for carnivores – allowing them to become giants. “Synapsids got big really quickly,” says Singh. Soon Pangaea was swarming with predators.

Enter Dimetrodon, the Permian’s answer to the Komodo dragon. These animals were three-and-a-half times bigger than their modern counterparts, weighing up to 250kg (551lbs) and somewhat more imposing – with tall, radiating “sails” that ran along the entire lengths of their backs. These apex predators swaggered around the swampier parts of Pangaea for tens of millions of years, eating anything they could get their teeth into – from small reptiles and amphibians to titanic, barrel-bodied synapsids like Cotylorhynchus.

At one site in Texas, palaeontologists found that there were 8.5 times more Dimetrodon than there were large prey animals – a ratio suggesting a radical overabundance of predators, compared to what you might expect based on modern food chains. (In a private game reserve in South Africa today, for example, a typical lioness might kill around 16 large prey animals per year.)

This mysterious so-called “meat shortage” on land was solved, however, when scientists discovered the sail-backed predator’s teeth mingled with the skeletons of Xenacanthus sharks. Dimetrodon had been filling the gaps in its diet by hunting the jumbo freshwater fish – and vice versa. Nearby the Xenacanthus remains, the researchers found Dimetrodon bones which had been chewed up by Xenacanthus.

Emmanuel Lafont/ BBC Like other early synapsids, Dimetrodon would have had a splayed walk reminiscent of that of crocodiles (Credit: Emmanuel Lafont/ BBC)

But one feature of Dimetrodon has left scientists pondering for centuries: what were the spiny “sails” on their backs for? In 1886, the luxuriously moustachioed palaeontologist Edward Drinker Cope suggested that a similar feature on a close relative of the genus might have acted as a series of literal sails, like those on a boat. Cope speculated that the animals used their sails to cruise around lakes, catching the wind. However, Cope was no stranger to a spectacular blunder – and he was wrong.

The next idea was that Dimetrodon’s sail acted like a solar panel, helping the animals to warm up quickly so that they could chase down their prey. Alas, the laws of physics put that theory down too. Using Dimetrodon’s size to estimate its typical metabolic rate, researchers calculated that their sails would have been useless for thermoregulation in smaller members of the group, which nevertheless still invested heavily in building these elaborate structures. In fact, the sails could have put some species of Dimetrodon at risk of hypothermia, by radiating heat away from the body. Instead, it’s thought that they played a role in courtship, helping the monsters to entice mates.

As the Permian progressed, so did Dimetrodon’s gastronomic tastes. While initially they tended to hunt prey that were smaller or the same size as them, eventually they graduated to more ambitious feasts – tackling increasingly larger prey. And here again, teeth were everything: later Dimetrodon had serrated and curved teeth, ideal for gripping and tearing flesh from prey that couldn’t be swallowed whole. They could also replace their teeth if they got lost or broken – a major advantage if you’re shearing off tough chunks of meat.

But despite their serrated teeth, Dimetrodon never quite honed all the equipment necessary for efficiently capitalising on the new abundance of very large prey, says Singh. What Permian super-carnivores really needed, he explains, were wider jaws. This would create more room for muscles to attach, allowing for a more powerful bite.

And this left a gap in the market. Other flesh-eaters were more than happy to fill it.

Slick predators

The largest predator of the Permian was Anteosaurus. Like the mutant offspring of a tiger and a hippo, they grew to around 6m (19.7ft) long, with an appetite to match. “It’s quite a prize [when you excavate one], because you don’t find a lot of them,” says Benoit. With muscular jaws, powerful arms and tough, bone-crunching teeth, these dominant carnivores reigned across Pangaea around 260 to 265 million years ago.

To add to their spine-chilling look, and frame their massive teeth, Anteosaurus had ridges of bone on their skulls above the eye sockets, evoking the ears of a big cat. “They would have been super scary to look at… it’s the closest thing you have to a T. rex in the Permian,” says Benoit. “The head, in general, is very well designed for killing large animals and crushing their bones,” he says.

Emmanuel Lafont/ BBC Benoit thinks of Anteosaurus as the cheetah of its day (Credit: Emmanuel Lafont/ BBC)

The predators were also surprisingly fast. In 2021, Benoit and colleagues looked at the inner ear of Anteosaurus in detail, squeezing the skull of a young teenager into a CT scanner. The region is often fine-tuned for balance in agile hunters, and the researchers found that this specimen’s was radically different to that of other synapsids. He compares the predator’s unique adaptations to those of cheetahs or the Velociraptor. “It’s very, very special,” he says. “It’s very well developed.”

The team also found features in the brain which indicated that Anteosaurus had an impressive ability to stabilise its gaze. “So that means, when it locked on a prey, it would not stop following it,” says Benoit.

But the supremacy of Anteosaurus turned out to be short lived – they vanished in a mass extinction around 260 million years ago. Soon it was the time of the gorgonopsians, the mightiest of which were Inostrancevia.

With sabre-fangs and skulls up to 70cm (2.3ft) long, Inostrancevia were fast, dynamic hunters in the mould of polar bears. “If you include the root, you’re looking at teeth in the neighbourhood of 20-30cm long (8-12in),” says Christian Kammerer, a research curator in palaeontology at the North Carolina Museum of Natural Sciences. There’s very little evidence of what their skin would have looked like, but based on scraps of fossilised skin from other synapsids, he thinks they most likely had a thick, rhino-like hide.

To be eaten by one of these Permian predators would have been an abrupt, gruesome affair.

Like Benoit’s gorgonopsian skull, Inostrancevia have been found in the Karoo basin, a fossil site in South Africa just south of the Kalahari desert which has yielded thousands of fossils from the Permian.

Today the Karoo is a swathe of dry, open plains the size of Germany, known as the “land of thirst”. But 250 million years ago, the region was relatively lush – centred around an inland sea fed by a network of rivers. “There would have been ferns and horsetails and early sorts of Gymnosperms like pine trees, gingkos. At this point in time, there were no flowering plants, so no flowers, no grass of any kind,” says Kammerer.

In this prehistoric environment, large prey were abundant. Huge herds of dicynodonts – hippo-like herbivores with beaks similar to those of tortoises – roamed the landscape alongside colossal, heavily armoured reptiles known as pareiasaurs. The first sign of danger for these ambling plant-eaters was probably an Inostrancevia leaping out of a thicket or from behind a hill, says Kammerer. Based on their bodily proportions, he thinks they were likely to have been ambush predators.

After a short chase, Kammerer suggests that Inostrancevia may have subdued its prey with its forelimbs and gone for the kill with its powerful jaws and sabre-teeth – possibly using them for a bit of disembowelling. Then they would rip off chunks of flesh and swallow them whole. “They were incapable of chewing,” says Kammerer.

Emmanuel Lafont/ BBC Inostrancevia had an ‘indeterminate’ growth pattern, like tortoises – they just kept getting bigger as long as they lived (Credit: Emmanuel Lafont/ BBC)

Inostrancevia could afford to be a bit careless. Unlike the sabre-toothed cats which inhabited the world much more recently and possibly overlapped with modern humans, Inostrancevia could easily replace broken or lost teeth, like sharks and many reptiles do. “[Fossilised] sabre-toothed cats that are found with broken fangs are often inferred to have died of starvation as a result of that,” says Kammerer.

However, for all their adaptations as pro-level hunters, Kammerer believes that the very presence of Inostrancevia in South Africa was an ominous sign – one which foreshadowed the greatest mass extinction in Earth’s history. Because as it happens, they should never have been there at all.

Until recently, the only Inostrancevia ever discovered had been found in Russia, which even back in the Permian would have been on the other side of the world to the Karoo – separated by a 7,000-mile (11,265km) trek across the inhospitable centre of Pangaea. Instead, South Africa was thought to have been exclusively populated with other, smaller gorgonopsians, like Benoit’s face-biters.

Then around a decade ago, a fossil collector stumbled upon an Inostrancevia in the Karoo. Kammerer was intrigued. “I immediately thought, how is this here?” he says.

A Great Dying

Today a clue remains in the form of the Siberian traps, a region spanning around 5 million sq km (1.9 million sq miles), made entirely of basaltic rock. The area was formed at the end of the Permian, during a period of intense volcanic activity which spewed out 10 trillion tonnes of lava.

This is thought to have increased the levels of carbon dioxide in the Earth’s atmosphere to around 8,000 parts per million (ppm), compared to roughly 425ppm today. Before long, the global temperature had spiked dramatically, disappearing thousands of species on land and in the oceans. During the Great Dying, or the Permian-Triassic mass extinction, around 90% of all life became extinct.

“So we think that the world got incredibly hot, probably the hottest it’s been for the last billion years,” says Wignall. Not only did this make survival difficult on land, but it was particularly catastrophic for aquatic life. “The effect of a really hot planet was to sort of slow down or stagnate the oceans, and so they basically lost their oxygen over a large part of the water column. Without any oxygen dissolved in the water, then things die off,” he says.

But unlike in the movies, this end-of-world event did not happen instantly. “I think when people are thinking about mass extinctions, we often go to the one that wiped out the dinosaurs… an asteroid hits the earth, vaporises everything around it, and then kicks up a dust cloud – and there’s effectively nuclear winter for a long time,” says Kammerer. The Permian extinction, on the other hand, unfolded over hundreds of thousands of years, he explains.

Now it turns out that the gorgonopsians which had originally inhabited the Karoo went quietly extinct long before the Great Dying reached its peak. Inostrancevia simply crossed Pangaea to fill the predator-sized hole that they had left behind. In the Karoo basin, Kammerer points out that ecosystems were becoming destabilised well before the main extinction pulse. Predators were going extinct, and being swiftly replaced by others. And he thinks this holds a lesson for us today: we’re further along in the extinction crisis than we might care to admit.

“One example of what we’ve already seen is here in North America, historically, we had quite a large contingent of sort of top predatory mammals, so bears, pumas and wolves,” says Kammerer. Now, in their absence, formerly mid-tier predators such as coyotes are becoming dominant. “They’re aggressively expanding their ranges, living in a lot of areas where they didn’t before and functionally, like taking over the de facto role of top predator,” he says.

In the end, even Inostrancevia didn’t make it – they vanished 251 million years ago, along with all other gorgonopsians and the vast majority of their synapsid relatives. But a handful of species did manage to cling on to existence, living to terrorise the wildlife of the Triassic.

Today, synapsid predators are still with us. Eventually, some of the survivors from the Permian extinction evolved their own central heating, fur and the ability to nourish their offspring with milk: the strange monsters of the Permian are the ancestors of all mammals alive today, including humans.

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