Matt dug in Patagonia. He made a priceless discovery about Earth’s biggest creatures

He disappears into the museum’s backstage collection, which holds 42,000 fossils, and I am left manhandling a sauropod egg the size of a soccer ball. Its hatchling couldn’t have been much larger than a chihuahua. And yet, from eggs such as this one emerged babies that swelled to the size of buildings in just 15–20 years. The phenomenal growth rate makes sense, given the goal was to spend as little time as possible with a body small enough to fit between a predator’s jaws.

About 60 Tyrannotitan teeth were found alongside the six Patagotitan specimens Carballido famously unearthed between 2012 and ’15 with colleague Dr Diego Pol. Initially, due to bite marks on the sauropod’s tail, they believed the Patagotitans had been killed by the carnivores. Histological analysis, however, showed the sauropods were young adults, still growing but already the size of semitrailers and too large for Tyrannotitan’s jaws.

At that size, only one dinosaur could have posed a threat: another Patagotitan. “They were at the age and at the moment of the year when males fight each other to be the dominant one of the group,” Carballido speculates. “Probably, the specimens that we found were those who lost the fight.”

Those Tyrannotitan teeth, then, may have been the result of a scavenging smorgasbord rather than an active kill.

At a similar time to Patagotitan rose Argentinosaurus – believed to be even bigger, but it’s hard to say unequivocally given we only have a handful of their bones. At another site, Carballido is excavating the bones of another new titanosaur that may be 5 to 7 per cent bigger again. Something about this time period, the “Albian” age between about 100 to 113 million years ago, made the gigantic possible.

The biggest titanosaurs also only occurred in a restricted band of the mid-latitudes, far from the equator. Carballido believes tropical forests may have been too hot for the giants. McCurry is pondering another theory he’s keen to discuss with paleobotanists: that the latitudes titanosaurs occupied had uniquely phosphorus-rich vegetation, which acted like fertiliser for their fast-growing bones.

Titanosaurs shrank towards the end of the dinosaurs’ reign into species such as Saltasaurus, which grew to 8.5 metres and weighed only 2.5 tonnes; positively pocket-sized, by sauropod standards. The trend violates an idea called Cope’s law. “The idea with Cope’s law is that everything gets bigger through time until there is an extinction event,” McCurry says. “But it’s not the case with sauropods. It seems like it’s happening in a peak during the middle Cretaceous.”

The exact factors behind the giants’ rise and fall remain under scrutiny. But you needed it all for biology to achieve its grandest, meatiest megalith: the perfect climate, ideal latitude, lush vegetation and ferocious predators. Kaboom. Patagotitan.

The new sauropod bones excavated by McCurry and Carballido are spread across the institute’s laboratory, a dusty workshop strewn with bloodthirsty-looking skulls, buckets of ribs and boulder-sized fossils that could crush a Corolla. It’s a place that shows the study of dinosaurs remains a hotbed of discovery. A new dinosaur species is coming from the earth once a week, and cutting-edge technologies are pushing the limits of what fossils can teach us.

We learned only recently from preserved pigment structures that Diplodocus sauropods had sensationally speckled skin, and Australian-led research out this month has uncovered fossilised red blood cells in the 115 million-year-old bones of a Brazilian feathered theropod.

Carballido hands over a chevron bone, a Y-shaped structure the length of my forearm and shaped like a crude slingshot, that would’ve carried a rope-like vein down the sauropod’s tail. In a crate nearby are two caudal vertebrae – almighty slabs of the beast’s tail – and its clublike femur, all bound for display in Sydney. The sacrum of the new species lies in the centre of it all, splayed open and demanding reverence like the eldritch slab of an ancient altar.

Over the next week, McCurry and Carballido painstakingly code every bump, curve and knob of these bones and feed the numbers into a phylogenetic character matrix, which converts morphological elements of a skeleton into code. By comparing the matrix to other Gondwanan sauropod species from both Australia and South America, they can calculate where a new species fits on an evolutionary tree.

What they have discovered is not just a primitive Patagotitan relative. They suspect this dinosaur marks the first branch on the evolutionary tree that led to titanosaurs. The critical opening chapter in the odyssey of biology’s grandest juggernauts.

“We need to get a little bit more data into the phylogeny to have it for certain,” McCurry says when we meet up in Buenos Aires after his week of rapid analysis at MEF. “But it’s looking good. There’s all these characters within the pelvis which show it’s probably got quite a wide stance, which is a pretty characteristic titanosaur thing.

It’s potentially one of the reasons they were able to feed really efficiently, because they had a large area for their internal organs and stomach.” That wide stance allowed for the sauropod’s engine – the fermentation tank of its gut – to grow fat and supercharged, so it could slowly strip every iota of nutrition from vast amounts of vegetation it gorged upon from the top of the canopy. “It means titanosaurs, when they first evolved, had these traits.

And we didn’t necessarily know that.”

Before the palaeontologists can name and describe the new species, they must recover the rest of the fossil. At least a scapula and a humerus remain buried. But funding such expeditions, of late, has been difficult.

In Buenos Aires, a few days after visiting Chubut, traffic is at a crawl. We inch past a protest on the edge of detonation: soon rocks will fly and police will return fire with tear gas, water cannons and rubber bullets. The demonstrators are raging against right-wing populist President Javier Milei’s cuts to universities and education. Science funding in Argentina has plummeted by 50 per cent since 2023. Professors’ pay has plunged below the poverty line and world-class experts, such as Carballido, have found themselves kneecapped with little funding for fieldwork.

Meanwhile, Australia’s premier science body, the Academy of Science, has been up in arms over the fact that spending on research and development has crashed to the historic low of 1.69 per cent of GDP, below the 2.7 per cent average among OECD nations.

That’s forced researchers of all stripes to get creative. McCurry and Carballido, for their part, are gunning for funding from the Department of Foreign Affairs and Trade, which operates a diplomatic grants program called the Council on Australia Latin America Relations (COALAR). The idea is to run more joint expeditions, cross-pollinating Australia’s analytical know-how with the expertise of Patagonia’s field technicians – and hopefully fund the rest of the sauropod dig on the side.

In Chubut, times in the province are tough as the profits of traditional industries, including sheep farming, wane. Amid the downturn, the paleontology museum has become a beacon of tourism and economic activity, and the institution’s regional city of Trelew has embraced the dinosaur theme with gusto.

A mock fossil site decorates the walls of the baggage claim at the airport and a model raptor snarls in a corner. Walk outside the arrivals hall and on the steppe’s flat, dry horizon, you’ll spy a looming model Patagotitan. Stand beneath it and you can imagine a primordial mammalian part of you quivering with the memory of scuttling around the feet of giants. All around, the Patagonian wind blows, spiriting away sand and time to offer the bones of gods to the air.

Angus Dalton and Louise Kennerley travelled to Patagonia courtesy of the Australian Museum and Adventure World. Dinosaurs of Patagonia opens on November 28.

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