Millions of years ago, Earth was ruled by giants. Pterosaurs with 12m wingspans darkened the skies, dragonflies the size of widescreen televisions buzzed among the undergrowth and sauropods the length of a jumbo jet browsed the treetops.
And there was one that was probably bigger than them all: the Cretaceous colossus that was the dinosaur Patagotitan mayorum, whose replica skeleton currently fills the Waterhouse Gallery at the Natural History Museum.
How big was Patagotitan?
Clocking up some 57 tonnes in weight and measuring 37m from nose to tail, Patagotitan is the largest, most complete dinosaur currently known.
What dinosaur family did Patagotitan belong to?
Patagotitan was a member of the titanosaur family, in turn part of the wider sauropod group known for their immensely long necks and thick, squat limbs. Diplodocus was a sauropod, as was Brachiosaurus – the gentle creature we see feeding from the canopy in that captivating scene in Jurassic Park.
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When was Patagotitan discovered?
But while we’ve known about ‘Dippy’ and Brachiosaurus for more than a century, Patagotitan was only discovered in 2010, hot on the hefty heels of many other new titans, such as Puertasaurus (2001), Dreadnoughtus (2005) and Argentinosaurus (1987).
Indeed, we are currently experiencing something of a golden age of dinosaur discovery. An average of 50 new species are being added to the tally each year, with a current running total of about 700 (and counting). The boom has been driven by two main factors.
“There are now many more people working on dinosaurs in countries in South America, Africa and Asia, which didn’t have palaeontologists before,” says Paul Barrett, dinosaur specialist at the Natural History Museum in London. “These locations are naturally rich in fossil remains, so the rate of discovery is going up. We’re also finding new species by re-assessing existing collections. In my time at the Museum, we’ve discovered about 10 new species from material that hadn’t yet been worked on or had been misidentified.”
Where was Patagotitan found?
Patagotitan, though, hailed not from a dusty basdiniement but from the remote badlands of Argentinian Patagonia. He didn’t know it then, but when farm worker Aurelio Hernandez spotted a thumping great femur sticking out of the ground near La Flecha, he had chanced upon the 101-million-year-old remains of the largest animal ever to have walked the Earth.
Not only that, there were six of them, a small herd that had likely succumbed to a natural catastrophe. “Patagonia is rich in dinosaur fossils as the geography is right,” says Paul. “It’s sparsely vegetated with fast-eroding rocks at the surface, which are constantly whittled away by the snow, wind and rain. There’s no fancy technology to fossil-hunting – you just go out and look at the ground a lot.”
It took three painstaking digs over five years to excavate the remains, and it didn’t take long for the palaeontologists to realise that they were uncovering a new species.
The sheer abundance of bones – more than 200 of them – gave more insight than ever before about a titanosaur, enabling the scientists to create its replica skeleton and issue its vital statistics with a substantial degree of accuracy. “Estimates of weight inferred from partial skeletons tend to be very rough with wide error margins, which is why a lot of figures come down as more research is carried out,” says Paul. “But with Patagotitan we are much more confident.”
It’s quite something, rounding a corner to suddenly find a titanosaur looming over you. The long, winding neck, composed of a series of neatly interlocking vertebrae, stretches upwards and outwards; its ribs dangle like enormous flattened fingers a few feet above head-height, its tail snakes out of sight around a pillar.
Standing underneath it, I wonder how, if caught in a stampede, I might avoid being crushed like a tin can. But would such a big creature have even been capable of running? And what about eating, drinking, sleeping, fighting and – gulp – breeding? In short, how on earth did Patagotitan function?
Why were titanosaurs so big?
Many dinosaurs were of significant size, but why titanosaurs should go a stage further and end up almost twice the size of your average big dinosaur is not fully understood.
“There might have been something unusual about the climate, the environment or the plants in Patagonia, where most of these giants come from, at the time,” says Paul, “but so far we’ve not found anything particularly odd about that area compared to other parts of the world where long-necked dinosaurs lived, but didn’t reach these colossal sizes. It’s a mystery.”
Sauropods, which are large in general, probably acquired their size as an adaptation to their diet. They were vegetarians, feeding on plants that were hard to digest and not particularly nutritious. “The best way of making a living on that diet is to be large,” says Paul. “You effectively turn yourself into a giant fermentation tank – you eat lots of food and give it time to pass through a very long gut, which means you can extract the most from it.”
What did Patagotitan eat?
You can see how Patagotitan was adapted to lunching on leaves. Its 40-ish widely spaced, peg-like teeth, which bear a passing resemblance to cocktail sausages, are a far cry from the steely, pointed gnashers of a T-rex. All the better, though, for raking huge mouthfuls of vegetation from the treetops and swallowing them whole.
Requiring 120kg of food per day (the equivalent of 516 iceberg lettuces) merely to keep ticking over, stripping trees was probably how your average Patagotitan spent its day, utilising its long and flexible neck to both browse the canopy and lap water from the ground. Dinosaurs largely lived before grasses evolved, so its landscape would have comprised a rich coniferous forest characterised by trees such as Araucaria (monkey puzzle) and Fitzroya, with undergrowth dominated by ferns and horsetails. Anything this giant consumed took ten days to emerge from the other end.
Patagotitan moved in herds, its large legs enabling it to access pastures new in the event of a local drought or wildfire. “As they travelled and fed, they would have played a key role in shaping their world – we think they were ecosystem engineers,” says exhibition lead Sinéad Marron. “Like today’s forest elephants, they would have churned up the ground, created space for new growth and regenerated the forest with their seed-rich dung.”
Living it large not only requires an awful lot of lettuce, but an incredibly fast growth-rate. By the age of two months, a baby Patagotitan had already soared to ten times its hatchling weight, putting humans, who take a decade to reach a similar milestone, to shame. “It blows my mind how small these titanosaurs start out in life,” says Sinéad. “They hatched from melon-sized eggs as mini versions of the adults, and within 30 years had grown 16,000 times bigger.”
How did Patagotitan reproduce?
From studies of their close relatives, it’s thought that Patagotitan laid clutches of 30-40 eggs in scrapes in the ground, possibly covered in a layer of soil or leaves, and left them to it. They weren’t particularly doting parents, but to be fair, they didn’t have much choice. “An animal this large can’t incubate its eggs – they’d become a giant omelette,” says Paul. “But there is evidence that females laid eggs in volcanic soil, using the geothermal heat to keep them warm.”
Like baby turtles on tropical beaches, the hatchlings had to make a dash for it, running a gauntlet of predators to seek shelter. Only one in 100 survived to adulthood, rather unfavourable odds that the parents countered by producing several hundred eggs each year. At least with such a fast growth-rate, any youngster that did make it could accelerate through the most vulnerable stages of life.
How did Patagotitan cope with being so big?
Whether bigger is better is up for debate: a supersized life brings supersized challenges when it comes to the physical limitations of biological material. At the end of the day, a titanosaur is a living thing composed of flesh, blood, bone and organs, all of which must operate at this extensive scale and under the force of gravity. The main difficulties Patagotitan encountered were supporting its weight and fulfilling its huge energy demands. But it had a number of tricks up its (substantial) sleeve.
What did Patagotitan look like?
First, there was its basic design. In classic sauropod style, Patagotitan sported four sturdy, columnar legs to carry its bulk (in contrast to, for instance, the bent legs of the small, fast-running velociraptor), and a long neck and tail that spread the load like a suspension bridge. It also had a sophisticated breathing system involving a series of air sacs spread throughout its body, even into its bones, rendering them conveniently lightweight. Its lengthy neck and naked skin helped to dump the heat radiated by its constant muscle and digestive activity, and, of course, it had that fermentation tank of a gut.
Were Patagotitan intelligent?
If there’s one part of Patagotitan that bucks the trend to be big, it’s the brain. At roughly the size of a grapefruit, it’s surprisingly small for such a giant. “These animals are not winning any quizzes,” says Paul. “We deem intelligence as important, but most animals aren’t – they just need to eat, make babies and avoid predators.” Patagotitan probably wasn’t a particularly complex creature, but frankly, it was the size of nine London fire engines, so who cares?
Did Patagotitan have any predators?
In any case, Patagotitan didn’t really have to worry about predators. An adult in its prime would have simply been too big for even the largest and most ferocious carnivores of the Cretaceous to overcome. Even Tyrannotitan (pictured below) – a 12m, T-rex-like predator that would have been as terrifying as it was impressive – was just one tenth the size of Patagotitan.
One butt-barge or shoulder-shove from its quarry and it would fall and possibly break an ankle, a risk that outweighed the reward. If it fancied titanosaur for tea, Tyrannotitan focussed its efforts on the young or the sick, or scavenged the carcasses of the dead – as evidenced by the many fossil teeth rattling around in Patagonia’s mass grave.
Statistically, we’ve another 25 or so dinosaurs to discover before the end of the year. Could Patagotitan be bumped from the prehistoric podium? “Never say never, but I think we’re near a ceiling,” says Paul. “They’re pushing at what it’s possible to do with a body on land. We could perhaps go a few tonnes more, though I’d be surprised if we find anything significantly bigger.”
But Patagotitan is plenty large enough for now. It’s incredible to think that this giant once walked the Earth.
Titanosaur: Life as the biggest dinosaur is on at the Natural History Museum, London until 7th Jan 2024. Adult tickets start at £16.
