Did Scientists Just Unveil the Biggest Dinosaur of All Time?

Dinosaurs are superlative animals in every sense of the word. Their ranks include some of the strangest and fiercest creatures ever to have evolved, not to mention the largest to have walked the Earth. Now paleontologists have announced a species proposed to be most massive dinosaur ever discovered: an enormous herbivore estimated at over 120 feet long and weighing over 70 tons—or longer than a blue whale and heavier than a dozen African elephants.

You may have already heard of this ancient titan. The dino started making headlines back in 2014, before its bones were even fully out of the ground, getting its own David Attenborough-hosted documentary and American Museum of Natural History exhibit in early 2016. Over and over again, the Cretaceous dinosaur’s status as the biggest of all time was proclaimed. But the dinosaur didn’t have a name (it was simply referred to as “The Titanosaur”) and no formal description of the bones was published for other experts to check this sauropod’s claim for the title. 

Today, in the pages of the Proceedings of the Royal Society B, paleontologist José Carballido of the Museo Paleontológico Egidio Feruglio and colleagues have finally published the scientific details of this enormous plant-muncher.

The dinosaur’s official name is Patagotitan mayorum, meaning “the Mayo family’s Patagonian titan.” That’s because its bones were excavated in 2014 at La Flecha ranch, owned by the Mayos, in Chubut Province, Argentina, from their 101-million-year-old-resting place.

This wasn’t the resting place of just one animal. The stone was littered with the remains of at least six individual dinosaurs of different ages and sizes. By the time they were done, however, the paleontologists had excavated parts of the neck, back, tail and limbs, which were enough to come to two conclusions: This was a dinosaur no one had ever seen before, and it was a true giant.  

But was it really the largest dinosaur of all time, as some of the media hype has proclaimed? 

Not everyone is convinced. Mathew Wedel, a paleontologist at the Western University of Health Sciences who has been following the titanosaur’s story since 2014, notes that the body of the new paper doesn’t include the necessary measurements of the dinosaur’s bones to tell. On top of that, Wedel says, the measurements reported in the media so far hint that Patagotitan was comparable in size to the previous record holder, Argentinosaurus, also known from Cretaceous Argentina. 

“So not the world’s largest sauropod, probably,” Wedel says, “but the most complete super-giant sauropod by far.” This means Patagotitan joins a club of previously-discovered immense dinosaurs; its real claim to fame is that far more bones of Patagotitan are known than for other giants. “I think it would be more accurate to say that Argentinosaurus, Puertasaurus and Patagotitan are so similar in size that it is impossible for now to say which one was the largest,” Wedel says. 

But step back from the “my dinosaur is bigger than yours” contest for a moment, and a curious pattern starts to appear. “All the big sauropods for which we have good evidence seem to be clustering in the same general area,” Wedel says, whether those are titanosaurs or other sauropod giants from different lineages. “That suggests a real upper limit that all these lineages were hitting,” Wedel says, with Patagotitan not so much blowing past previous records as reinforcing an emerging pattern.

Which brings us to the question of why these dinosaurs got so large at all. Macalester College paleontologist Kristi Curry Rogers points out that these huge sauropods were bellwethers of the times they lived in. “Titanosaurs like Patagotitan evolved huge bodies because they could,” Curry Rogers says, adding that “the ecosystems they inhabited had the resources to support their bodies, and their unique and specialized physiological adaptations made behemoth sizes work for them.”

 Furthermore, Wedel says, a giant like Patagotitan “is a case of ‘them that has, gets.’” 

Living large has definite benefits. Big sauropods, Wedel says, laid more eggs, were harder for predators to kill, could survive on lower quality food, could migrate long distances on less resources, and more. The bigger they got, the more benefits they reaped: “So to me the mystery is not ‘Why did some sauropods get so big?’; it’s “Why didn’t all sauropods gets big at Argentinosaurus, Puretasaurus and Patagotitan?’” Sauropods came in sizes from about as large as a draft horse to the biggest animals on land. What led to that range of sizes is still unclear. 

Yet for better or worse, it’s the giants who transfix our attention, and it seems that every few years there’s another dinosaur that’s touted as the largest of all time. Brachiosaurus, Supersaurus, “Seismosaurus”, Argentinosaurus and more have all had their turn laying claim to the title over the years. 

Could there still be larger dinosaurs out there? Curry Rogers thinks so. “So far, all of the very biggest sauropod dinosaurs how clear signs that they are still growing” when they died, Curry Rogers says. Even the largest Patagotitan bones, she points out, show signs of ongoing growth at death. “Even if we’ve discovered the largest terrestrial animals ever known,” Curry Rogers says, “we haven’t found the biggest representatives of their species so far.”

So rest assured, paleo-lovers: There are still giant discoveries to be made. 

Riley Black | | READ MORE

Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Scientific American.