There’s a new big dino on the block — and it makes even the mighty T. rex look like a poodle.

Skeleton cast (left-center) and fossils (far right) on display at the American Museum of Natural History, New York.
Image credits Editosaurus / Wikimedia.

Back in 2012, archaeologists digging in southern Argentina unearthed a massive set of fossilized dinosaur bones. Fossils which, according to a newly published paper, belonged to the biggest big dinosaur — the largest titanosaur and largest animal that ever roamed the Earth.

“There was one small part of the family that went crazy on size,” said study co-author Diego Pol of the Egidio Feruglio paleontology museum in Argentina.

While it is part of the titanosaur family, the dino is part of a whole new species and genus, meaning the team had to give it a name. They christened the beast Patagotitan mayorum, for the region where it was discovered (Patagonia) and the Greek work “titan” which, you’ll never guess, means ‘large’. The team chose the second name in honor of a rancher family that housed them during their excavations.

But let’s talk dinosaur

The researchers recovered and studied six fossils of the new species. They’re estimated to be about 100 million years old, based on the dating of ash formations buried alongside the fossils. But what truly sets these plant-eating dinos apart is their monumental size — the team estimates that P. mayorum averaged about 37 meters (122 feet) in length and grew to 6 meters (20 feet) in height at the shoulder. It’s so big that when the American Museum of Natural History, New York got a cast of the bones to display, they had to install it with the head sticking out into a hallway from the main room.

Size comparison to a human.
Image credits CHUCAO / Wikimedia.

Based on these proportions, the beast likely weighed about 76 tons — to put that into perspective, the Space Shuttle only weighed about 74.8 tons. You could stack 12 African elephants on top of the other and mayorum would still likely outweigh them. So it’s not hard to see why Pol says T. rex and other predatory dinos “look like dwarfs when you put them against one of these giant titanosaurs.” Thus, P. mayorum took the mantle of biggest ever known dinosaur, previously held by another titanosaur called Argentinosaurus.

But for all their size, they were likely very peaceful creatures.

“I don’t think they were scary at all,” Pol said. “They were probably massive big slow-moving animals.”

“Getting up. Walking around. Trying to run. It’s really challenging for large animals.”

The question now, however, is how and why these animals grew to such proportions. One theory is that the explosion in plant life in the Cretaceous period meant that these animals had a virtually endless source of food — so they just kept growing larger and larger.

This theory also raises another very exciting prospect: there may be dinosaurs out there that out-grew even Patagotitan mayorum’s monumental scale. We just need to find their bones.

The paper “A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs” has been published in the journal Proceedings of the Royal Society B.