Scientists believe a dinosaur the length of three London buses could be the largest creature to have ever walked the Earth.
A study of the fossilised remains of six young adult dinosaurs found in Argentina estimates the Patagotitan mayorum had a body mass of a staggering 61 tons, was 35m (115ft) long and was nearly 6m (20ft) high at the shoulder.
It means the giant creature was longer than three of the capital's new Routemaster buses, weighed more than some Boeing 737 aircraft, and was as tall as a male giraffe at its shoulder.
Classed as part of a group of large dinosaurs called titanosaurs, the Patagotitan mayorum is believed to have lived 100 million years ago during the Cretaceous period.
As a sauropod, it would been a plant-eater that stood on four legs with a long tail and neck.
An artist's impression of the Patagotitan mayorum
The fossils, including vertebrae and rib bones, were found at a quarry in Chubut Province in Argentina's Patagonia region in 2013.
The discovery of six different individuals together, believed to have died in a floodplain region before being preserved in mud, is the first indication that titanosaurs engaged in social activity.
Writing in the journal Proceedings of the Royal Society B, researchers led by Dr Jose Carballido, from the Museo Paleontologico Egidio Feruglio in Argentina, have now described the Patagotitan mayorum as "the largest known dinosaur species".
The remains of six young adult dinosaurs were studied by researchers
Although the Argentinosaurus has previously been handed the title of biggest land animal ever, estimates of its body mass of 79 tons were not based on limb measurements and may be unreliable.
The researchers said vertebrae from Argentinosaurus suggest it was 10% smaller than Patagotitan mayorum.
It is believed the Patagotitan mayorum was able to get so massive due to an explosion of flowering plants at the time it lived.
Study co-author Diego Pol said: "I don't think they were scary at all. They were probably massive slow-moving animals.
"Getting up. Walking around. Trying to run. It's really challenging for large animals."
He suggested carnivorous Tyrannosaurus rex dinosaurs would "look like dwarfs when you put them against one of these giant titanosaurs", adding: "It's like when you put an elephant by a lion."
University of Maryland palaeontologist Thomas Holtz, who was not part of the study, said: "It's hard to argue this isn't a big deal when it concerns the (probable) largest land animal ever discovered."
Other researchers suggested the fact the fossils were of not fully mature adults points to there being even bigger dinosaur bones left to discover.