The study group, from Drexel University, Philadelphia, US, say they have 70% of the key bones needed to fully describe the creature, Dreadnoughtus schrani.
From the evidence, they estimate the huge creature measured 26m from head to tail, the size of two London buses front to back, and weighed in at almost 60 tonnes.
The skeletal analysis reveals Dreadnoughtus was still growing at the time of its death. They can't estimate how large the dino might have become. The Patagonian rocks surrounding the bones suggest that the young animal's life was cut short in a catastrophic flood.
The study group's leader told the BBC that the dinosaur's enormous size would have been intimidating.
For that reason, he named the beast after the massive battleships that revolutionized naval warfare in the early 1900s. The first really big steel battleships were impervious to attack from other existing ships at that time.
The newest exciting find of Dreadnoughtus was one of the so-called titanosaurs dinosaurs. Although its skull has not survived, almost half of the rest of the skeleton has been preserved. As a result, Dreadnoughtus offers an unprecedented window into the anatomy, biomechanics and evolution of the titanosaurs.
These supermassive, plant-eating dinos were the most massive beasts ever to plod the Earth's land surface. Just imagine how much fodder the massive body would need to eat. See full BBC story with fantastic pictures here.
Giant dinosaurs stir children's imagination. But just imagine meeting one out on your walk. Trampling buildings or knocking down huge trees in the park. No. There's no pace left on Earth for the relics now. It's hard enough for elephants to find somewhere to roam.
Lately people have been increasing in size. We eat so well, there's no stopping us. Even old gentlemen's hats found at second-hand stores are way too small for the modern head. Maybe mankind will outgrow the planet too.
I grew taller than my mother, and the same for her and her mother. My son was six feet five inches. So in order from my grandmother to my son: 5'2”, 5'7”, 5'10”, 6'5”.
What about your family?