Have You Met the Most Massive Dinosaurs to Ever Roam the Earth?

Supersaurus vivianae was one of the longesnosaurs. Scientists estimate it reached up to 34 metres from its nose to the tip of its tail, based on its spinal bones.

But what seems to be the tallest dinosaur is Sauroposeidon proteles, a massive plant-eater discovered in North America, and stood at an impressive 17 metres, though relatively few fossils of it have been found. Its estimated height is largely based on the more complete remains of Giraffatitan brancai, which at a time held the “biggest dinosaur” title.

The heaviest known dinosaur is currently Argentinosaurus, whose fossils were found in the Patagonia region of Argentina, hence the name. It is estimated that its weight ranged between 60 and 100 tonnes, but the precise weight is unknown because the fossils are so limited.

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The new contender for the heaviest, tallest, and longest dinosaur is a titanosaur, meaning it belongs to the same group as Argentinosaurus. So far, the fossil record for titanosaurs has been sketchy, with just a few enormous fossils found to hint at their overall size. They have been known for quite a while, but they have generally not been a very well-understood group of dinosaurs.

The thigh bones recovered from the site are taller than a man. Experts from the Museum of Paleontology Egidio Feruglio, Argentina, say this suggests the creature stood as tall as 5.8m (19 ft) at the shoulder. The circumference of the thigh bones and a forelimb imply that it weighed around 70 tonnes.

It was likely to have been 40m (131 ft) long. Unfortunately, despite an impressive haul of 223 bones from seven animals, experts have not found a skull. Instead, they examined the skulls of other titanosaurs, only three of which have been found so far, to reconstruct the animal.

Preliminary estimates say the newly discovered titan is 10% larger than the former heavyweight champion, that is, the Argentinosaurus. The most complete titanosaur skeleton currently known to science belongs to Dreadnoughtus schrani, first described in 2014 by Kenneth Lacovara of Drexel University, Philadelphia and colleagues. Till date, 116 bones have been found, out of an estimated 256.

The original estimates suggested D. schrani could have weighed up to 60 tonnes. But a 2015 study downsized it to between 20 to 25 tonnes. But not only D. Schranis have been downsized. What were once known as the biggest dinosaurs of all time, the Brachiosaurus – long-necked sauropods featured in the original Jurassic Park,  once thought to weigh 80 tonnes – a great over-estimation – were down-sized, with most estimates putting them down to 50 tonnes or lower.

The reason for this is because the traditional method for determining the proportions of dinosaurs depended on measuring the circumference of leg bones, because paleontologists believe that there is a relationship between the circumference of these animals’ bones and their weight.

But the latest technique, known as convex hulling, relies on computer modelling. Using this  technique, researchers scan each bone to create a virtual model of the dinosaur. If the skeleton is incomplete, the gaps are filled with parts based on related dinosaurs.

The model is then filled with organs, wrapped in muscle and covered in skin, all of which are based on lizards, birds and crocodiles alive today. Experts can then calculate the weight of the dinosaur. This process can fine-tune previous estimates, which is how dinosaurs, previously thought to be the heaviest suffered their drastic weight loss.

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One member of the team, Diego Pol, says they have 70% of the skeleton, which should make their estimates pretty accurate. But until it is formally described in a peer-reviewed journal, the nameless titan cannot knock Argentinosaurus off the top spot. Though, he admits that the titanosaur he is studying was not fully grown when it died, holding out much hope for the possibility of this family of dinosaurs being the largest.

Pol’s findings suggest the anonymous giant may have had some margin to develop. Only an adult fossil will confirm this, so even bigger titanosaurs may be seen in years to come.

From BBC Earth