Paleontologists rarely discover a complete skeleton . It is something quite complicated; they will most likely find bone fragments and then try to estimate a height and weight profile. To complicate matters further, there are three categories to define the largest dinosaur on record: the heaviest, the longest, and the tallest.
The heaviest dinosaur
Starting with the weight, the winner of the gold medal is probably the Argentinosaurus. This supermassive, long-necked, long-tailed herbivorous titanosaur lived about 100 million – 93 million years ago, during the Cretaceous period, in the Cenomanian, in what is now Argentina.
But estimates of Argentinosaurus’ weight vary widely: the beast weighed 77 tons, according to the Natural History Museum in London; up to 90 tons, according to the American Museum of Natural History in New York City; and 110 tons, according to BBC Earth.
It is not surprising that the figures dance so much and it is that we only know the Argentinosaurus from 13 bones: six medium vertebrae, five fragmented hip vertebrae, a tibia and a rib fragment.
Another contender is Patagotitan mayorum , a titanosaur that weighed a whopping 69 tons when it lived about 100 million years ago in what is now Argentina. However, this weight was calculated based on six individuals in total, rather than just one dinosaur. The Patagotitan was 40 meters long and 20 meters high and its remains were found in Chubut.
The longest dinosaur
This honor can probably go to Diplodocus or Mamenchisaurus, which can be described as thin and elongated sauropod dinosaurs. In this case, both are known from reasonably complete skeletons, and both would be approximately 35 meters long.
In contrast, titanosaurs were shorter. For example, Dreadnoughtus schrani was “only” 26 meters long.
However, we return to the problem of the fossils found. Some dinosaurs that are claimed to be the longest are barely counted with remains; for example, Sauroposeidon proteles is considered a very long dinosaur, but only four neck vertebrae have been found. It’s the same as Amphicoelias , a sauropod known only from a sketch of a single vertebra in a notebook by 19th-century paleontologist Edward Cope. This sauropod, precisely, is often cited as the longest, tallest and heaviest dinosaur that has ever walked on the face of the Earth.
Tallest Dinosaur
As for the tallest dinosaur, the winner is probably Giraffatitan brancai a 12-meter-tall sauropod dinosaur that lived in the late Jurassic some 150 million years ago in what is now Tanzania. As for the actual height of that dinosaur, who knows. The key is to find a complete fossil, something that, as we have seen, is very difficult to locate.
