We all know that many dinosaurs are huge, but which one of them is the biggest?

Determining the biggest dinosaur to have ever walked the earth is no easy task. Paleontologists have to work on incomplete specimens and make educated guesses to estimate their size and reconstruct their appearance. 

There are cases where very few bones of a certain specimen are found and they won’t be enough to reconstruct the dinosaur. What paleontologists do is compare them to more extensive remains of other dinosaurs of the same family to estimate the size of the specimen. 

In recent years, advanced 3D modelling software has greatly helped paleontologists in figuring out the size and appearance of dinosaurs. However, this does not mean that more advanced technology would end all the unvertainty around the estimated size of the dinosaur in question.

When we talk of “big”, we also have to qualify the parameters. Are we talking of the weight, the height, or the length? 

All of the gargantuan dinosaurs competing for the top spots for the heaviest, tallest, and longest dinosaur belonged to a group of dinosaurs called the sauropods. These were four-legged herbivores that had long necks and tails, and relatively small skulls and brains.

The heaviest dinosaurs

It's the clash of the titans for the heaviest dinosaurs, with the both contenders belonging to a group of sauropod dinosaurs called titanosaurs. 

The Argentinosaurus


The Argentinosaurus was a member of a group of dinosaurs called Titanosauria composed of dominant sauropods. It lived during the Late Cretaceous period in what is now part of Argentina.

Argentinosaurus was widely considered the heaviest dinosaur for the longest time. Very few bones of this dinosaur were found. A calf bone was found by a farmer in 1987. Years later, excavation on the same site yielded some vertebrae and ribs which were determined to belong to an individual dinosaur. This individual was later identified as a new species and named Argentinosaurus (Argentine lizard).

To estimate the size of the Argentinosaurus, paleontologists compared one neck vertebra, which was 1.59 metres long with the vertebrae of more complete sauropods that have been previously found like the Saltasaurus and Rapetosaurus

The Argentinosaurus was estimated to be 37 to 40 metres long and thought to have weighed up to 100 tonnes but the most recent estimate is between 60 to 90 tonnes. 

The Patagotitan 

The Patagotitan is the newest contender to the heavyweight title. Discovered fairly recently in 2012 and formally named only in 2017, the Patagotitan was also a member of the titanosauria group of dinosaurs. They lived 100 million to 95 million years ago.

Paleontologists found partial skeletons of at least seven individuals in Patagonia, Argentina. The bones were more complete compared to that of the Argentinosaurus. One of the bones found was a femur that measured 2.4 metres long.

Based on the partial skeletons, Patagotitan is estimated to have measured 37.2 metres long and weighed approximately 70 tonnes. Some paleontologists believe these figures were overestimated. 

The tallest dinosaurs

The Sauroposeidon


The Sauroposeidon is a sauropod that lived during the Early Cretaceous period. It was only known from the four neck vertebrae that were found in South-eastern Oklahoma. The largest vertebra found from this dig measured 1.4 metres.

Based on the comparison on the specimen of the Giraffatitan brancai, another contender for the title, the Sauroposeidon is estimated to have been as tall as 18 metres with its neck estimated to be 11.2 to 12 metres.

The Giraffatitan

Giraffatitan Dinosaurs

The Giraffatitan was a plant-eating sauropod dinosaur that lived in the Late Jurassic period. It was so named because it bore resemblance to the giraffe: it had a long neck and its forelimbs were longer than the hind limbs.

Based on the skeletons of the specimen, the Giraffatitan is estimated to be 12 metres tall. 

The longest dinosaurs

The Argentinosaurus and the Patagotitan would also be contenders in this category. But here are the other dinosaurs that compete for the spot.

The Diplodocus

Diplodocus dinosaur

The Diplodocus lived during the Late Jurassic period around 155 to 157 million years ago in what is now the western part of North America.

This dino is not necessarily the longest dinosaur ever known, but it is the longest dinosaur known from a near-complete skeleton.

Four species of Diplodocus are recognised: D. carnegii, D. hallorum, D. hayi and D. longus. Of the four, D. hallorum is considered the largest measuring around 33 metres long from head to tail. 

The Supersaurus

The Supersaurus (super lizard) lived in the Late Jurassic period in what is now North America. Its estimated length was 33 to 34 metres. 

The Maraapunisaurus

The Maraapunisaurus was originally assigned as a species of the genus Amphicoelias (A. fragillimus) but was later on designated as a separate genus. It lived during the Late Jurassic period in what is now western part of North America. 

Its estimated length is between 40 to 60 metres making it the longest dinosaur to have ever been found. However, the estimate was only based on the surviving description of a single fossil bone. The fossil itself eventually got lost after being studied and described. 

The first estimate is also being disputed by some paleontologists who say that a more accurate estimate is around 30 to 40 metres in length. 

Other big dinosaurs

The biggest dinosaurs were herbivorous sauropods. How about the dinosaurs from other groups? How did they fare in the battle of the giants?

The biggest carnivorous dinosaur

The Spinosaurus (spine lizard) was the largest of the carnivorous dinosaurs trumping the Tyrannosaurus and Giganotosaurus. It lived during the Cretaceous period in what is now North Africa. This dinosaur had long spines of up to 2.1 metres long that grew out of its vertebrae forming a sail on its back, hence its name. 

Spinosaurus and Psittacosaurus Dinosaurs

Some paleontologists estimate that the Spinosaurus was 16 to 18 metres long and weighed around 7 to 9 tonnes. Others estimate that this dinosaur was 12.6 to 14 metres long and weighed between 12 to 20 tonnes. 

The largest ceratopsid (horned and frilled dinosaurs)

The ceratopsids were a family of quadrupedal herbivores characterised by their horns, frills, and beak-like mouths. 

The Eotriceratops is most likely the biggest (heaviest) ceratopsid. It is estimated to be 8.5 metres in length and weighed 10 tonnes. It lived during the Late Cretaceous period in the area of North America. The Triceratops, and Titanonceratops are close runners-up.

The largest bird-mimic-dinosaurs

The ornithomimosaurs ("bird-mimic lizards") are theropod dinosaurs with a resemblance to the modern-day ostrich. 

The largest ornithomimosaur is the Deinocheirus (terrible hands). It was so named because for 50 years, it was only known through a pair of arm bones measuring 2.4 metres long, each having three 20-centimetre claws. Two well preserved specimens of the dinosaur were found decades later. 


The Deinocheirus lived during the Late Cretaceous period around 70 million years ago in what is now part of Mongolia. It is estimated to be 11 metres long and weighed around 6 tonnes.