Top 10 Largest Dinosaurs in History: Which Was the Biggest?

Quick Answer

Under ScaleCheck's current comparison criteria, the #1 largest dinosaur in history is Argentinosaurus.
Its representative body mass is estimated at approximately 70 tons, with a body length of around 35 m.

However, the longest dinosaur and the heaviest dinosaur are not necessarily the same. The runner-up, Patagotitan, weighs approximately 57 tons but measures 37.5 m in length, making it longer than Argentinosaurus in this list. This ranking is based on estimated representative body mass derived from fossils, rather than total body length.

Dinosaur sizes are not direct measurements taken from living specimens. Because estimates can vary depending on the completeness of fossil remains and reconstruction methods, the figures below should be viewed as representative values based on current data rather than absolute records.

Placed Side by Side with Familiar Objects

Numbers like 30 to 37 m are difficult to intuitively grasp. Placing super-giant dinosaurs side by side with an adult human and a city bus makes their immense scale much easier to imagine.

The body length of a single Argentinosaurus alone is comparable to lining up more than three city buses end to end. However, because complete skeletons are rarely discovered for such colossal dinosaurs, it is difficult to determine precise sizes based solely on length alone.

Top 10 Largest Dinosaurs in History

In ScaleCheck, rankings were established based on estimated representative adult body mass. In cases of equal body mass, body length and fossil completeness were considered together.

#1 Argentinosaurus — Approx. 70 Tons

Ecological reconstruction of Argentinosaurus Argentinosaurus huinculensis is estimated at approximately 70 tons and 35 m in length, making it the heaviest dinosaur on this list.
Although size estimates carry a wide margin of error because discovered fossils consist of only a few vertebrae and limb bones, it remains an indispensable prime candidate when discussing the heaviest dinosaur in history.

#2 Patagotitan — Approx. 57 Tons

Ecological reconstruction of Patagotitan

Patagotitan mayorum is estimated at approximately 57 tons and 37.5 m in length, boasting the longest body length in this list.
Crucially, hundreds of fossil bones belonging to at least six individuals have been discovered, allowing scientists to reconstruct its body shape and size with relatively high reliability compared to other super-giant dinosaurs.

#3 Puertasaurus — Approx. 50 Tons

Skeletal reconstruction of Puertasaurus Puertasaurus reuili is estimated at approximately 50 tons and 30 m in length.
However, because the known fossils consist of only four vertebrae, size estimates for this dinosaur carry particularly high uncertainty.
The discovered dorsal vertebrae were extraordinarily wide, suggesting it possessed an immense rib cage and a broad torso during life.

#4 Sauroposeidon — Approx. 50 Tons

Ecological reconstruction of Sauroposeidon Sauroposeidon proteles is estimated at approximately 50 tons and 34 m in length.
It is notable for its exceptionally long cervical vertebrae reaching up to 1.4 m, potentially allowing its head to reach heights of up to 17 m above the ground when raised. This made it an overwhelming dinosaur not only in length, but also in vertical height.

#5 Turiasaurus — Approx. 48 Tons

Ecological reconstruction of Turiasaurus Turiasaurus riodevensis is estimated at approximately 48 tons and 30 m in length, standing as one of Europe's largest known dinosaurs. While titanosaurs from South America often come to mind when thinking of super-giant dinosaurs, Turiasaurus demonstrates that gigantic body sizes could evolve independently across different lineages.

#6 Paralititan — Approx. 40 Tons

Size and skeletal reconstruction of Paralititan Paralititan stromeri is estimated at approximately 40 tons and nearly 30 m in length, making it one of Africa's largest titanosaurs.
It is known to have inhabited the Cretaceous mangrove environments of Egypt. However, because its fossils are fragmentary, overall body proportions and mass estimates involve considerable speculation.

#7 Futalognkosaurus — Approx. 38 Tons

Reconstruction of Futalognkosaurus Futalognkosaurus dukei is estimated at approximately 38 tons and 26 m in length.
With relatively complete skeletons known across multiple individuals, this dinosaur serves as an important benchmark for understanding the build of giant titanosaurs with wide, heavily built torsos.

#8 Alamosaurus — Approx. 33 Tons

Reconstruction of Alamosaurus Alamosaurus sanjuanensis is estimated at approximately 33 tons and 30 m in length.
It was one of the last giant sauropods living in North America during the Late Cretaceous period, with some large specimens potentially reaching lengths of around 30 m.

#9 Dreadnoughtus — Approx. 30 Tons

Skeletal reconstruction of Dreadnoughtus based on publication Dreadnoughtus schrani is set at approximately 30 tons and 26 m in length in this comparison.
The large specimen discovered is known to have not been fully grown at the time of death.
Although an initial estimate of around 59 tons was proposed, it sparked debate; ScaleCheck uses approximately 30 tons as a representative value reflecting subsequent volumetric studies.

#10 Notocolossus — Approx. 30 Tons

Skeletal reconstruction of Notocolossus Notocolossus gonzalezparejasi is a titanosaurean sauropod from Argentina estimated at approximately 30 tons and 25 m in length.
Although a massive humerus and peculiarly short, broad foot bones were discovered, the overall skeleton remains incomplete.
Consequently, its exact body shape and size may also be updated as new fossils are uncovered in the future.

Why Do Rankings of the Largest Dinosaurs Change?

Dinosaur body weights and lengths are mostly estimates derived from fossil reconstructions rather than direct measurements. Depending on the completeness of surviving fossils and the reconstruction methods used, size estimates for the same dinosaur can vary across different studies.

In particular, dinosaurs with highly fragmentary fossils such as Argentinosaurus, Puertasaurus, and Paralititan can yield vastly different estimates depending on the research methodology. Conversely, dinosaurs like Patagotitan, for which numerous fossil bones across multiple individuals have been secured, have relatively abundant evidence supporting their reconstruction.

Thus, the title of "the largest dinosaur in history" is less of a fixed, single figure and more of a living record that updates whenever new fossils and scientific studies emerge.

Giants That Walked the Earth

Giant dinosaur A body mass of tens of tons and lengths exceeding 30 meters are hard to fathom from numbers alone. However, standing a dinosaur next to familiar objects like humans, cars, or buildings at the exact same scale makes their size feel entirely different.

In ScaleCheck's 3D comparison, 10 species from Argentinosaurus to Notocolossus are placed in the same space, allowing you to directly check the differences in length and height of each.
Comparing them in real-world scale also makes it far clearer that the heaviest dinosaur and the longest dinosaur are indeed distinct.