The heaviest dinosaur ever weighed almost as much as ten T-Rexes — and walked on four legs to do it.
How to Play: Guess if the dinosaur on the right was HEAVIER or LIGHTER than the one on the left.
Name A
Name B
Top 10 Heaviest Dinosaurs
Sauropods — the long-necked herbivores — dominate the dinosaur weight rankings. They evolved a unique skeletal architecture (hollow vertebrae, columnar legs, four-chambered hearts) that let them grow to sizes no other land animal would ever match.
Predator dinosaurs, even the famous T-Rex, never came close to sauropod mass. Tyrannosaurus rex weighed about as much as one African elephant; Argentinosaurus weighed as much as 14.
| # | Name | Estimated Weight (tonnes) | Unit |
|---|---|---|---|
| 1 | Argentinosaurus | 80 | tonnes |
| 2 | Patagotitan | 70 | tonnes |
| 3 | Dreadnoughtus | 65 | tonnes |
| 4 | Puertasaurus | 60 | tonnes |
| 5 | Futalognkosaurus | 50 | tonnes |
| 6 | Brachiosaurus | 40 | tonnes |
| 7 | Mamenchisaurus | 25 | tonnes |
| 8 | Apatosaurus | 20 | tonnes |
| 9 | Camarasaurus | 18 | tonnes |
| 10 | Brontosaurus | 17 | tonnes |
How Dinosaur Weights Are Estimated
Dinosaur weights are reconstructed from fossilized bones using two main methods. The volumetric method builds a 3D digital model of the animal from skeleton scans and estimates flesh density. The scaling method extrapolates from limb-bone circumference, which correlates with body mass in modern animals.
Both methods produce uncertainty bands. Argentinosaurus is estimated at 65–95 tonnes depending on which leg-bone scaling formula is used. Patagotitan likewise has wide error bars — 55–75 tonnes is a reasonable range. Headline figures used in popular media tend to pick the upper end.
Tyrannosaurus rex (‘king tyrant lizard’), found across western North America, is the largest carnivorous dinosaur known from substantial fossil remains. It weighed about 8 tonnes — roughly 1/10th the heaviest sauropod. Spinosaurus may have been longer than T-Rex but was lighter, with a sail-like back fin and possibly semi-aquatic lifestyle.
Almost all of the heaviest sauropods come from one place: Patagonia, in Argentina. The geology there preserves Late Cretaceous fossils unusually well, and ongoing field work continues to add new species — Argentinosaurus, Patagotitan, Dreadnoughtus, and Puertasaurus were all named between 1993 and 2017.
Frequently Asked Questions
What was the heaviest dinosaur ever?
Argentinosaurus, at an estimated 80 tonnes (with a wide range of 65–95 tonnes depending on method). Patagotitan and Dreadnoughtus are close runners-up.
How heavy was T-Rex?
Tyrannosaurus rex weighed about 8 tonnes — roughly the same as a single African elephant. Larger predators existed (Spinosaurus, Giganotosaurus) but T-Rex remains the most-studied apex predator.
Are these weights certain?
No. Dinosaur masses are estimates based on bone scaling and volume reconstruction. Different methods can produce values that differ by 30–50%. Headline figures lean toward the upper bounds.
Was T-Rex bigger than Spinosaurus?
Spinosaurus was longer (15–18 m vs T-Rex’s 12–13 m) but lighter, with a more slender body. T-Rex was more massively built.
Note: Weights are best published mid-range estimates in metric tonnes. Paleontology updates regularly; some figures may shift as new specimens are described.
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