The longest animals that ever lived
Twelve of the longest animals known, living and extinct, ranked by their length from nose to tail in metres, using the latest figure each museum or journal gives, the newest from 2025.
Length in metres, nose to tail
Metres long, nose to tail. Extinct animals are estimates from fossils; living animals are the biggest measured or reported.
| Rank | Animal | Length (metres) |
|---|---|---|
| 1 | PatagotitanDinosaur, extinct, about 101 million years ago, Argentina | 37.5 |
| 2= | ArgentinosaurusDinosaur, extinct, about 90 million years ago, Argentina | 35 |
| 2= | SupersaurusDinosaur, extinct, USA; known only from some bones | 35 |
| 4 | Blue whaleLiving; some reach 100 feet; the longest animal on this list that is still alive | 30.5 |
| 5 | DiplodocusDinosaur, extinct, 152 to 145 million years ago, USA | 26 |
| 6 | IchthyotitanSea reptile (ichthyosaur), extinct, end of the Triassic, England; known from two jawbones | 25 |
| 7 | MegalodonShark, extinct; the 2025 study's estimate of the size it possibly reached (older studies said 15 to 20 metres) | 24.3 |
| 8 | Perucetus colossusEarly whale, extinct, about 39 million years ago, Peru; a contender for heaviest animal of all time | 20 |
| 9 | Whale sharkLiving; the largest fish; one of the biggest ever reported | 18.8 |
| 10 | SpinosaurusDinosaur, extinct, 99 to 94 million years ago, Egypt and Morocco | 14 |
| 11 | TitanoboaSnake, extinct, Colombia; probably grew 45 feet | 13.7 |
| 12 | Tyrannosaurus rexDinosaur, extinct, 68 to 66 million years ago, USA and Canada | 12 |
Measured from nose to tail, the longest animal known is Patagotitan, a plant-eating dinosaur from Argentina, at 37.5 metres. Two more long-necked dinosaurs, Argentinosaurus and Supersaurus, come next at about 35 metres each.
The blue whale is the longest animal on the list that is still alive. Some reach 100 feet, about 30.5 metres, longer than Diplodocus at 26 metres and longer than the biggest sea reptile and the biggest shark known from fossils.
What the figures include
This ranking is by length, not weight. Long-necked dinosaurs were longer than any whale but much lighter: Patagotitan weighed about 57,000 kg, while a blue whale weighs some 150 tons. The blue whale, often called the largest animal that has ever lived, is fourth here by length. Perucetus colossus, an early whale from Peru, was shorter than a blue whale but is a contender for the heaviest animal of all time.
For extinct animals the figure is an estimate worked out from fossil bones, often only a few of them, and it can change when more bones are found. We use the single figure the museum or study gives as its estimate. For megalodon that is the 2025 study's 24.3 metres, the size it says the shark possibly reached; older studies put it at 15 to 20 metres. For Ichthyotitan it is the study's estimate of about 25 metres worked out from the more complete of its two jawbones. Titanoboa's 45 feet and the blue whale's 100 feet are turned into metres.
For living animals the figure is the biggest one measured or reported, not a typical adult. Most whale sharks measured are around 12 metres, and the 18.8-metre female is one of the biggest ever reported.
Article Sources
- Natural History Museum, London, Dino Directory: Patagotitan
- Natural History Museum, London, Dino Directory: Argentinosaurus
- Natural History Museum, London, Dino Directory: Supersaurus
- Smithsonian, The Object at Hand (the National Museum of Natural History's blue whale model)
- Natural History Museum, London, Dino Directory: Diplodocus
- Lomax et al. 2024, The last giants: New evidence for giant Late Triassic (Rhaetian) ichthyosaurs from the UK, PLOS ONE
- Shimada et al. 2025, Reassessment of the possible size, form, weight, cruising speed, and growth parameters of the extinct megatooth shark, Otodus megalodon, Palaeontologia Electronica
- State Museum of Natural History Stuttgart, New early whale is possibly the heaviest animal of all time
- Natural History Museum, London, Whale sharks: Meet the world's biggest shark
- Natural History Museum, London, Dino Directory: Spinosaurus
- Florida Museum of Natural History, At 45 feet long, Titanoboa snake ruled the Amazon
- Natural History Museum, London, Dino Directory: Tyrannosaurus
