The ten longest dinosaurs that ever lived, ranked by estimated maximum body length — from the colossal Argentinosaurus down to Diplodocus.
Quick answer: 1. Mamenchisaurus sinocanadorum, 2. Supersaurus vivianae, 3. Argentinosaurus, 4. Patagotitan mayorum, 5. Diplodocus hallorum (formerly Seismosaurus), 6. Sauroposeidon proteles, 7. Futalognkosaurus dukei, 8. Barosaurus lentus, 9. Alamosaurus sanjuanensis, 10. Diplodocus carnegii.
The largest dinosaurs were the sauropods — long-necked, four-legged herbivores that stretched longer than a tennis court and weighed as much as a dozen elephants. Because no complete skeleton has ever been found for many of these giants, their lengths are estimates based on the fossils that have been unearthed: a thigh bone here, a few vertebrae there, scaled against more complete relatives. This list ranks the ten longest dinosaurs by their estimated maximum body length, from nose tip to tail tip. The numbers come from peer-reviewed palaeontology papers and museum exhibits, not pop culture. Most of these species were discovered in the last 30 years, so the order may shift as new fossils are found — but for now, here's how the all-time heavyweight bracket stacks up.
This Chinese sauropod from the Late Jurassic may have reached 35 m thanks to an extraordinary 15-m-long neck — the longest neck-to-body ratio of any known animal. The 35 m figure comes from a 2023 re-examination of the fossil.
Supersaurus is one of the longest known sauropods from North America, estimated at 33–34 m. Discovered in Colorado in 1972, it was originally thought to be even larger; revised estimates place it among the very longest.
At an estimated 30–35 m, Argentinosaurus is widely considered the longest — and heaviest — dinosaur ever discovered. Known only from a handful of massive vertebrae and a femur, this Late Cretaceous titanosaur from Argentina was named in 1993.
Discovered in Patagonia and described in 2014, Patagotitan is one of the most complete giant sauropods ever found. Its holotype skeleton suggests a length of about 31 m, though headlines have sometimes claimed longer.
Known from a partial skeleton found in New Mexico, this diplodocid was long thought to be the longest dinosaur ever. Current estimates place its length at 30–32 m, with a whip-like tail that made up more than half its body.
Standing an estimated 17 m tall — the tallest dinosaur known — Sauroposeidon reached about 30 m in length. Its 11-m neck vertebrae were so enormous they were initially mistaken for tree trunks.
This Patagonian titanosaur is known from a relatively complete skeleton, giving palaeontologists confidence in its length estimate of 26–30 m. Its name means 'giant chief lizard' in the Mapuche language.
Closely related to Diplodocus, Barosaurus had an exceptionally long neck and a relatively short tail. The most complete specimen, mounted at the American Museum of Natural History, measures about 27 m.
One of the last surviving sauropods, Alamosaurus flourished in Late Cretaceous North America. Fragmentary remains suggest lengths of 25–26 m, making it the largest dinosaur known from North America.
The classic 'Diplodocus' — the species whose mounted casts have been gifted to museums around the world. At about 25 m, it rounds out the top ten as one of the best-known of all sauropods.
| # | Name | Estimated length (m) | Estimated mass (tonnes) | Period | Location found | Year described |
|---|---|---|---|---|---|---|
| 1 | Mamenchisaurus sinocanadorum | 35 | 60–75 | Late Jurassic (161–145 mya) | China | 1993 |
| 2 | Supersaurus vivianae | 33–34 | 35–40 | Late Jurassic (153 mya) | USA (Colorado) | 1985 |
| 3 | Argentinosaurus | 30–35 | 65–80 | Late Cretaceous (94–86 mya) | Argentina | 1993 |
| 4 | Patagotitan mayorum | 31 | 50–70 | Late Cretaceous (101 mya) | Argentina | 2014 |
| 5 | Diplodocus hallorum (formerly Seismosaurus) | 30–32 | 30–40 | Late Jurassic (155–145 mya) | USA (New Mexico) | 1991 |
| 6 | Sauroposeidon proteles | 30 | 40–60 | Early Cretaceous (113 mya) | USA (Oklahoma, Texas) | 2000 |
| 7 | Futalognkosaurus dukei | 26–30 | 30–50 | Late Cretaceous (87 mya) | Argentina | 2007 |
| 8 | Barosaurus lentus | 27 | 20–30 | Late Jurassic (155–145 mya) | USA (Utah, South Dakota) | 1890 |
| 9 | Alamosaurus sanjuanensis | 25–26 | 30–35 | Late Cretaceous (70–66 mya) | USA (Texas, Utah, New Mexico) | 1922 |
| 10 | Diplodocus carnegii | 25 | 15–25 | Late Jurassic (155–145 mya) | USA (Wyoming, Colorado, Utah) | 1878 |
Dinosaurs are ranked by estimated maximum body length in metres, from nose tip to tail tip (rank 1 = longest). Only sauropod dinosaurs with published, peer-reviewed length estimates are included; fragmentary species whose lengths rely on heavy extrapolation from a handful of bones are excluded unless the estimate is widely cited in the literature. Length estimates come from the original describing paper or a subsequent major review, cited via the sources below. The primary reference sources are the Wikipedia article 'Largest dinosaurs' (which aggregates peer-reviewed estimates) and the individual Wikipedia pages for each genus. Where estimates span a range, the midpoint or maximum accepted value is used.
The current title holder is likely Argentinosaurus, estimated at 30–35 m in length, though Mamenchisaurus sinocanadorum may have reached 35 m. Because no complete skeleton exists for either, the exact record depends on which reconstruction you use.
Most giant sauropods are known only from partial skeletons — a few vertebrae, a femur, some ribs. Length estimates require palaeontologists to scale those fragments against more complete relatives, and different scaling assumptions produce different numbers.
No. T. rex reached about 12–13 m — less than half the length of the longest sauropods. Tyrannosaurs were heavy predators, but the sauropods were in a completely different size league.
Not quite. Blue whales reach about 30 m in length but can weigh over 170 tonnes — far more than any known dinosaur. The longest dinosaurs matched or exceeded the blue whale in length, but no dinosaur approached its bulk.