Giants of deep time
20 of the Largest Dinosaurs: Length Comparison
Compare Argentinosaurus, Diplodocus, Dreadnoughtus and other giants using published length estimates, with a source and a full atlas record for every dinosaur.
Explore the animals 20 ↘
Which dinosaur was biggest: longest, heaviest or tallest?
This guide compares sourced reference lengths. Long necks and tails add length without necessarily making an animal heavier. Shoulder height, hip height and a raised head are also different measurements. Giant sauropods such as Argentinosaurus are central to size comparisons, but this length table cannot establish a mass ranking.
Compare completeness
An isolated bone, a partial skeleton and a largely complete skeleton require different assumptions about missing parts. Two estimates of 30 metres do not necessarily carry the same confidence.
Why Dreadnoughtus mass estimates differ ↗Compare with T. rex
Choose the same measurement and comparable adults or specimens. A longer dinosaur need not outweigh a large T. rex, and the biggest specimen is not the average for a genus.
T. rex height, length and weight ↗How this list was selected
Selected large dinosaurs already in this atlas, ordered by the Natural History Museum’s genus-level reference lengths, checked on 3 September 2026. These are approximate reconstructions, not maximum specimen measurements or a complete world ranking. A longer animal need not be heavier. Equal values share the same size estimate; list positions do not resolve ties. The linked species is the atlas representative of that genus.
In this guide 20
Explore the animals
20 atlas recordsAbout 96–92 million years ago
Argentinosaurus
Argentinosaurus huinculensis
Estimated body length · genus reference≈ 35 mA handful of colossal vertebrae and limb bones indicate one of the largest land animals known.
South America · Present-day Argentina
Natural History Museum, London — argentinosaurus ↗
About 154–152 million years ago
Diplodocus
Diplodocus carnegii
Estimated body length · genus reference≈ 26 mA whip-like tail balanced an extremely long neck on this lightly built giant.
Western North America
Natural History Museum, London — diplodocus ↗
About 77 million years ago
Dreadnoughtus
Dreadnoughtus schrani
Estimated body length · genus reference≈ 26 mA relatively complete skeleton makes this giant titanosaur unusually measurable.
Floodplain woodland · Patagonia, Argentina
Natural History Museum, London — dreadnoughtus ↗
About 154–150 million years ago
Brachiosaurus
Brachiosaurus altithorax
Estimated body length · genus reference≈ 22 mLong forelimbs lifted its shoulders and neck toward the Jurassic canopy.
Western North America
Natural History Museum, London — brachiosaurus ↗
About 160–155 million years ago
Mamenchisaurus
Mamenchisaurus hochuanensis
Estimated body length · genus reference≈ 22 mNineteen elongated neck vertebrae placed nearly half the body's length in the neck, lightened internally by air spaces.
Lake and river woodland · Southwestern China
Natural History Museum, London — mamenchisaurus ↗
About 170–164 million years ago
Jobaria
Jobaria tiguidensis
Estimated body length · genus reference≈ 21 mA relatively short neck, strong limbs and primitive vertebrae belonged to a large non-neosauropod herbivore.
River floodplain · Niger
Natural History Museum, London — jobaria ↗
About 100–93.5 million years ago
Spinosaurus
Spinosaurus aegyptiacus
Estimated body length · genus reference≈ 14 mA sail-backed predator with dense bones and a paddle-like tail, adapted to life around water.
North African rivers and deltas
Natural History Museum, London — spinosaurus ↗
About 68–66 million years ago
Edmontosaurus
Edmontosaurus annectens
Estimated body length · genus reference≈ 13 mA broad duck bill and dense dental batteries processed huge amounts of vegetation.
Western North America
Natural History Museum, London — edmontosaurus ↗
About 99.6–97 million years ago
Giganotosaurus
Giganotosaurus carolinii
Estimated body length · genus reference≈ 13 mA giant narrow-skulled theropod shared its world with immense sauropods.
South America · Present-day Argentina
Natural History Museum, London — giganotosaurus ↗
About 113–110 million years ago
Acrocanthosaurus
Acrocanthosaurus atokensis
Estimated body length · genus reference≈ 12 mTall neural spines along the neck and back supported a muscular ridge rather than a paper-thin sail.
River plains and open woodland · North America
Natural History Museum, London — acrocanthosaurus ↗
About 129–122 million years ago
Amargasaurus
Amargasaurus cazaui
Estimated body length · genus reference≈ 12 mTwo rows of elongated neck spines made its profile unique, though their soft-tissue covering remains debated.
South America · Present-day Argentina
Natural History Museum, London — amargasaurus ↗
About 72–66 million years ago
Saltasaurus
Saltasaurus loricatus
Estimated body length · genus reference≈ 12 mSmall bony plates embedded in the skin showed that some titanosaurs carried armor.
Semi-arid floodplains · Argentina
Natural History Museum, London — saltasaurus ↗
About 68–66 million years ago
Tyrannosaurus
Tyrannosaurus rex
Estimated body length · genus reference≈ 12 mA deep skull, bone-crushing bite and keen senses made it one of the last giant theropods.
Western North America
Natural History Museum, London — tyrannosaurus ↗
About 130–125 million years ago
Baryonyx
Baryonyx walkeri
Estimated body length · genus reference≈ 10 mA crocodile-like snout and huge thumb claw equipped this theropod to catch fish and other prey.
River and lake country of Western Europe · Present-day Britain
Natural History Museum, London — baryonyx ↗
About 77–75 million years ago
Corythosaurus
Corythosaurus casuarius
Estimated body length · genus reference≈ 10 mA helmet-shaped hollow crest contained looping nasal passages that could shape resonant calls.
Coastal plains · Alberta, Canada
Natural History Museum, London — corythosaurus ↗
About 71–69 million years ago
Deinocheirus
Deinocheirus mirificus
Estimated body length · genus reference≈ 10 mHuge arms, a broad bill, a tall back and wide feet formed one of the strangest dinosaur silhouettes.
Mongolian Plateau
Natural History Museum, London — deinocheirus ↗
About 126–122 million years ago
Iguanodon
Iguanodon bernissartensis
Estimated body length · genus reference≈ 10 mA conical thumb spike and batteries of chewing teeth equipped this adaptable herbivore.
Western Europe
Natural History Museum, London — iguanodon ↗
About 70–66 million years ago
Therizinosaurus
Therizinosaurus cheloniformis
Estimated body length · genus reference≈ 10 mMeter-long hand claws belonged to a tall, feathered, pot-bellied herbivore.
Mongolian Plateau
Natural History Museum, London — therizinosaurus ↗
About 153–148 million years ago
Torvosaurus
Torvosaurus tanneri
Estimated body length · genus reference≈ 10 mA huge skull and unusually powerful three-fingered arms marked one of the largest megalosaurids.
River plains and open woodland · North America
Natural History Museum, London — torvosaurus ↗
About 155–145 million years ago
Allosaurus
Allosaurus fragilis
Estimated body length · genus reference≈ 9.7 mA lightweight skull and serrated teeth equipped this large predator for repeated slashing bites.
Western North America
Natural History Museum, London — allosaurus ↗
