Its neck alone was longer than a school bus! Meet Mamenchisaurus, the neck champion of all time, and see how its neck measures up to other long-necks and to a giraffe.
Quick Answer
The dinosaur with the longest neck was Mamenchisaurus sinocanadorum, a plant-eater from China. Its neck was about 15 meters (49 feet) long. That is longer than a school bus and about six times as long as a giraffe's neck. It is the longest neck of any animal ever known.
Say it: mah-MUN-chee-SORE-us sy-no-can-a-DOR-um
Mamenchisaurus was a sauropod, one of the giant long-necked dinosaurs that walked on four legs and ate plants. Its name means “Mamenxi lizard,” after the place in China where the first Mamenchisaurus was found. The second part, sinocanadorum, honors the team of Chinese and Canadian scientists who dug it up.
Scientists have found only part of it: some neck bones, a neck rib, a lower jaw and a few skull bones. In 2023 they compared those bones with a close cousin that has a complete neck, Xinjiangtitan, and worked out that the neck was about 15.1 meters long.
Neck length
About 15 meters (49½ feet)
Neck bones
Probably 18 (a giraffe has 7)
When it lived
About 162 million years ago (Jurassic)
Where
Xinjiang, northwest China
Found
1987, named in 1993
Ate
Plants: leaves, ferns and conifer needles
Fifteen meters is hard to picture, so here are some ways to see it:
Longer than a school bus
A big school bus is about 12 m (40 ft). The neck was 3 m longer.
6 giraffe necks
Line up six giraffe necks end to end to match it.
15 preschoolers
About 15 four-year-olds lying head to toe.
As tall as 5 floors
Stood straight up, it would reach the roof of a 5-story building.
Here are the longest necks scientists know about, measured from the head to the shoulders, with a giraffe at the bottom for scale. Lots of these are estimates, because long necks are fragile and rarely found whole.
Mamenchisaurus sinocanadorumrecord holder (estimate)
Supersaurusestimate from a few bones
Xinjiangtitanlongest neck found in one piece
Sauroposeidonestimate
Mamenchisaurus hochuanensiscomplete neck
Giraffatitan (Brachiosaurus’s cousin)complete neck
Barosaurusestimate
Diplodocus
Apatosaurus
Giraffe (longest neck alive today)
Say it: SOO-per-SORE-us
📏 Neck: Maybe about 15 m (49 ft)
🗺️ 150 million years ago, Colorado, USA
⭐ A super-long cousin of Diplodocus and one of the longest dinosaurs from nose to tail. Its neck could rival Mamenchisaurus, but scientists have only a few of its neck bones, so the estimate is less certain.
Say it: shin-jee-AHNG-tie-tan
📏 Neck: At least 13.4 m (44 ft)
🗺️ 160 million years ago, China
⭐ The longest dinosaur neck ever found all in one piece, with all 18 neck bones. Scientists used it as a guide to work out how long Mamenchisaurus sinocanadorum’s neck was.
Say it: SORE-oh-po-SY-don
📏 Neck: About 11.5 m (38 ft)
🗺️ 110 million years ago, Oklahoma and Texas, USA
⭐ Named after Poseidon, the Greek god of earthquakes. Its neck bones were so big that, when they were first dug up, people thought they were fossil tree trunks!
Say it: mah-MUN-chee-SORE-us
📏 Neck: About 9.5 m (31 ft)
🗺️ 155 million years ago, China
⭐ The record holder’s smaller cousin. Its whole neck was found, so we know exactly how long it was. Its neck made up almost half of its whole body.
Say it: BARE-oh-SORE-us
📏 Neck: About 8.5 m (28 ft)
🗺️ 150 million years ago, USA
⭐ A famous skeleton in New York’s American Museum of Natural History rears up on its back legs, lifting its long neck high to protect its baby.
Meet more of these gentle giants, like Brachiosaurus, Diplodocus and Brontosaurus, on our long-neck dinosaurs page.
Nobody knows for sure, but scientists have some good ideas:
Eating without walking
A giant body takes lots of energy to move. With a long neck, it could stand still and sweep its head around, munching a huge circle of plants, like a living vacuum cleaner.
Staying cool
A big animal gets hot. A long neck has lots of skin for letting heat out, a bit like an elephant's big floppy ears.
Showing off
A giant neck might have helped impress mates or win pushing contests, the way male giraffes swing their necks today. Scientists call this idea a guess for now.
Sea reptile
Elasmosaurs
These swimming reptiles, like Albertonectes, had necks about 7 meters (23 feet) long with more than 70 neck bones, the most of any animal. But they were plesiosaurs, not dinosaurs. Learn why on our water dinosaurs page.
Fun opposite
The long-neck with a short neck
Brachytrachelopan, from Argentina, was a sauropod with a neck only about 1 meter (3 feet) long. It probably ate low plants, like a big dinosaur lawnmower.
👪 For parents and teachers
Make the neck real: take a tape measure outside and mark 15 meters (49 feet) with chalk, then mark 2.4 meters (8 feet) for a giraffe beside it. Kids can lie down along the line and count how many of them fit. It is also a nice way to talk about how scientists make careful estimates from only a few bones.
Mamenchisaurus sinocanadorum, a plant-eating sauropod from China, had the longest neck of any known dinosaur. A 2023 study estimated its neck at about 15.1 meters (49½ feet), and Guinness World Records lists it as the record holder.
Mamenchisaurus sinocanadorum’s neck was about 15 meters (49½ feet) long. That is longer than a school bus and about six times as long as a giraffe’s neck. Its smaller cousin, Mamenchisaurus hochuanensis, had a neck about 9.5 meters (31 feet) long.
No. Mamenchisaurus had a giant neck but a smaller body and tail than the true heavyweights. The heaviest dinosaurs were titanosaurs like Argentinosaurus and Patagotitan, which weighed as much as 10 elephants.
No, but it could reach the highest. Brachiosaurus and its cousin Giraffatitan had necks about 8.5 to 9 meters (28 to 30 feet) long, much shorter than Mamenchisaurus. They held their necks more upright, though, so they could nibble leaves about as high as a four-story building.
Scientists think Mamenchisaurus sinocanadorum had 18 neck bones, because its close relatives with complete necks have 18. A giraffe has only 7, the same number as you!
The giraffe. A big male giraffe’s neck can be about 2.4 meters (8 feet) long. That is long for an animal today, but Mamenchisaurus’s neck was about six times longer.
All illustrations on this page are original Puffsaurus artwork. Sources: Moore et al. (2023), Journal of Systematic Palaeontology; Guinness World Records; Taylor & Wedel (2013), PeerJ.
Stretch your neck and sing along! 🦕
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