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Yamatosaurus

Say it: yah-MAH-toh-SORE-us

Name means: “Yamato reptile”1

Ate: PlantsDuck-billsLate Cretaceous

Yamatosaurus was a duck-billed dinosaur that lived in Japan near the end of the age of dinosaurs. It had a special jaw with only one tooth at a time in each spot, which is different from most other duck-billed dinosaurs. This plant-eater probably lived in coastal areas.2 1

Lived

72 to 66 million years ago4

Late Cretaceous

Fossils found in

Awaji Island, Hyogo Prefecture, Japan2 1

Food

Plants3

Length

10 m3

estimate from PBDB adult length range

Height

1 m3

estimate from PBDB adult height range

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

as long as 2 cars parked in a rowas long as 56 bananas end to endup to the handle of a door

How big was Yamatosaurus compared to YOU?

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cool stuff

Fun facts

Yamatosaurus had only one tooth in each tooth socket at a time, which is very unusual for a duck-billed dinosaur.2

It lived about 72 to 66 million years ago during the Maastrichtian stage of the Late Cretaceous.3

The fossils were found in marine rocks, meaning the dinosaur's body was washed into the sea after it died.2

Yamatosaurus is one of the oldest known hadrosaurids, or duck-billed dinosaurs, from Japan.2

Its shoulder bone, the coracoid, lacks a bump called the biceps tubercle, which is a primitive feature.2

The name Yamatosaurus comes from Yamato, an ancient name for Japan.1

AI-made picture of Yamatosaurus — An AI-made picture of how Yamatosaurus might have looked, made by a computer from what scientists know. It is a guess: the real animal may have looked different, and nobody knows its true colours.

you asked

Most asked questions about Yamatosaurus

?How big was Yamatosaurus?

Scientists do not know its exact size because only a partial skeleton has been found, including parts of the jaw, neck bones, and shoulder bone.1 2

?What did Yamatosaurus eat?

It was a plant-eater, like other duck-billed dinosaurs. Its teeth were adapted for chewing plants.1

?When did Yamatosaurus live?

It lived about 71.94 to 71.69 million years ago, during the early Maastrichtian stage of the Late Cretaceous.1 2

?Where was Yamatosaurus found?

Its fossils were discovered on Awaji Island in Japan, in rocks that were once at the bottom of the sea.1 2

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For dino experts

Scientific name: Yamatosaurus
Named by: Kobayashi et al. 20214
Group: Duck-bills
Family / clade: Hadrosauridae4
Classification: Ornithischia > Ornithopoda > Iguanodontia > Hadrosauridae4
Age of the rocks: 72 to 66 million years (Maastrichtian)4
Rock formations: Kita-ama4
Countries: Japan4
Fossil records: 1 in the Paleobiology Database4
Discovery: An amateur fossil collector named Shingo Kishimoto discovered the partial skeleton in May 2004 on Awaji Island, Japan. Scientists Yoshitsugu Kobayashi and colleagues named it Yamatosaurus izanagii in 2021.1 2
Still debated: Scientists are not sure exactly how Yamatosaurus is related to other duck-billed dinosaurs, but they think it is a very early member of the group.2

Where the facts come from

Yamatosaurus (en.wikipedia.org)
nature.com (nature.com)
PBDB Taxon (paleobiodb.org)
Yamatosaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

Every fact on this page has a number that points to its source. If we got something wrong, sorry, we are dino fans, not a science journal. Tell us at [email protected] and we will fix it.

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