Koshisaurus

Say it: ko-shee-SORE-us

Name means: “Koshi lizard, after the old name for the region where it was found”1

Ate: PlantsBeaked plant-eatersEarly Cretaceous

Koshisaurus was a plant-eating dinosaur that lived in what is now Japan. It walked on two legs and had a beak for snipping leaves. This dinosaur was one of the earliest relatives of the duck-billed hadrosaurs.2 1

Lived

121 to 113 million years ago5

Early Cretaceous

Fossils found in

Fukui Prefecture, Japan2 1

Food

Plants2

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

cool stuff

Fun facts

Koshisaurus lived about 121 to 113 million years ago during the Early Cretaceous.2

It was a basal hadrosauroid, meaning it was an early relative of the duck-billed dinosaurs.1

Koshisaurus had an antorbital fossa, a hole in front of its eye socket on the skull, which is a primitive feature.1

Its teeth had at least three subsidiary ridges on the outer side, helping it grind plants.1

Koshisaurus shared its home with other dinosaurs like Fukuisaurus, Fukuiraptor, and Fukuititan.1

AI-made picture of Koshisaurus — An AI-made picture of how Koshisaurus 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 Koshisaurus

?How big was Koshisaurus?

Scientists have not found enough bones to know its full size, but it was likely smaller than later duck-billed dinosaurs. Only a partial skeleton is known.1 3

?What did Koshisaurus eat?

It ate plants, using its beak to snip leaves and its ridged teeth to grind them up.4 3

?When did Koshisaurus live?

It lived during the Early Cretaceous, about 125 to 115 million years ago.3 5

?Where was Koshisaurus found?

Its fossils were found in Fukui Prefecture, Japan, in the Kitadani Formation.4 3

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For dino experts

Scientific name: Koshisaurus
Named by: Shibata and Azuma 20155
Group: Beaked plant-eaters
Family / clade: Hadrosauroidea5
Classification: Ornithischia > Ornithopoda > Iguanodontia5
Age of the rocks: 121 to 113 million years (Aptian)5
Rock formations: Kitadani5
Countries: Japan5
Fossil records: 1 in the Paleobiology Database5
Discovery: Koshisaurus was named by Masateru Shibata and Yoichi Azuma in 2015 based on fossils from the Kitadani Formation in Fukui, Japan.2 1
Still debated: Scientists are not sure exactly how big Koshisaurus grew, because only partial fossils have been found.2

Where the facts come from

New basal hadrosauroid (Dinosauria: Ornithopoda) from the Lower Cretaceous Kitadani Formation, Fukui, central Japan | Zootaxa (biotaxa.org)
PBDB Taxon (paleobiodb.org)
Koshisaurus (en.wikipedia.org)
勝山市の発掘現場から発見された恐竜に新しい学名が付けられました｜恐竜博物館の調査研究｜FPDM: 福井県立恐竜博物館 (dinosaur.pref.fukui.jp)
Koshisaurus in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

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