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Atopodentatus

Say it: ay-TOP-oh-den-TAY-tus

Name means: “unusual tooth”1

Ate: PlantsOther sea reptilesMiddle TriassicNot technically a dinosaur

Atopodentatus was a weird marine reptile that lived in the sea about 245 million years ago. It had a hammer-shaped head and used its special teeth to scrape algae off rocks, like a underwater lawnmower.2

Fun fact: this sea reptile swam while dinosaurs walked on land. Everyone calls them dinos, but they were a different branch of reptiles.

Lived

244 to 243 million years ago3

Middle Triassic

Fossils found in

Luoping County, Yunnan Province, China1

Food

Plants2

Length

2.75 m1

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

as long as 1.5 bicycles in a rowas long as 15 bananas end to end

How big was Atopodentatus compared to YOU?

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cool stuff

Fun facts

Atopodentatus is the oldest known plant-eating marine reptile. It lived about 6 million years after the great Permian extinction.2

Its head was shaped like a hammer, similar to a hammerhead shark. But Atopodentatus used its hammerhead for grazing on algae, not for sensing prey.2

The front of its jaws had chisel-shaped teeth for scraping algae. The back of its jaws had a mesh of needle-shaped teeth that acted like a strainer.2

Atopodentatus was about 2.75 meters (9 feet) long, about as long as a small car.1

Scientists first thought Atopodentatus had a downturned snout and was a filter feeder. But new skulls in 2016 showed it actually had a hammerhead.1

Atopodentatus lived in shallow seas near the coast, where algae grew on rocks. It probably could walk on land or mudflats.1

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

?What did Atopodentatus eat?

Atopodentatus ate algae, scraping it off rocks with its chisel-shaped front teeth and filtering the bits with needle-like teeth in the back of its mouth.1 2

?How big was Atopodentatus?

Atopodentatus was about 2.75 meters (9 feet) long, roughly the size of a large dog.1

?Was Atopodentatus a dinosaur?

No, Atopodentatus was a marine reptile called a sauropterygian, not a dinosaur. It lived in the sea, not on land.1

?Why did Atopodentatus have a hammer-shaped head?

The hammer-shaped head helped Atopodentatus scrape algae off the seabed. Its wide jaws had chisel-like teeth for scraping, and the shape was unique among marine reptiles.2 1

?When did Atopodentatus live?

Atopodentatus lived about 247 to 240 million years ago, during the Middle Triassic period, about 6 million years after the Permian extinction.1

?Could Atopodentatus walk on land?

Scientists think Atopodentatus was semi-aquatic and could probably walk on land or mudflats, based on its body structure.1

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Myth buster

Myth: Atopodentatus was a filter feeder that sucked up small animals from the seafloor.

Truth: New fossils show it had a hammer-shaped head and used its front teeth to scrape algae, then filtered the plant bits through its back teeth. It was a plant eater.2

For dino experts

Scientific name: Atopodentatus
Named by: Cheng et al. 20143
Group: Other sea reptiles
Family / clade: Sauropterygia3
Classification: Sauropterygia3
Age of the rocks: 244 to 243 million years ()3
Rock formations: Guanling3
Countries: China3
Fossil records: 2 in the Paleobiology Database3
Discovery: The first fossil of Atopodentatus was found near Daaozi village in Yunnan, China. Scientists named it in 2014. The name means 'unusual tooth' because of its strange teeth.1
Still debated: Scientists are not sure exactly how Atopodentatus is related to other marine reptiles. It is considered a strange type of sauropterygian.2

Where the facts come from

Atopodentatus (en.wikipedia.org)
The earliest herbivorous marine reptile and its remarkable jaw apparatus | Science Advances (science.org)
Atopodentatus 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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