Dino card No. 0927 of 2,027

Jormungandr

Say it: jor-MUN-gand

Name means: “named after Jǫrmungandr, the giant sea serpent from Norse mythology”1

Ate: MeatMosasaursLate CretaceousNot technically a dinosaur

Jormungandr was a huge, swimming lizard that lived in the sea during the time of dinosaurs. It had a long body, strong jaws, and sharp teeth for catching fish and other sea creatures. This marine reptile was not a dinosaur, but a fierce predator of the ancient oceans.1

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

Lived

84 to 72 million years ago2

Late Cretaceous

Fossils found in

Cavalier County, North Dakota, USA2 1

Food

Meat2 1

Length

5.4 to 7.3 m1

estimated from skull size

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

as long as 7 dogs nose to tailas long as 41 bananas end to end

How big was Jormungandr compared to YOU?

Just maths in your browser. Nothing is saved or sent anywhere.

cool stuff

Fun facts

Jormungandr's skull was about 72 centimeters (28 inches) long, and its lower jaw measured 80.8 centimeters (31.8 inches).1

The fossil was discovered in 2015 by a fossil collector named Deborah Shepherd near Walhalla, North Dakota.1

Jormungandr lived about 80 million years ago, during the Late Cretaceous period.1

The fourth dorsal vertebra of Jormungandr has marks that scientists think are bite marks from another mosasaur, possibly from a fight or scavenging.1

Jormungandr shares features with both primitive mosasaurs like Clidastes and more advanced ones like Mosasaurus, making it a 'missing link' in mosasaur evolution.1

The species name walhallaensis comes from the town of Walhalla, which is named after Valhalla, the hall of slain warriors in Norse mythology.1

AI-made picture of Jormungandr — An AI-made picture of how Jormungandr 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.

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Myth buster

Myth: Some people think Jormungandr was a dinosaur.

Truth: Jormungandr was a mosasaur, a type of marine lizard, not a dinosaur. Mosasaurs are reptiles but belong to a different group than dinosaurs.1

For dino experts

Scientific name: Jormungandr
Named by: Zietlow et al. 20232
Group: Mosasaurs
Family / clade: Mosasauridae2
Classification: Mosasauroidea2
Age of the rocks: 84 to 72 million years (Campanian)2
Rock formations: Pierre Shale2
Countries: USA2
Fossil records: 1 in the Paleobiology Database2
Discovery: The only known fossil of Jormungandr was found in 2015 by fossil collector Deborah Shepherd near Walhalla, North Dakota. It was later described and named by paleontologists Amelia Zietlow, Clint Boyd, and Nathan Van Vranken in 2023.1
Still debated: Scientists are not sure if Jormungandr is a distinct genus or just a new species of Clidastes. Some researchers think it might be renamed Clidastes walhallaensis in the future.1

Where the facts come from

Jormungandr walhallaensis (en.wikipedia.org)
Jormungandr 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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