Dino card No. 1930 of 2,027

Xenodens

Say it: ZEE-no-denz

Name means: “strange tooth”1

Ate: MeatMosasaursLate CretaceousNot technically a dinosaur

Xenodens was a mosasaur, a giant marine lizard that lived in the sea during the time of dinosaurs. It had a mouth full of flat, blade-like teeth that worked like a saw, just like a shark or a piranha. This helped it slice through fish, squid, and even other sea creatures.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

72 to 66 million years ago2

Late Cretaceous

Fossils found in

Ouled Abdoun Basin, Morocco1 2

Food

Meat1

Length

0.9 to 1.1 m1

estimated from fossil material

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

as long as 2 house cats nose to tailas long as 6 bananas end to end

How big was Xenodens compared to YOU?

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

cool stuff

Fun facts

Xenodens means 'strange tooth' in Greek and Latin, and its species name calminechari means 'like a saw' in Arabic.1

Its teeth were short, flattened, and blade-like, forming a saw-like edge along the jaw. No other land or sea reptile had teeth like this.1

Xenodens lived about 72 to 66 million years ago, near the end of the Age of Dinosaurs.2

Scientists first described Xenodens in 2021 from two upper jaw bones found in a phosphate mine in Morocco.1

Some scientists thought the fossil might be a fake, but CT scans in 2025 showed the teeth were real and naturally attached.1

Xenodens was small for a mosasaur, only about 1 meter (3.3 feet) long. Many other mosasaurs were much bigger.1

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

?Was Xenodens a dinosaur?

No, Xenodens was a mosasaur, a marine lizard that lived in the sea during the time of dinosaurs.1

?How big was Xenodens?

About 1 meter (3.3 feet) long, which is small for a mosasaur.1

?What did Xenodens eat?

It likely ate fish, squid, crustaceans, and scavenged dead marine reptiles, using its saw-like teeth to slice through food.1

?Why did Xenodens have strange teeth?

Its short, flattened, blade-like teeth formed a saw-like edge, similar to dogfish sharks and piranhas, for cutting prey.1

Ask Rex about Xenodens

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Myth buster

Myth: Xenodens was a dinosaur.

Truth: Xenodens was a mosasaur, a type of marine lizard that lived in the ocean. Mosasaurs are not dinosaurs.1

For dino experts

Scientific name: Xenodens
Named by: Longrich et al. 20212
Group: Mosasaurs
Family / clade: Mosasauridae2
Classification: Mosasauroidea2
Age of the rocks: 72 to 66 million years (Maastrichtian)2
Rock formations: Couche III2
Countries: Morocco2
Fossil records: 1 in the Paleobiology Database2
Discovery: Xenodens was named in 2021 by Nick Longrich and colleagues based on a left upper jaw bone bought from a local farmer in Morocco. The fossil came from the Sidi Chennane phosphate mine.1
Still debated: Some scientists still debate whether Xenodens is a real species or a fake fossil, though CT scans support its authenticity.1

Where the facts come from

Xenodens (en.wikipedia.org)
Xenodens 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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