Dino card No. 0377 of 2,027

Cetarthrosaurus

Say it: set-ar-THRO-sore-us

Name means: “joint-tail lizard”1

Ate: MeatIchthyosaursEarly CretaceousNot technically a dinosaur

Cetarthrosaurus was a fast-swimming marine reptile that lived in the seas near what is now England. It looked a bit like a dolphin but was actually an ichthyosaur, not a dinosaur.1 3

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

Lived

106 to 100 million years ago3

Early Cretaceous

Fossils found in

Cambridge Greensand Formation, near Cambridge, United Kingdom1 3

Food

Meat3

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

cool stuff

Fun facts

Cetarthrosaurus lived about 100 million years ago, at the end of the Early Cretaceous period.3

Only one fossil of Cetarthrosaurus has been found, a single femur (thigh bone).2

The fossil was discovered by J. F. Walker near a railway bridge at Ditton, northeast of Cambridge.2

The femur bone was worn and rolled, like a bone tumbled on a beach, before it was buried.2

Harry G. Seeley named Cetarthrosaurus in 1873, based on that single leg bone.1 3

The name Cetarthrosaurus means 'joint-tail lizard', referring to its tail bones.1

AI-made picture of Cetarthrosaurus — An AI-made picture of how Cetarthrosaurus 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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For dino experts

Scientific name: Cetarthrosaurus
Named by: Seeley 18733
Group: Ichthyosaurs
Family / clade: Ichthyosauria3
Classification: Ichthyosauria > Ichthyosauromorpha3
Age of the rocks: 106 to 100 million years (Albian)3
Rock formations: West Melbury Marly Chalk3
Countries: United Kingdom3
Fossil records: 1 in the Paleobiology Database3
Discovery: Cetarthrosaurus was named by Harry G. Seeley in 1873. The only known fossil, a femur, was found by J. F. Walker in the Cambridge Greensand near Ditton, England.1 2
Still debated: Scientists are not sure exactly how big Cetarthrosaurus was, because only one leg bone has been found.2

Where the facts come from

Cetarthrosaurus (en.wikipedia.org)
On Cetarthrosaurus Walkeri (Seeley), an Ichthyosaurian from the Cambridge Upper Greensand (exa.ai)
Cetarthrosaurus 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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