Dino card No. 0568 of 2,027

Eidolosaurus

Say it: eye-DOH-lo-SORE-us

Name means: “shadow lizard”1

Ate: MeatMosasaursLate CretaceousNot technically a dinosaur

Eidolosaurus was a marine lizard that swam in the seas during the time of the dinosaurs. It had a long, oar-like tail and lived about 100 to 90 million years ago. Scientists know it from a fossil that is mostly an impression, like a shadow in the rock.2 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

100 to 90 million years ago3

Late Cretaceous

Fossils found in

Slovenia, at a place called Comen3

Food

Meat2

Length

0.21 m1

trunk length (presacral vertebrae)

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

How big was Eidolosaurus compared to YOU?

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cool stuff

Fun facts

Eidolosaurus had a long, broad, oar-like tail, which helped it swim in the sea.1

The fossil is mostly an impression, not solid bones, so scientists call it a 'shadowlike imprint'.1

It had 34 vertebrae in its back, 2 in its hips, and at least 48 in its tail.1

Eidolosaurus is related to other marine lizards like mosasaurs and dolichosaurs, but it is not a dinosaur.2 1

The fossil was found during the demolition of a house, and it was given to scientists by Dr. Trauth.1

AI-made picture of Eidolosaurus — An AI-made picture of how Eidolosaurus 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 might think Eidolosaurus was a dinosaur because it lived long ago.

Truth: Eidolosaurus was a marine lizard, not a dinosaur. Dinosaurs lived on land, and this animal swam in the sea.2

For dino experts

Scientific name: Eidolosaurus
Named by: Nopcsa 19233
Group: Mosasaurs
Family / clade: Aigialosauridae3
Classification: Mosasauroidea3
Age of the rocks: 100 to 90 million years (Cenomanian / Turonian)3
Countries: Slovenia3
Fossil records: 1 in the Paleobiology Database3
Discovery: The fossil was found during the demolition of a house in Slovenia, and Dr. Trauth showed it to Baron Nopcsa. Nopcsa named it Eidolosaurus trauthi in 1923.1
Still debated: Scientists are not sure exactly what Eidolosaurus ate or how it lived, because the fossil is only an impression and not complete bones.2

Where the facts come from

Eidolosaurus and Pachyophis (naturalhistory.si.edu)
PBDB Taxon (paleobiodb.org)
Eidolosaurus 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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