Dino card No. 1703 of 2,015

Stenopterygius

Say it: sten-op-ter-IJ-ee-us

Name means: “narrow fin”1

Ate: MeatIchthyosaursEarly Jurassic to Middle JurassicNot technically a dinosaur

Stenopterygius was a fast-swimming marine reptile that lived in the Jurassic seas. It looked a bit like a dolphin but was actually an ichthyosaur, not a dinosaur. It had a long beak full of teeth and chased after fish and squid.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

184 to 171 million years ago3

Early Jurassic to Middle Jurassic

Fossils found in

Germany, England, France, Luxembourg and Switzerland1 3

Food

Meat1

Length

2 to 4 m1

young adults about 2 m, largest species up to 4 m

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

cool stuff

Fun facts

Stenopterygius had a small skull and narrow flippers compared to its relative Ichthyosaurus.1

One well-preserved fossil shows traces of skin, revealing that Stenopterygius was countershaded: darker on the back and lighter on the belly.1

Fossils of Stenopterygius often contain the remains of its last meal in the stomach area.1

The tail ended in a large, semicircular, leathery vertical fin, and it also had a triangular dorsal fin on its back.1

Stenopterygius lived during the Early and Middle Jurassic, about 183 to 173 million years ago.1

The type specimen of Stenopterygius quadriscissus is a complete skeleton that even preserved a very large embryo inside.1

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

For dino experts

Scientific name: Stenopterygius
Named by: Jaekel 19043
Group: Ichthyosaurs
Family / clade: Thunnosauria3
Classification: Ichthyosauria > Ichthyosauromorpha3
Age of the rocks: 184 to 171 million years (Toarcian to Aalenian)3
Rock formations: Posidonia Shale, Opalinuston, Beacon Limstone3
Countries: Germany, United Kingdom, Luxembourg, France3
Fossil records: 47 in the Paleobiology Database3
Discovery: The species was first named as Ichthyosaurus quadriscissus by Quenstedt in 1856. Otto Jaekel gave it its own genus, Stenopterygius, in 1904.1
Still debated: Scientists are still debating exactly how many species of Stenopterygius existed, because the fossils are often incomplete.2

Where the facts come from

Stenopterygius (en.wikipedia.org)
First Diagnostic Marine Reptile Remains from the Aalenian (Middle Jurassic): A New Ichthyosaur from Southwestern Germany | PLOS One (journals.plos.org)
Stenopterygius 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.