Dino card No. 1177 of 2,027

Microcleidus

Say it: MY-kro-KLY-dus

Name means: “small collarbone”5

Ate: MeatPlesiosaursEarly JurassicNot technically a dinosaur

Microcleidus was a long-necked marine reptile that swam in the warm Jurassic seas. It had a small head and a very long neck with 38 to 39 bones. It used its flippers to paddle through the water and catch fish.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 175 million years ago5

Early Jurassic

Fossils found in

England, Germany, France, and Luxembourg5

Food

Meat5

Length

4.27 to 5.03 m1

estimated from two specimens

Weight

120 kg to 650 kg3 4

range across species: M. melusinae 120 kg, M. tournemirensis 300 kg, M. homalospondylus 650 kg

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

How heavy was it?

as heavy as 22 big dogs

as long as 5 dogs nose to tailas long as 28 bananas end to endas heavy as 130 watermelons

How big was Microcleidus compared to YOU?

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

cool stuff

Fun facts

Microcleidus had a small head only about 23 centimetres (9 inches) long, even though its body could reach over 5 metres.1

Its neck contained 38 to 39 vertebrae, making it a very long-necked plesiosaur.1

Scientists have named at least five species of Microcleidus, including M. homalospondylus and M. macropterus.1

One species, Microcleidus tournemirensis, was once thought to belong to a different genus called Occitanosaurus.5

Microcleidus lived during the Toarcian age of the Jurassic Period, about 184 to 175 million years ago.2

Its fossils have been found in the Alum Shale of England and the Posidonia Shale of Germany.5

The first Microcleidus fossils were originally described as Plesiosaurus homalospondylus by Richard Owen in 1865.1

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

?How big was Microcleidus?

The largest species, Microcleidus homalospondylus, measured about 5.1 metres (17 feet) long and weighed around 650 kilograms (1,430 pounds). Other species were smaller, like M. tournemirensis at about 4 metres (13 feet) and 300 kilograms (660 pounds).3

?What did Microcleidus eat?

Microcleidus was a carnivore that likely ate fish and other small sea creatures. It used its long neck and small head to snap up prey while swimming.5

?Where did Microcleidus live?

Microcleidus lived in the warm Jurassic seas, and its fossils have been found in England, Germany, France, and Luxembourg. It swam in shallow waters about 184 to 175 million years ago.3 5

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For dino experts

Scientific name: Microcleidus
Named by: Watson 19095
Group: Plesiosaurs
Family / clade: Microcleididae5
Classification: Plesiosauria > Sauropterygia5
Age of the rocks: 184 to 175 million years (Toarcian)5
Rock formations: Alum Shale, Posidonia Shale5
Countries: United Kingdom, Germany, France, Luxembourg5
Fossil records: 9 in the Paleobiology Database5
Also known as: Occitanosaurus (older names now counted as the same animal)5
Discovery: The name Microcleidus was given by D. M. S. Watson in 1909 for fossils that had earlier been called Plesiosaurus. The first species, M. homalospondylus, was originally described by Richard Owen in 1865.5 1
Still debated: Scientists are not sure whether some species, like Hydrorion brachypterygius, should really be placed in Microcleidus.1

Where the facts come from

Microcleidus, Plesiosaur Directory (plesiosauria.com)
PBDB Taxon (paleobiodb.org)
Microcleidus (en.wikipedia.org)
Microcleidus (en.wikipedia.org)
Microcleidus 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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