Dino card No. 1723 of 2,027

Styxosaurus

Say it: stix-oh-SORE-us

Name means: “river of the dead lizard”1

Ate: MeatPlesiosaursLate CretaceousNot technically a dinosaur

Styxosaurus was a long-necked marine reptile that swam in the shallow seas that once covered North America. It was not a dinosaur, but a plesiosaur, and it used its sharp teeth to catch fish and squid.1 2

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

Lived

90 to 72 million years ago5

Late Cretaceous

Fossils found in

Kansas, South Dakota, Nebraska, and Wyoming, USA2

Food

Meat5

Length

5 to 7 m2

estimated based on related elasmosaurids

Weight

3.1 tonnes3

estimate for specimen SDSM 451

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 2 cars

as long as 7 dogs nose to tailas long as 39 bananas end to endas heavy as 100 big dogsas heavy as 620 watermelons

How big was Styxosaurus compared to YOU?

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

cool stuff

Fun facts

Styxosaurus had an extremely long neck, with over 60 vertebrae, making it one of the longest necks of any animal that ever lived.2

It lived in the Western Interior Seaway, a huge inland sea that split North America in two during the time of the dinosaurs.2

Some fossils of Styxosaurus were once thought to belong to a different animal called Hydralmosaurus, but scientists now think they are the same.2

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

?How big was Styxosaurus?

About 11.3 metres (37 ft) long and weighed around 3.1 metric tons (3.4 short tons). Its neck alone was about 5.25 metres (17.2 ft) long.4

?What did Styxosaurus eat?

It ate fish, squid, and belemnites. It grabbed slippery prey with its sharp, interlocking teeth and swallowed it whole.4

?When did Styxosaurus live?

It lived during the Late Cretaceous period, about 100 to 72 million years ago.4 5

?Did Styxosaurus have a long neck?

Yes, it had an extremely long neck with over 60 vertebrae, making it one of the longest necks of any animal.4 2

?Is Styxosaurus a dinosaur?

No, it is a plesiosaur, a marine reptile that lived in the sea, not a dinosaur.4

?Where was Styxosaurus found?

Fossils have been found in North America, mainly in Kansas, South Dakota, Nebraska, and Wyoming, in rocks that were once the bottom of a shallow sea.4 5

Ask Rex about Styxosaurus

Rex only answers questions about this page. 3 questions a day.

Rex is an AI and can make mistakes. He runs on servers in the EU and questions are never saved. Never type your name or other personal things.

For dino experts

Scientific name: Styxosaurus
Named by: Welles 19435
Group: Plesiosaurs
Family / clade: Elasmosauridae5
Classification: Plesiosauria > Elasmosauridae > Sauropterygia5
Age of the rocks: 90 to 72 million years (Coniacian / Campanian)5
Rock formations: Pierre Shale, Niobrara5
Countries: USA5
Fossil records: 8 in the Paleobiology Database5
Also known as: Hydralmosaurus (older names now counted as the same animal)5
Still debated: Scientists are still debating exactly how many species of Styxosaurus existed, and whether some fossils belong to this genus or to other elasmosaurids.2

Where the facts come from

PBDB Taxon (paleobiodb.org)
Taxonomic reassessment of Hydralmosaurus as Styxosaurus : new insights on the elasmosaurid neck evolution throughout the Cretaceous (pmc.ncbi.nlm.nih.gov)
Styxosaurus (en.wikipedia.org)
Styxosaurus (en.wikipedia.org)
Styxosaurus 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.

Rex is hungry! Dino Wiki is a dad's project for his dino-loving son, free with no ads. Grown-ups can feed Rex a snack to help keep it online.Feed Rex