Prehistoric Animal Museum

Meet today’s friendMarine reptile; plesiosaur

Styxosaurus

A long neck, a small head and four flippers.

Find Styxosaurus’s small head, then follow its long neck with your eyes all the way to its body. Four flippers sit along its sides, like four little paddles for moving through the water.

Still model of Styxosaurus on a transparent background

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Styxosaurus

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Preparing the Styxosaurus exhibit.

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Guide for grown-ups

When it lived: Late Cretaceous
Where fossils were found: Western Interior Seaway, North America
Body length: 10.7 m (about 35 ft)
Diet: Meat-eater
What kind of animal?: Marine reptile; plesiosaur. Styxosaurus was a marine reptile in the plesiosaur group. A long neck led to its small head, and four flippers grew along its sides.

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Narration transcript

Find Styxosaurus’s small head, then follow its long neck with your eyes all the way to its body. Four flippers sit along its sides, like four little paddles for moving through the water.

Research notes about Styxosaurus

Research summary

Fossils of Styxosaurus date to the Late Cretaceous and have been found in Western Interior Seaway, North America.

Learning from fossils

Its full body length and the shape of its tail tip have to be reconstructed from the surviving fossils.

Scientific sources

Styxosaurus at the Museum of GeologyAccessed 2026-10-22

Leon Made This compiled these research notes from public museum resources and scientific papers while preserving uncertainty in the reconstruction. Last reviewed 2026-10-22.

3D model and asset credits

Styxosaurus snowii: “Styxosaurus snowii” by Julian Johnson-Mortimer, CC BY 4.0; modified for the Prehistoric Animal Museum. Creative Commons Attribution 4.0 International

Open source and licensing

The code is licensed under AGPL-3.0. Original science writing and project artwork use CC BY-NC-SA 4.0 for non-commercial sharing. The brand policy prevents impersonation, and third-party assets keep their original licences.

View the GitHub project Read the full licensing notes

Official source

Made by Leon Made This

Prehistoric Animal Museum is made and maintained by Leon Made This. Use these addresses to verify the official project and its creator.

Official Prehistoric Animal Museumhttps://leon-made-this.work/museum/en/Leon's personal websitehttps://leon-made-this.work/

More information is available below.

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Leon Made This

About this museum

A little museum made by a developer dad for his daughter

I’m Leon, a developer and a dad. When my daughter was three, dinosaur chases on television frightened her, so I made a 3D prehistoric animal museum where she could look quietly and listen only when she wanted to.

The museum is free, with no sign-up, adverts or visitor tracking. Finding one interesting detail at a time is plenty.

Official source

Made by Leon Made This

Prehistoric Animal Museum is made and maintained by Leon Made This. Use these addresses to verify the official project and its creator.

Official Prehistoric Animal Museumhttps://leon-made-this.work/museum/en/Leon's personal websitehttps://leon-made-this.work/

View the source on GitHub Read the licence and asset notes