Dino card No. 1862 of 2,027

Unktaheela

Say it: unk-ta-HEE-la

Name means: “from the Lakota word for a mythical water creature”1

Ate: MeatPlesiosaursLate CretaceousNot technically a dinosaur

Unktaheela was a small, fast-swimming marine reptile that lived in the sea that once covered North America. It had a short neck, a big head with a long snout, and four flippers that worked like paddles. It was one of the smallest plesiosaurs ever found.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

84 to 72 million years ago3

Late Cretaceous

Fossils found in

Wyoming and South Dakota, USA3 1

Food

Meat2

Length

2.3 to 2.6 m2

estimated adult length

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

as long as 2.5 dogs nose to tailas long as 14 bananas end to end

How big was Unktaheela compared to YOU?

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

cool stuff

Fun facts

Unktaheela is the smallest known adult polycotylid plesiosaur, measuring only about 2.3 to 2.6 metres long.2

It had bony ledges over its large eyes that may have shaded them from sunlight, like built-in sunglasses.2

Its skull was wide at the back and short behind the eyes, which helped it spot and catch prey.2

Unktaheela lived about 80 million years ago in the Western Interior Seaway, a shallow sea that split North America in two.2

Scientists think Unktaheela was a visual pursuit predator, meaning it chased its food using its sharp eyesight.2

The first fossil of Unktaheela was found in 1975 near Redbird, Wyoming, but it was not named until 2024.1 2

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

Ask Rex about Unktaheela

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: Unktaheela
Named by: Clark et al. 20243
Group: Plesiosaurs
Family / clade: Polycotylidae3
Classification: Plesiosauria > Sauropterygia3
Age of the rocks: 84 to 72 million years (Campanian)3
Rock formations: Sharon Springs3
Countries: USA3
Fossil records: 2 in the Paleobiology Database3
Discovery: Unktaheela was named in 2024 by Robert O. Clark, F. Robin O'Keefe, and Sara E. Slack based on two fossils from Wyoming and South Dakota.3 1
Still debated: Scientists are still debating exactly how Unktaheela used its unusual eye ledges and wide skull to hunt.2

Where the facts come from

Unktaheela (en.wikipedia.org)
A new genus of small polycotylid plesiosaur from the Upper Cretaceous of the Western Interior Seaway and a clarification of the genus Dolichorhynchops (sciencedirect.com)
Unktaheela 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