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Utatsusaurus

Say it: oo-TAT-soo-SORE-us
Name means: “Utatsu lizard”1
Ate: MeatIchthyosaursEarly Triassic to Middle TriassicNot technically a dinosaur

Utatsusaurus was one of the very first ichthyosaurs, a marine reptile that lived in the ocean. It had a long, slender body and swam like an eel, wiggling its whole body. Unlike later ichthyosaurs, it had no dorsal fin on its back.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
252 to 247 million years ago3
Early Triassic to Middle Triassic
Fossils found in
Japan (Miyagi Prefecture), Canada (British Columbia), and USA (Nevada)21
Food
Meat1
Length
2.5 to 3 m1
Weight
57.8 kg1

When did it live?

Triassic
Jurassic
Cretaceous
252 million years ago20114566, the asteroid

How big was it?

How long was it?

Utatsusaurus about 3 m longA dog about 1 mA bicycle about 1.8 mA car about 4.5 mAn elephant, the biggest land animal today about 6.5 m

How heavy was it?

as heavy as 14 house cats
as long as 3 dogs nose to tailas long as 17 bananas end to endas heavy as 12 watermelons

How big was Utatsusaurus compared to YOU?

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

cool stuff

Fun facts

1

Utatsusaurus lived about 248 to 245 million years ago, during the Early Triassic period.1

2

It had about 40 vertebrae in front of its hips, and its backbone was shaped like a cylinder, which helped it swim with an eel-like motion.1

3

Its flippers were small and had five fingers, with extra finger bones (a condition called hyperphalangy).1

4

The first fossil of Utatsusaurus was found in Utatsu-cho, a town in Miyagi Prefecture, Japan, and the dinosaur was named after that place.1

5

Utatsusaurus is one of the most primitive ichthyosaurs, meaning it had many features that later ichthyosaurs lost or changed.1

6

Scientists used computer imagery in 1998 to study the crushed fossils and found that Utatsusaurus is related to lizards, snakes, and crocodiles.1

AI-madeAI-made picture of Utatsusaurus
An AI-made picture of how Utatsusaurus 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 Utatsusaurus

?How big was Utatsusaurus?

Utatsusaurus was about 2.5 to 3 metres long (8.2 to 9.8 feet) and weighed around 57.8 kilograms (127 pounds).1

?What did Utatsusaurus eat?

Utatsusaurus ate fish. Its small, blunt teeth were good for catching and eating them.1

?Where was Utatsusaurus found?

The first fossil was found in Utatsu-cho, Japan (now part of Minamisanriku-cho). Fossils have also been found in British Columbia, Canada.1

?Is Utatsusaurus a dinosaur?

No, Utatsusaurus is not a dinosaur. It is an ichthyosaur, a marine reptile that lived in the ocean.1

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For dino experts

Scientific name
Utatsusaurus
Named by
Shikama and Kamei 19783
Group
Ichthyosaurs
Family / clade
Utatsusauridae3
Classification
Ichthyosauria > Ichthyosauromorpha3
Age of the rocks
252 to 247 million years ()3
Rock formations
Sulphur Mountain, Osawa, Prida3
Countries
Japan, Canada, USA3
Fossil records
5 in the Paleobiology Database3
Discovery
Utatsusaurus was named by Tokio Shikama and Tadao Kamei in 1978, based on a partial skeleton found in the Osawa Formation of Japan.31

Where the facts come from

  1. Utatsusaurus (en.wikipedia.org)
  2. PBDB Taxon (paleobiodb.org)
  3. Utatsusaurus 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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Also from the same time: Early Triassic

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