Utatsusaurus
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
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Fun facts
Utatsusaurus lived about 248 to 245 million years ago, during the Early Triassic period.1
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
Its flippers were small and had five fingers, with extra finger bones (a condition called hyperphalangy).1
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
Utatsusaurus is one of the most primitive ichthyosaurs, meaning it had many features that later ichthyosaurs lost or changed.1
Scientists used computer imagery in 1998 to study the crushed fossils and found that Utatsusaurus is related to lizards, snakes, and crocodiles.1

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
- Utatsusaurus (en.wikipedia.org)
- PBDB Taxon (paleobiodb.org)
- 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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