Fun Umoonasaurus Facts For Kids | Kidadl


Fun Umoonasaurus Facts For Kids

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The Umoonasaurus is an extinct genus of plesiosaur belonging to the family Leptocleididae, which lived approximately 115 million years ago in the Aptian and Albian stages of the Late Cretaceous period. This species was given the nickname 'Eric' and was a relatively smaller dinosaur around 8.2 ft (2.5 m) long. The fossil remains of this genus of Plesiosauria were discovered in 1987 and described by a team led by University of Adelaide paleontologist, Dr. Benjamin Kear in the Opal field near Coober Pedy, in Australia. Shallow seas used to cover this region in the past. From the classification of the opalized fossil, we get to know that they were short-necked, had paddled feet, and had a big plesiosaur skull. They had single-headed ribs and had a dermal caudal fin. The most identifying trait of the Umoonasaurus was the three crest ridges on its skull. 'Eric' is considered to be the most complete opalized fossil known and it is included in the fossil collection at a museum in Australia in 1993 and currently is on display there. The species had a natural marine habitat and they lived in freezing cold temperature polar shallow seas, covering parts of Australia that could tolerate extremely cold temperatures.

For more relatable content, check out these Austroraptor facts and Incisivosaurus facts for kids.

Fun Umoonasaurus Facts For Kids

What did they prey on?

Small bony fish

What did they eat?


Average litter size?


How much did they weigh?


How long were they?

8.2 ft (2.5 m)

How tall were they?


What did they look like?

Small and flat upper body

Skin Type

Scaly skin

What were their main threats?

Change in water temperature and killer sharks

Where were they found?

Freezing cold water and high latitude marine sea environment











Scientific Name

Umoonasaurus demoscyllus

How scary were they?


How loud were they?


How intelligent were they?


Umoonasaurus Interesting Facts

How do you pronounce 'Umoonasaurus '?

To pronounce the word 'Umoonasaurus', it is useful to break the big word into five small words. Pronounciation is 'you-moon-nah-sau-rus'.

What type of dinosaur was an Umoonasaurus?

An Umoonasaurus demoscyllus is an extinct genus of plesiosaur belonging to the family Leptocleididae. This genus is not considered a dinosaur but a kind of marine reptile of the sea. It was a relatively small animal around 8.2 ft (2.5 m) long. The identifying trait of Umoonasaurus dinosaurs which is most common is the three crest ridges on its skull.

In which geological period did the Umoonasaurus roam the earth?

The Umoonasaurus roamed the Earth during the Aptian-Albian stages of the Late Cretaceous period and the genus lived approximately 115 million years ago living in the shallow seas covering parts of what is now Australia.

When did the Umoonasaurus become extinct?

The Umoonasaurus demoscyllus became an extinct Plesiosauria after the Aptian and Albian stages of the Late Cretaceous period. The genus lived approximately 115 million years ago. It is believed that a celestial body crashed into the earth's surface, causing great ecological disturbance. It is believed that this collision caused all dinosaur species to become extinct from the planet due to an unusual rise in temperature. Some reports also show that these dinosaurs were preyed on by killer sharks.

Where did a Umoonasaurus live?

The fossils of Umoonasaurus dionsaurs, the extinct genus of Plesiosaur belonging to the family Leptocleididae, were found in what is Australia. This genus of Plesiosauria was discovered by paleontologist Dr. Benjamin Kear in the Zorba Extension of fossilized opal field near the town of Coober Pedy in Australia. It is believed that this relatively small animal around 8.2 ft (2.5 m) long lived in the shallow seas that were once there.

What was a Umoonasaurus's habitat?

The Umoonasaurus prehistoric wildlife included the cool and high-latitude, inland shallow seas covering regions which are now in Australia. This genus lived approximately 115 million years ago. These regions might have had freezing conditions during the winters because there were glendonites and boulders that have been rafted by ice and have been taken as evidence of the temperature.

Who did a Umoonasaurus live with?

Although a Umoonasaurus was a species of marine reptiles, they co-existed with other water dinosaurs of the genus Plesiosauria. Some of the fossil specimens of plesiosaurs found with them were the Brancasurus, Vectocleidus, Leptocleidus, and Hastanectes.

How long did a Umoonasaurus live?

There are no reports describing the life period of this relatively small animal around 8.2 ft (2.5 m). They went extinct 100.5 million years ago and lived in the shallow seas covering parts of present-day Australia.

How did they reproduce?

The Umoonasaurus demoscyllus was viviparous. They traveled long distances in search of breeding grounds and for mating. The female Umoonasaurus developed the embryos within her body and gave birth to live young offspring. Adult dinosaurs would take care of their young until they were mature and strong.

Umoonasaurus Fun Facts

What did a Umoonasaurus look like?

The most vital description and identifying trait of Umoonasaurus are the three crest ridges on its skull. They were relatively smaller animals around 8.2 ft (2.5 m) in length. The Umoonasaurus skull was triangular in shape and large-sized, and their skull length was 8.7 in (22.2 cm) with a width of 5.1 in (13 cm). Their dental jaw had 10 tooth sockets, with long and sharp teeth. The anterior skull region was composed of the parietals which are lanceolate-shaped like a lance head. The cervical centra region was taller and wider. They had four paddled feet and a flat body. Their ribs were single-headed and they had a dermal caudal fin.

Umoonasaurus facts include that the most identifying trait of Umoonasaurus is the three crest ridges on its skull.
We've been unable to source an image of Umaanosaurus and have used an image of Leptocleidus instead. If you are able to provide us with a royalty-free image of Umaanosaurus, we would be happy to credit you. Please contact us at [email protected].

How many bones did a Umoonasaurus have?

The fossils from the Aptian and Albian stage of the Late Cretaceous period discovered by Dr. Benjamin Kear were almost complete and included most parts of the skull and skeleton, but there is no report on the number of bones the Umoonasaurus had when they were alive.

How did they communicate?

There is no information about how the Umoonasaurus communicated, but some evidence says that they communicated using ultrasonic sounds that created vibrations underwater and alerted the others in the group.

How big was a Umoonasaurus?

The Umoonasaurus demoscyllus was a small-sized plesiosaur. It was a relatively small animal around 8.2 ft (2.5 m) long. They were two times smaller than thresher sharks and twice the size of dwarf crocodiles.

How fast could a Umoonasaurus move?

The Umoonasaurus demoscyllus were fast-swimming marine reptiles, and they could prey easily on fishes. There is no exact record of their speed underwater.

How much did a Umoonasaurus weigh?

In the opal fossil discovered by Dr. Kear, there was no report about the weight of the Umoonasaurus. They were relatively small animals around 8.2 ft (2.5 m) in length and it is speculated that they had a lightweight body as they were marine reptiles.

What were the male and female names of the species?

There is no specific name assigned to the male and female dinosaurs of the Umoonasaurus species.

What would you call a baby Umoonasaurus?

There is no name assigned to the newly born offspring of Umoonasaurus dinosaurs.

What did they eat?

The Umoonasaurus belonged to the carnivore genus of Plesiosauria. They mostly had a diet of fish and fed on schools of small fishes like bony fish and small turtles. In some fossil remains, the stomach region was found with fish bones and gastroliths.

How aggressive were they?

Umoonasaurus dinosaurs fed in small groups and they were fast hunters. There is no evidence of their aggressive nature and were believed to flee when attacked by predators.

Did you know...

In the name 'Umoonasaurus' the word 'Umoona' is the name for the Coober Pedy area, and 'saurus' is a Greek word meaning 'lizard'.

The Umoonasaurus Jurassic World Doomby is one of the creatures in the game 'Jurassic World: The Game'.

When did plesiosaurs go extinct?

The genus of Plesiosauria first appeared in the Rhaetian stage at beginning of the Jurassic period, approximately 203 million years ago. They disappeared at the end of the Cretaceous period almost 66 million years ago, due to adverse changes in the ecology of their natural habitat.

What climate did the Umoonasaurus live in?

The climatic description of Umoonasaurus dinosaurs included freezing cold waters and high latitude shallow seas covering parts of inland Australia.  

Here at Kidadl, we have carefully created lots of interesting family-friendly dinosaur facts for everyone to discover! Learn more about some other dinosaurs from our Atlantosaurus interesting facts and Anserimimus surprising facts pages.

You can even occupy yourself at home by coloring in one of our free printable Umoonasaurus coloring pages.

Main image and second image by Nobu Tamura

Written By
Ayan Banerjee

Content writer Ayan has many interests, including writing, such as travel, and playing music and sport. He is even a drummer in a band. With a degree in nautical science, Ayan is also a member of the Chanakya Literary Committee and on the editorial board of 'The Indian Cadet' magazine. You will find Ayan on the badminton court, playing table tennis, trekking the countryside, or running a marathon when he's not writing.

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