Fun Thalassomedon Facts For Kids

Iram Ashfaq
Jan 31, 2023 By Iram Ashfaq
Originally Published on Oct 01, 2021
Edited by Katherine Cook
Learn the 15 most exciting Thalassomedon facts for you and your family.
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Age: 3-18
Read time: 7.9 Min

The Thalassomedon haningtoni named by Welles was formally known to be a giant, ancient sea tortoise. However, scientists recently discovered that it may actually have been the world's first swimming plesiosaur!

It lived during Ordovician times and swam more than 100 million years ago in an inland river system called strata-one which stretched from present-day North American zones all the way down into North America.

The Thalassomedon haningtoni was one of the most terrifying plesiosaurs to ever live. It could move at speeds of up to 22 mph (35.4 kph)!

The Thalassomedon haningtoni was a marine plesiosaur that lived in the sea long before any other land-based creature.

That is because it was one of the very few animals to adapt itself not only for life on dry land but underwater as well! The beast had large fins and a tail with flippers near its hind feet similar to what we associate with whales and dolphins.

These dinosaurs were so much like them, you wouldn't have been able to tell there were two different types swimming around at once back then when they roamed Earth's waters during the Late Cretaceous period way over 100 million years ago.

It had large, lizard-like teeth and wasn't always friendly towards other creatures around, especially to other marine animals. It often fed on whales or dolphins!

Sadly this terrifying Plesiosauria went extinct millions of years ago because of natural disasters. Fossils of this creature have been found in Russia and North American regions with their fossils dating back to the Late Cretaceous period.

They were distantly related to ichthyosaurs, but Thalasso was much more basal and resembled Plesiosaurs or Sail-Reefs from today’s oceans. They had long neck vertebrae with boney plates on them as you see on sharks!

Find more exciting and thrilling facts about the Woolungasaurus and Eromangasaurus for kids!

Thalassomedon Interesting Facts

Was the Thalassomedon a dinosaur?

Thalassomedon haningtoni was considered a sea lord plesiosaur of the Western Interior North American zone named by Welles, which was an aquatic reptile with the body and neck of crocodiles.

How do you pronounce 'Thalassomedon'?

The correct pronunciation of this name is 'Tha-las-saw-mee-dawn'.

What type of marine reptile was a Thalassomedon?

The Thalassomedon was a plesiosaur, an ancient sea lord that thrived in warm waters. It had four long necks and two large crocodile-like heads with sharp teeth.

In which geological period did the Thalassomedon live?

The Thalassomedon named by Welles was a marine reptile that lived over 150 million years ago during the Late Cretaceous period. The name 'thalass' comes from Greek meaning 'ocean', so in essence, it means something related to sea life or water-related things like an aquarium!

This is most likely because their fossils have been found all around world oceans, which suggests they swam pretty extensively if not constantly throughout their lifetime!

When did the Thalassomedon become extinct?

The Thalassomedon elasmosaurid was an ancient sea plesiosauria that became extinct around 60 million years ago. The only evidence left of it is their fossilized teeth, skull, and body, which can be found on beaches all over the world including Western Hawaii and Australia!

Where did a Thalassomedon live?

The Thalassomedon was a fish that lived in the ocean and was named by the scientist, Welles. It is not known exactly where it could have come from or how old it may be, but we do know for sure there has only been just a couple of examples ever found.

What was a Thalassomedon's habitat?

Thalassomedons lived in the ocean and they were great swimmers. They could live for days without eating or drinking to make sure that their bodies were always at peak performance!

Who did a Thalassomedon live with?

The Thalassomedon elasmosaurid was a plesiosaur that lived in the deep sea after the Early Cretaceous. Who did it live with?

It's not really clear if there is an answer for this question, but you can imagine them swimming around and seeing who else makes up their home. Probably all those weird reptiles from around the ocean at that time.

How long did a Thalassomedon live?

This species of the Western Interior North America lived for about 40 years on average after the early cretaceous period!

How did they reproduce?

To humans that keep asking for more information about Thalassomedon elasmosaurid mating and egg-laying habits, we have some answers. The males and females mated. The females of this fish were capable of laying between 14-25 eggs at once!

Thalassomedon Fun Facts

What did a Thalassomedon look like?

The Thalassomedon elasmosaurid was a type of sea lord that lived in the sea, and they were often depicted as having large eyes. They also had long hair with what looked like seaweed coming out from their heads!

The Thalassomedon skull was proportionately larger and much stronger. The Thalassomedon was an elusive sea lord that lived in the depths of oceans.

The fossil had a long neck, thick tail, and a hideous skull with large teeth for catching prey or perhaps fighting other more dangerous fishes! The colors of their scales shimmered in the underwater light like they were dipped into one giant gemstone!

Sea monsters are a dime-a-dozen in pop culture, but the Thalassomedon was unlike anything we've ever seen before. It had large elephantine ears and leathery skin that turned an iridescent blue when immersed underwater or after being shocked by lightning—just like some sort of superhero!

The Thalassomedon skeleton of this Plesiosauria was found near long stones in the ocean bed.

How many bones did a Thalassomedon have?

Unlike more common types of marine elasmosaurid animals, which usually contain between 60-80 bones (or less), the Thalassomedon had 440!

How did they communicate?

Scientists like Welles have long been trying to figure out how the Thalassomedon communicated.

Some scientists think they used sound waves just like modern humans do, while others believe that their sense of smell was enhanced by a membrane on the nose which can be opened and closed with a pressure change as well as providing some type for touching or tasting things through this same opening at will.

Scientists debate about whether ancient species such as Thalassomedon could use vocalizations similar in nature to those made today by seals when conveying intentions, however all evidence point towards it having an advanced sense!

How big was a Thalassomedon?

They were 36 ft (11 m) long and 28 ft (8.53 m) tall at their tallest point! These elasmosaurid reptiles are even more impressive when you consider how much time has passed since they last walked this Earth, with many other species that have come into existence in between those two points from smaller fish to elephants.

How fast could a Thalassomedon move?

An elasmosaurid Thalassomedon's speed was faster than the average fish, but not as fast-moving.

At 22 mph (35.4 kph) they could swim from place to place without tiring out or needing much fuel on a long journey!

A speed of 22 mph (35.4 kph) might seem slow when compared with other animals that move at speeds upwards of 25 mph (0.4 kph), but remember this animal evolved in water so it does have advantages over slower-moving species such as whales which require lots of food, just by swimming around looking for things!

How much did a Thalassomedon weigh?

The Thalassomedon weighed 4.41 tons (4000 kg)! This ancient Greek Plesiosauria lived in water after the Early Cretaceous that was 30 C ( 86 F) colder than today's oceans and had teeth as sharp as glass which is used for predators.

Prey included small mammals like dolphins! Despite its size, Thalassoma has been known to bite off more than they could chew because those four rows of conical spines would get you anywhere.

What were the male and female names of the species?

Both females and males elasmosaurid species of this genus from the Cretaceous go by the name Thalassomedon! In general, there are minor differences between males and females of the same species.

Male Thalassomedon were smaller than females, but otherwise, the two sexes had very similar appearances. The Thalassomedonidae family contained only one genus. They were small marine fish and their fossils could be found in both saltwater environments (like along coastlines) as well freshwater ones like rivers or lakes!

What would you call a baby Thalassomedon?

The babies of this genus from Cretaceous named by Welles are popular referred to as baby Thalassomedon. Thalassomedon elasmosaurid babies were small and adorable.

They had soft skin, big eyes that looked like they were full of curiosity or perhaps wonderment?

And what was best about them, their tail! So cute...The first thing you would notice when it came to Thalassominderus infants would not be how attractive the little ones might seem on the outside but rather where did all those freshwater pearls with a huge skull come from each day!

What did they eat?

The genus Thalassomedon diet was piscivorous. Thalassomedon was a fish-eating aquatic animal.

It had an elongated body and neck with four flippers and large eyes that could see clearly underwater, giving it an advantage over other sea creatures when feeding on prey like piscivorous tunas or sharks in their deep habitats off the coast of Greek zones, Western Interior of North America!

How aggressive were they?

This animal genus is best known for being one of the largest and most aggressive creatures to swim in our oceans, coming close behind ichthyosaurs like Plesiosaurus and Megalosaurus. A reconstruction by paleontologist Welles shows how much these ancient reptilian beasts might have looked like today- with long necks connected directly underneath their bodies.

Did you know...

Its name could have been derived from the Greek word 'thalassa' which means 'sea'.

Where were the Thalassomedon's bones found?

The Thalassomedon's bones were discovered off the Greek coast of the Western Interior formation in an area known as Delos.

Ancestors Of The Thalassomedon

A creature thought to be an ancestor of the Thalassomedon? Rhomaleosaurus, with its large finning and swimming abilities.

Here at Kidadl, we have carefully created lots of interesting family-friendly prehistoric animal facts for everyone to discover! Learn more about some other creatures from our Teleosaurus fun facts and Tupuxuara facts pages.

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

Main image by Nobu Tamura

Second image by Ghedo

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Written by Iram Ashfaq

Bachelor of Dental Surgery, Master of Public Health

Iram Ashfaq picture

Iram AshfaqBachelor of Dental Surgery, Master of Public Health

With a Bachelor's degree in Dental Surgery from Shaney Institute of Health Sciences and a Master's degree in Public Health from Imperial College London, Iram is a highly qualified and accomplished writer from Srinagar, India. Over the course of a year, she has acquired multiple writing certifications, focusing on health sciences and research studies. Prior to joining Kidadl, Iram gained valuable experience working as a content writer for Indian firms and interning at a New York-based company. Her expertise and passion for writing shine through in her ability to create compelling content across a variety of topics.

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