Mesosaurus facts for kids

Quick facts for kids Mesosaurus Temporal range: Permian 299 to 280 million years ago
Mesosaurus tenuidens
Scientific classification
Kingdom:	Animalia
Class:	Sauropsida
Order:	†Mesosauria
Family:	†Mesosauridae

Life restoration of Mesosaurus.

Location of Mesosaurus remains shown in blue.

Mesosaurus was an ancient reptile that lived in the water a very long time ago, during the early Permian period. This was about 299 to 280 million years ago! It was one of the first known reptiles to live in the ocean. Mesosaurus had many special features that helped it live a fully aquatic lifestyle in the water.

Scientists sometimes think of Mesosaurus as an anapsid reptile. However, there is some debate about this. Other experts describe it as a 'parareptile', which is a type of sauropsid.

What was Mesosaurus like?

Mesosaurus was one of the first reptiles to go back to living in the water. This happened after other early animals with four limbs (called tetrapods) had moved onto land.

This ancient reptile was about 1 metre (3.3 ft) long. It had webbed feet, a body shaped for swimming, and a long tail. Its tail might have even had a fin to help it move. Mesosaurus likely pushed itself through the water using its long back legs and flexible tail. Its body could bend easily from side to side. However, it had very thick ribs. These thick ribs would have stopped its body from twisting too much. Fossils show that Mesosaurus gave birth to live young, instead of laying eggs.

Mesosaurus had a small skull with long jaws. Its nostrils were placed on top of its head. This allowed the creature to breathe even when only the very top of its head was above the water. Its teeth were perfect for catching small swimming creatures, like tiny crustaceans.

Where did Mesosaurus live?

Mesosaurus played a big role in proving the idea of continental drift. This is the idea that Earth's continents have moved over millions of years. Fossils of Mesosaurus were found in southern Africa and eastern South America. These two places are very far apart today.

Since Mesosaurus was a coastal animal, it could not have swum across the huge Atlantic Ocean. This meant that Africa and South America must have been joined together a long time ago. The discovery of Mesosaurus fossils in both places helped scientists understand how continents moved apart.

Images for kids

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  Fossil from Brazil

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  Fossil in Milan

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  Fossil in Louisiana

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  Early reconstruction of the skeleton of M. brasiliensis showing many small teeth in the jaws (MacGregor, 1908).

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  Fossil of unhatched juvenile or fetus of Mesosaurus tenuidens (FC-DPV 2504) from Uruguay

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  Skeleton molds in whitish weathering shales of the Whitehill Formation, Keetmanshoop, Namibia

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  Distribution of four Permian and Triassic fossil groups used as biogeographic evidence for continental drift, and land bridging. Location of Mesosaurus remains shown by green squares

See also

In Spanish: Mesosaurus para niños