When I was alive the Atlantic Ocean didn't exist!

I have been asked to choose a favourite object for a new exhibition to celebrate and to show-case the scientific and historical collections of my local University. Today, after a lot of thought I have finally settled on this splendid fossil of a Mesosaur.

Mesosaurus was a small fresh-water reptile, not a dinosaur, that lived about 300 million years ago in the early Permian period. It was a lightly-built, four-legged animal with an elongated head and snout with nostrils near to its eyes, as in most aquatic reptiles. It had a vertically flattened tail that was used for swimming. This half to one metre long carnivore probably ate fish and shrimps. You can see a reconstruction of the living animal here.

Fossil Mesosaurs are found only in Brazil and in Namibia. This distribution, when first described, was difficult to understand since this freshwater animal could not possibly have swum across the Atlantic Ocean, and was one of the first pieces of evidence that led to the development of the theory of continental drift. When these animals were alive the Atlantic Ocean simply did not exist, South America and Southern Africa were joined together in a single land mass called Pangaea. With the passage of millions of years they have drifted to their present positions, carrying with them their cargoes of fossil Mesosaurs.

The idea that continents are not fixed in place, but instead drift around on the Earth's surface, was proposed by the German geologist Alfred Lothar Wegener in his 1915 book, On the Origin of Continents and Oceans. Wegener froze to death while heading an expedition crossing the Greenland ice cap in 1930.