The Tethys Ocean was a vast body of water that existed during the Mesozoic Era, roughly between 250 and 65 million years ago. It separated the ancient continents of Gondwana to the south and Laurasia to the north. The ocean played a crucial role in the development of marine life and the distribution of species during this time. Over millions of years, the Tethys Ocean gradually closed due to the movement of tectonic plates. This process contributed to the formation of mountain ranges, such as the Himalayas and the Alps, as the oceanic crust was pushed upward. Today, remnants of the Tethys can be found in the Mediterranean Sea and other smaller bodies of water.