The mass extinction of 100 Million AD did not just ravage life on land, life in the oceans was profoundly affected too. Active volcanoes filled the sky with ash and dust, cutting out the sunlight for months on end. Acid rain, formed by sulfur compounds belched out by volcanoes, fell continuously into the sea.
The lack of sunlight and the increase of acidity killed off the plankton in the surface waters and led to a catastrophic collapse in the oceanic food chain. Many bony fish (the dominant marine animals for hundreds of millions of years) suddenly died away, along with all kinds of other creatures. Where once the oceans had teemed with life, they became almost barren. But nature does not leave ecological niches vacant for long. The animals that survived the mass extinction did so because they took shelter in the deepest, most remote refuges of the ocean. Once conditions had stabilized, bony fish were mostly replaced by completely new forms of life.
It is now 200 million AD. The planet is dominated by a single, giant landmass called Novopangaea. One continent means one ocean, the Global Ocean, a body of water so vast that its center lies 10,000 miles (16,000 kilometers) from the nearest coast. This uninterrupted expanse of water helps to determine the extreme weather conditions of the planet. The intense heating of the atmosphere at the Equator draws in trade winds from the north and south. These converge and blow westwards along the Equator, driving permanent ocean currents before them. The result is a constant equatorial gyre (an immense circulatory current that involves the whole ocean). The global current makes it easy for sea life to migrate, and so the Global Ocean is populated by very cosmopolitan groups of animals.
As the predominant ocean currents run east to west, there is little water movement between north and south. The cold waters of the South Pole do not mix with the warm waters of the Equator. The result is a steep temperature gradient between high and low latitudes. However, worldwide temperatures are still too high for there to be a polar icecap. This single ocean is a complex environment supporting intricate food chains and highly-evolved species, quite unlike anything known from the reign of humanity.
Sometimes brewing over the Global Ocean are extreme hurricanes called hypercanes, 50 percent stronger than previous hurricanes with 400-kilometer-per-hour winds. The reason for this is because since a supercontinent is always surrounded by a superocean, the energy balance of the globe changes. There is a lot more energy, a much warmer ocean, much more energy is transferred into the atmosphere, creating more powerful storms.