The Heyday of Pangea
Published in the EarthSphere Blog. Feature Image: Endless Oceans Off the West Coast of Pangea (©20222 Archean Enterprises, LLC; ArcheanArt)
The Forgotten Origins series now moves on from the Carboniferous into the end of the Paleozoic Era.
Last Time: Carboniferous Cooling
Circumnavigating the globe by ship is an arduous affair. Like the legendary Ferdinand Magellan, if you start in Europe and head west, you eventually bump into the Americas. A turn to the north will be futile due to Arctic ice, so you head south. Passing by the Caribbean and Central America, you wind your way southward along the eastern coastlines of Brazil and Argentina. Finally, you sneak around Cape Horn, braving the rough and windy seas of the Southern Ocean, enter into the Pacific Ocean, and head northwest.
Life moves along leisurely until you brush against Australia and Indonesia, may even detouring north to China. As you seek your return to Europe, you probably visit India and the Middle East, and eventually, you traverse the length of Africa, zip around the Cape of Good Hope, and make the long journey north to your home port. It’s quite the journey to sail around the globe, with your trip constantly interrupted by large, elongated landmasses.
If you attempted the same journey 270 million years ago during the Permian, you would have taken a simpler path. You would have sailed westward from an equatorial port on the west coast of Pangea and traveled in a straight line until you arrived back on the continent’s east coast. During the Permian, 70 percent of Earth’s surface was covered by water, forming a single continuous ocean. The remaining 30 percent of the surface, covered by dry land, was glued together as our favorite supercontinent, Pangea.
North and South America occupied the equatorial and mid-latitude areas of Pangea’s west coast, and Africa and the Middle East were positioned on the equatorial east coast of the continent.
Who was Doing What?
The Permian Period marked the end of the Paleozoic. It occupied a 47 million year stretch from 299 to 252 million years ago — just a slightly shorter interval than the transition from dinosaurs to smart ape-like creatures called Homo sapiens.
The superfamily Hominoidea popped onto the evolutionary scene about 20 million years ago, and about 19 million years later, Homo sapiens took center stage. So, the Permian Period was twice as long as our entire evolutionary history. No species as intelligent and deliberately negligent as Homo sapiens developed during the Permian, but still, it was quite an important time for animal life in general.
Reptiles came into their own during the Permian, and important lineages developed. Permian protorosaurs were the ancestors of archosaurs, a group that eventually developed into dinosaurs and birds. Closer to home for you and me, the synapsids, reptiles with some mammalian traits, evolved during the Permian. These Permian creatures set the stage for true mammals to develop in the Mesozoic.
The Permian world was ripe for mother nature to experiment. When she discovered ingenious evolutionary innovations, there were plenty of connected lands, free from deep ocean barriers, for the biosphere to spread her success across vast and diverse ecosystems.
The Permian plate tectonic configuration was not quite as simple as initially described above, but there was a considerable amount of mid-continent territory to contend with. When the weather gets cold, mid-continent landscapes are where massive glaciers form. Also, we are all familiar with mid-continent deserts and drylands.
Global cooling at the end of the preceding Carboniferous Period meant the Permian started on a cold note. Pangea was truly a supercontinent, and its lands stretched from the South Pole almost to the North Pole. The ancient Gondwana landmass occupied the southern part of Pangea, providing a vast continental interior from the South Pole to the equator. This configuration promoted the formation of large glacial ice sheets, which persisted from the Carboniferous into the Early Permian.
But the planet eventually warmed, and warm moist climates dominated many areas by the mid-Permian. The climatic conditions became ideal for life to blossom and thrive in both temperate and higher latitude ecosystems. Because Pangea created a formidable north-south land barrier, it affected the flow of ocean currents, deflecting warm waters from the tropics to higher latitudes. This led to milder climates near the north and south polar regions. Perhaps having the same effect as the modern Gulf Stream, which warms the North Atlantic, creating milder climates in Europe than would normally be expected.
But change is the only constant, and by the Late Permian, warm had turned into hot, and desert conditions became widespread. Multiple factors were at play, but geography was a major influencer of local climatic conditions. Pangea was the child of multiple orogenic episodes as tectonic plates collided and extensive mountain belts rose skyward. These mountains affected air currents and weather systems, sometimes cutting off moisture to large inland basins.
Today, ancient Permian rock strata are a major source of evaporite minerals like potash salts. These deposits formed under extremely hot, dry conditions, and they were particularly prevalent in the tropical and subtropical regions of Pangea. The Permian also gifted us lots of oil — a blessing and a curse as we simultaneously satisfy our need for cheap power and radically alter our climate and biosphere.
(Next: The Great Dying)
Permian Period (Source: Britannica)