pangaea and gorgonopsids -- 4/01/20
Today's selection -- from The Ends of the World by Peter Brannen. Pangaea and gorgonopsids:
"[We take] for granted the idea that the continents have moved around over geologic time. But this idea -- that they drift above an unseen, incandescent conveyor of convecting rock -- is one of the most revolutionary ideas in the history of science. Amazingly, it's gained widespread acceptance only about as recently as artificial sweetener. And like most scientific revolutions, it began its life as disreputable, bordering on crazy, speculation.
"The theory of continental drift was most famously developed by Alfred Wegener, a German meteorologist whose studies brought him, as most scientific pursuits did at the turn of the twentieth century, to the high Arctic. On expeditions to Greenland, he developed a vision of the continents as similar to the great ice floes that surrounded him: calving apart, drifting and crashing into each other over great expanses of time, and at one point forming a supercontinent in the deep past that he called Pangaea, meaning 'all earth.' Wegener came to this revelation by making the same observation that most six-year-olds do: that the continents roughly fit together, like puzzle pieces. On top of that, fossils seem to form bands that jump the oceans and connect disparate parts of the world by prehistoric biology. Despite the persuasive case he made, Wegener was roundly dismissed by his contemporaries and didn't live to see his vindication. Like all good Victorian Arctic explorers, he died valiantly on the ice, where he remains today, buried under perhaps 100 feet of snow.
"The idea Wegener left behind, continental drift, would eventually upend all of geology. The state of the science before midcentury was not unlike that of astronomy before the conceptual revolutions of Galileo and Copernicus, and explanations of the planet's geological features shared the same tortured logic of Ptolemy's epicycles. But when bathymetric surveys of the seafloor in the late 1950s and early '60s showed gigantic underwater volcanic mountain ranges encircling the world like the seams of a baseball, pushing the continents apart, suddenly everything in geology made sense: volcanoes, earthquakes, island arcs, mountain ranges, deep-sea trenches, the distribution of fossils, and the strange complementary borders of the continents, which were indeed once united in a globe-spanning supercontinent hundreds of millions of years ago -- just as Wegener had surmised. This supercontinent, Pangaea, reached its apotheosis in the Permian, when it formed a giant splayed C that stretched from the Arctic to the Antarctic, interrupted in the middle by a titanic east-west mountain range where North America met Africa and South America. The supercontinent was surrounded by a global super-ocean to match, called Panthalassa.
"While the rhinolike herbivores munched on their unappealing Pangaean shrubs, the kings and queens of the supercontinent were yet another ancient relative of ours: the menacing gorgonopsids -- brawny and vaguely wolflike apex predators with skulls like giant staple removers and teeth longer than those of T. rex. These fearsome daggers, which they used to tear the plant-eating dicynodonts limb from limb, included incisors, canines, and postcanines, indicating a lineage inching closer to mammaldom. The gorgonopsids are aptly named for the mythical Greek sisters the Gorgons, who could turn people to stone with their gaze alone. All these long-lost cousins of ours -- dicynodonts and gorgonopsids, herbivore and carnivore alike -- ruled the world for the final 10 million years of the Paleozoic."