Seed-producing gymnosperms, which include the conifers and the cycads, begin to replace lycophytes as the dominant plant group. In the oceans, brachiopods , ammonoids , crinoids , bony fishes, and sharks still thrive, but rugose corals , tabulate corals , and trilobite populations are on the wane. A catastrophic extinction near the close of the period -- several times worse than any other -- nearly ends the entirety of life on land and in the seas. With a stout trunk and leafy crown, cycads provide vegetation and canopy cover to animals.
Cycad fossils -- leaves, stems, cones, and seeds -- are found on every continent, suggesting these gymnosperms thrived in diverse climates over time. Modern species exist only in tropical regions, however. By the early Permian, Earth's major land masses -- Gondwana, Laurussia, and Siberia -- fuse with smaller continents to form the supercontinent Pangaea. Pangaea, which means "all the Earth," stretches nearly from pole to pole.
Where plates converge, crust folds and mountains form. Pangaea is surrounded almost entirely by a massive ocean, Panthalassa. A secondary body of water, the Tethys Ocean, cuts into the east of Pangaea near the equator. Aside from altering the visual landscape, mountain building greatly influences climate.
Pangaea's vast interior becomes increasingly dry. Shielded from the moderating effects of coastal waters, temperatures fluctuate wildly from season to season. Mammal-like reptiles are cold-blooded, but they spawn true, warm-blooded mammalian successors. They are the dominant land vertebrates during the Permian, but despite their early success, only two families will survive into the next period.
Cretaceous: Jurassic: Triassic: Permian: Pennsylvanian: Mississippian: Devonian: Silurian: Ordovician: Cambrian: to Explore This Park. Article Permian Period— NPS image Introduction In British geologist Roderick Impey Murchison named this system from the province of Perm in Russia, where it consists of a great thickness of limestone overlying Carboniferous strata. Learn about what events during the Permian Period Pangaea.
The open part of the letter cupped the Tethys Ocean. Some scientists think a series of volcanic eruptions pumped so much debris into the atmosphere that the sun was blocked out, causing a significant drop in temperature and preventing plant photosynthesis, which in turn caused food chains to collapse.
Other scientists point to global climate change , citing evidence for a period of sudden warming and cooling. These rapid extremes of conditions may have meant species were unable to adjust. Other theories include a catastrophic release of methane gas stored under the seabed, triggered by earthquakes or global warming, or a massive asteroid impact.
Perhaps a combination of factors was to blame. But whatever the cause, new animals and plants would evolve to fill the void. Not least among them: the dinosaurs. All rights reserved. Edaphosaurus A sail-backed edaphosaurus forages amid a Permian landscape in this artist's depiction. Animal Development Being cold-blooded, reptiles had to find ways to deal with big daily variations in temperature, from below freezing at night to over degrees Fahrenheit 38 degrees Celsius during the day.
Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets. India bets its energy future on solar—in ways both small and big. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country.
Epic floods leave South Sudanese to face disease and starvation. Travel 5 pandemic tech innovations that will change travel forever These digital innovations will make your next trip safer and more efficient.
Researchers ran a climate model with Earth's configuration during the Permian, when the land masses were combined in the supercontinent of Pangaea. Before ongoing volcanic eruptions in Siberia created a greenhouse-gas planet, oceans had temperatures and oxygen levels similar to today's. The researchers then raised greenhouse gases in the model to the level required to make tropical ocean temperatures at the surface some 10 degrees Celsius 20 degrees Fahrenheit higher, matching conditions at that time.
The model reproduces the resulting dramatic changes in the oceans. Oceans lost about 80 percent of their oxygen. About half the oceans' seafloor, mostly at deeper depths, became completely oxygen-free. To analyze the effects on marine species, the researchers considered the varying oxygen and temperature sensitivities of 61 modern marine species — including crustaceans, fish, shellfish, corals and sharks — using published lab measurements.
The tolerance of modern animals to high temperature and low oxygen is expected to be similar to Permian animals because they had evolved under similar environmental conditions. The researchers then combined the species' traits with the paleoclimate simulations to predict the geography of the extinction. Many species that lived in the tropics also went extinct in the model, but it predicts that high-latitude species, especially those with high oxygen demands, were nearly completely wiped out.
This illustration shows the percentage of marine animals that went extinct at the end of the Permian era by latitude, from the model black line and from the fossil record blue dots. A greater percentage of marine animals survived in the tropics than at the poles. The color of the water shows the temperature change, with red being most severe warming and yellow less warming.
At the top is the supercontinent Pangaea, with massive volcanic eruptions emitting carbon dioxide.
0コメント