(CN) – The Great Dying, a cataclysmic period 252 million years ago during which more than 90 percent of sea creatures and 70 percent of land vertebrates went extinct, may have taken place over only a few thousand years, according to a study published Wednesday in the Geological Society of America Bulletin.
Earth’s most severe extinction event, the Permian-Triassic extinction eliminated 57 percent of biological families and 83 percent of genera. The event divides the Permian and Triassic geologic periods, and also the Paleozoic and Mesozoic Eras, heralding the appearance of the dinosaurs.
The cause of the massive die-off has been debated for years, and a group of scientists from China, the United States and Canada think that they may be closer to an answer. The group combined new high-resolution radiometric dating of seven closely spaced layers of volcanic material from South China’s Penglaitan Section to study fossils in each layer to determine how quickly the species disappeared.
Results show the duration of the end-Permian mass extinction to be about 31 thousand years, essentially a blink of an eye by geological standards.
The study also suggests Siberian flood-basalt eruptions, along with local intensive volcanic activity that may have started some 420 thousand years before the mass extinction, may have reduced the stability of Late Permian ecosystems to the point where a single extreme incident finally resulted in a sudden ecosystem collapse.
Using the rich Late Permian fossils in the Penglaitan Section, the team of scientists from Chinese Academy of Sciences, MIT, the National Museum of Natural History in Washington and the University of Calgary identified at least 10 major marine fossil groups in the earliest fossil layers. Twenty-nine of the 66 Permian species identified in the section disappeared within or at the top of a single bed of volcanic ash-rich sandstone.
Most important, the scientists found no evidence of “survival interval” where Permian creatures lived long enough to see the Early Triassic. This highly diverse marine ecosystem suddenly vanished during the time a single layer of stone was being deposited.
The quick disappearance of species may indicate that the Great Dying took place even faster than 31,000 years.
“The mass extinction may have occurred in only thousands of years, but the analytical uncertainty of current dating technique prevents us from getting a more meaningful constraint for less than 30,000 years,” said Prof. Shen Shuzhong from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences, the study’s lead author.
The climate shifts involved in the end of the Permian Era were extreme, with estimates the global temperature warmed some 50 degrees Fahrenheit in a relatively short time period. However, the sheer scope of the changes and the massive die-off of species during the Permian present some sobering parallels to current global climate trends.