Free Newsletters - Space News - Defense Alert - Environment Report - Energy Monitor
Mass Extinction At The Triassic-Jurassic Boundary
Who did it? Who pulled the trigger, or rather, what pulled the trigger at the Triassic-Jurassic boundary that wiped out 20% of all marine families in Earth's oceans, and, on land, most non-dinosaurian archosaurs, most therapsids, and the last of the large amphibians? Whatever it was, it shot down much of the competition so dinosaurs could later dominate the Earth.
"The Triassic-Jurassic boundary extinction event is one of the 'big five'mass extinctions of the Phanerozoic Eon, profoundly affecting life on land and in the oceans," explained Lawrence Tanner, a Professor of Geography and Geoscience at Bloomsburg University in Pennsylvania.
Tanner presented his ideas on the various extinction theories Wednesday at the "Earth System Processes" meeting in Edinburgh Scotland.
"Ultimately, this presentation concerns our ability to test various hypotheses for the cause of large-scale extinction events of the past," he said.
Tanner will address possible explanations for this event. One is gradual climate change or sea-level change during the Late Triassic, but these explanations fail to explain the suddenness of the extinctions in the marine realm.
Then there's; asteroid impact—however, no impact structure can be tied directly to the Triassic-Jurassic boundary. And the current favorite hypothesis is that flood basalts that constitute the Central Atlantic Magmatic Province erupted.
And the release of CO2 or SO2 aerosols during these eruptions are thought to have caused intense global warming (from the former) or cooling (from the latter).
But Tanner's new data on the isotopic composition of fossil soils of Late Triassic and Early Jurassic age demonstrates that there is no evidence of any change in the CO2 composition of the atmosphere.
So the smoking gun still eludes scientists and the cause of this extinction is still at large. "Other possibilities need to be investigated more fully," Tanner explained.
Dept. of Geography and Geosciences at Bloomsburg University
Geological Society of London
Geological Society of America
Subscribe To SpaceDaily Express
A 200 Million Years Old Die Out
Seattle - May 14, 2001
A mass extinction about 200 million years ago, which destroyed at least half of the species on Earth, happened very quickly and is demonstrated in the fossil record by the collapse of one-celled organisms called protists, according to new research led by a University of Washington paleontologist.
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|