SwimExpert
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- Nov 26, 2013
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- #41
The problem is that you are so amazingly ignorant, you have to ask such base questions that you really ought to know the answer to already, considering the way you talk.
Pin-pointing the exact cause (or causes) of the Permian–Triassic extinction event is a difficult undertaking, mostly because the catastrophe occurred over 250 million years ago, and much of the evidence that would have pointed to the cause has either been destroyed by now or is concealed deep within the Earth under many layers of rock. The sea floor is also completely recycled every 200 million years by the ongoing process of plate tectonics and seafloor spreading, thereby leaving no useful indications beneath the ocean. With the fairly significant evidence that scientists have managed to accumulate, several mechanisms have been proposed for the extinction event, including both catastrophic and gradualistic processes (similar to those theorized for the Cretaceous–Paleogene extinction event). The former include large or multiple bolide impact events, increased volcanism, or sudden release of methane hydrates from the sea floor. The latter include sea level change, anoxia, and increasing aridity. Any hypothesis about the cause must explain the selectivity of the event, which primarily affected organisms with calcium carbonate skeletons, the long (4– to 6-million-year) period before recovery started, and the minimal extent of biological mineralization (despite inorganic carbonates being deposited) once the recovery began.
This information is from Abby's beloved Wikipedia, but I'm going to pretend that I just finished reading Wikipedia's sources so I can pretend that I've read things that I haven't.