Essay on The End Permian Mass Extinction

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Pages: 25

<b>Introduction</b><br>Think of a world which existed 290 million years ago. As you look out over the terane in front of you, you think that you are on an alien planet. You see volcanoes spewing ash and lava. Beside them is the ocean which is swarming with many different species of echinoderms, bryozoans and brachiopods. As you look down onto the sea floor you are amazed at the countless number of starfish and urchins. Some animals leave you can't even describe and you have no idea even what phylum they belong to. This is a world at its height in diversity of oceanic species. Millions of wonderous species existed at this time in the ocean and most of them will never appear again in earth's history. In the geologic time scale, a million …show more content…
Magaritz et al. (1988) reported that carbon-isotope ratios are known to shift or change at some boundaries associated with a mass extinction event. A shift can occur due to a decrease in plant production following a meteor impact or from a large decrease in sea level that reduces shelf area, exposing the shelf and its accumulated organic carbon to erosion. There are sections examined in the Alps of Italy and Austria that actually show a gradual change in the C-13 content of marine organisms across the PTB. These sections show no dramatic shifts that can be associated with a mass extinction. Thus as you can see, the findings of Clark et al. (1985) and Magaritz et al. (1988) shows geochemical evidence that the mass extinction was a gradual event and not a catastrophic extinction event.<br><br><i>Faunal evidence</i><br>Faunal evidence is much harder to come by and explain that geochemical evidence due to major gaps in the PTB boundary layers. Also marine faunal evidence is much more linear than terrestrial. Yoram Eshet et al. (1995) said that fungal evidence can be used to mark the PTB layer. It can also be used for evidence to show how the extinction event occurred. There is a sharp fungal spike in the PTB layer which is made up of Lueckisporites virkkiae, Endosporites papillatus, and Klausipollenites schaubergeri spores. Yoram Eshet et al. (1995) defined four stages across the Permian-Triassic boundary. Stage one, consisted of low abundances of spores which became