Recent Changes

Wednesday, December 9

  1. page Problem 5 - Climate Change edited ... An analysis of the final stratigraphic appearances of byrozoan species and genera, compiled in…
    ...
    An analysis of the final stratigraphic appearances of byrozoan species and genera, compiled in a world-wide bryozoan data base, revealed three discrete Late Ordovician extinctions. A Late Carddoc (Onnian) extinction was most pronounced on the plates of Baltica and Siberia. Endemic species and genera, confined to one plate and one lithotope were most affected and the extinction was coincident with increased migrations of bryozoan genera to Baltica and Siberia. The Late Caradoc extinction may be related to decreasing provinciality and competition between migrant and stenotopic taxa. Two major extinctions occurred in the Late Ashgill. The greatest of the two is recognized at the end of the Rawtheyan. and affected primarily taxa on the North American plate. The extinction at the end of the Hirnantian affected primarily Baltic taxa. The exact timing of the end-Rawtheyan extinction in North America cannot be established owing to incompleteness of the stratigraphic record. The Rawtheyan extinction occurred during a major glaciation centered in North Africa and a regression of epeiric seas. The large majority of North American survivors of the extinction are represented by Faunas preserved on Anticosti Island. which remained submerged during the regression. This evidence supports regression as a cause of the Rawtheyan extinctions in North America. The end-Hirnantian extinctions may be related to the ensuing transgression or to a wave of faunal migrations associated with the transgression. *Bryozoa, extinctions, Ordovician, Rawtheyan, Hirnantian, North America, Baltica.
    http://www3.interscience.wiley.com/journal/119321192/abstract?CRETRY=1&SRETRY=0
    The Permian period was between 290 Ma and 250 Ma.
    At that time the land was in one mass called a supercontinent. This supercontinent was PANGEA.
    95% of all marine life on earth was killed.
    70% of all land families became extinct.

    (view changes)
    9:07 am
  2. page Problem 5 - Climate Change edited ... Ordovician Extinction: Magnitude of PT extinction: ... tomorrow. )) {H2S-extinction-Sc…
    ...
    Ordovician Extinction:
    Magnitude of PT extinction:
    ...
    tomorrow. ))
    {H2S-extinction-SciAm.pdf}
    Impact from the Deep
    ...
    (page 10 has discussion of massive volcanic eruption coinciding with extinction)
    http://books.google.com/books?hl=en&lr=&id=wfrPf9Hqp1gC&oi=fnd&pg=PP13&dq=mass+extinction+251+million+years+ago&ots=X1UEpV0RVL&sig=OoWTIvdv6oWBzpsBNY81vgls6so#v=onepage&q=mass%20extinction%20251%20million%20years%20ago&f=false
    ABSTRACT
    An analysis of the final stratigraphic appearances of byrozoan species and genera, compiled in a world-wide bryozoan data base, revealed three discrete Late Ordovician extinctions. A Late Carddoc (Onnian) extinction was most pronounced on the plates of Baltica and Siberia. Endemic species and genera, confined to one plate and one lithotope were most affected and the extinction was coincident with increased migrations of bryozoan genera to Baltica and Siberia. The Late Caradoc extinction may be related to decreasing provinciality and competition between migrant and stenotopic taxa. Two major extinctions occurred in the Late Ashgill. The greatest of the two is recognized at the end of the Rawtheyan. and affected primarily taxa on the North American plate. The extinction at the end of the Hirnantian affected primarily Baltic taxa. The exact timing of the end-Rawtheyan extinction in North America cannot be established owing to incompleteness of the stratigraphic record. The Rawtheyan extinction occurred during a major glaciation centered in North Africa and a regression of epeiric seas. The large majority of North American survivors of the extinction are represented by Faunas preserved on Anticosti Island. which remained submerged during the regression. This evidence supports regression as a cause of the Rawtheyan extinctions in North America. The end-Hirnantian extinctions may be related to the ensuing transgression or to a wave of faunal migrations associated with the transgression. *Bryozoa, extinctions, Ordovician, Rawtheyan, Hirnantian, North America, Baltica.
    http://www3.interscience.wiley.com/journal/119321192/abstract?CRETRY=1&SRETRY=0

    (view changes)
    9:05 am

Tuesday, December 8

  1. page Problem 5 - Climate Change edited ... Each possible cause led to another, creating a chained sequence, almost like a domino effect, …
    ...
    Each possible cause led to another, creating a chained sequence, almost like a domino effect, with each event being more extreme than the previous. This results in a comination of catastrophic events that ultimately caused the mass extinction.
    Ordovician Extinction:
    Magnitude of PT extinction:
    ((I have some good comparative figures, but I can't get them on here so I will give them to you in the library tomorrow. ))

    {H2S-extinction-SciAm.pdf}
    Impact from the Deep
    (view changes)
    6:45 pm
  2. page Problem 5 - Climate Change edited ... Talk about how PT is the biggest extinction, the percents of extinction, and the variety and n…
    ...
    Talk about how PT is the biggest extinction, the percents of extinction, and the variety and names of some organisms killed. talk about Panthalassa Sea.
    Theories for extinction (in multiple slides):
    ...
    UV radiation. (Cool term: ever-worsening positive-feedback loop, the "runaway-greenhouse")
    Then Ordovician extinction: smaller part of presentation. Global cooling --> glaciation --> dropped sea levels, etc.
    Then summarize the main differences in causes and effects of the two extinctions (also that the Permian was at least twice the magnitude of the Ordovician extinction, the second biggest).
    (view changes)
    6:38 pm
  3. page Problem 5 - Climate Change edited ... Volcanism à CO2 emissions à global warming. Then introduce anoxia, and how global warming affe…
    ...
    Volcanism à CO2 emissions à global warming. Then introduce anoxia, and how global warming affects that in the oceans: high temperatures + deep sea Anoxia à H2S (poisonous) à depleted ozone à UV radiation.
    Then Ordovician extinction: smaller part of presentation. Global cooling --> glaciation --> dropped sea levels, etc.
    ...
    the two extinctions.extinctions (also that the Permian was at least twice the magnitude of the Ordovician extinction, the second biggest).
    Then talk about today's conditions... And compare, concluding on which extinction would be more likely to occur today (PT is what I've gathered I think).
    zgentes"Over the past century and a half paleontologists have used ammonoids, bivalves, and now conodonts to progressively divide the Permian and Triassic into a sequence of series, stages, and at the finest level of detail, biostratigraphic zones" (Erwin)
    The end-Permian extinction marks the end of marine communities dominated by the sessile, epifaunal filter-feeding articulate braciopods, bryozoans, crinoids, and other pelmatazoan echinoderms, but this extinction also led to evolutionary opportunities and more mobile marine organisms (such as mollusks).
    Information we need:
    How/Why. What are the processes involved with these two extinctions? How are they different?
    (view changes)
    6:27 pm
  4. page Problem 5 - Climate Change edited ... definitely start with the PT extinction, because he said that should comprise 60 to 70 percent…
    ...
    definitely start with the PT extinction, because he said that should comprise 60 to 70 percent of the presentation.
    Talk about how PT is the biggest extinction, the percents of extinction, and the variety and names of some organisms killed. talk about Panthalassa Sea.
    ...
    multiple slides):
    Volcanism à CO2 emissions à global warming. Then introduce anoxia, and how global warming affects that in the oceans: high temperatures + deep sea Anoxia à H2S (poisonous) à depleted ozone à UV radiation.
    Then Ordovician extinction: smaller part of presentation. Global cooling --> glaciation --> dropped sea levels, etc.
    Then summarize the main differences in causes and effects of the two extinctions.
    Then talk about today's conditions... And compare, concluding on which extinction would be more likely to occur today (PT is what I've gathered I think).
    zgentes"Over the past century and a half paleontologists have used ammonoids, bivalves, and now conodonts to progressively divide the Permian and Triassic into a sequence of series, stages, and at the finest level of detail, biostratigraphic zones" (Erwin)
    Information we need:
    How/Why. What are the processes involved with these two extinctions? How are they different?
    (view changes)
    6:15 pm
  5. page Problem 5 - Climate Change edited ... Anoxia: A total decrease in the oxygen levels; an extreme decrease in oxygen availability. htt…
    ...
    Anoxia: A total decrease in the oxygen levels; an extreme decrease in oxygen availability. http://en.wikipedia.org/wiki/Anoxia
    Any suggestions on organization for the PowerPoint?
    (zoe:)
    Perhaps start out with an overview of the 5 major mass extinctions in history you listed, and talk about impact causes versus biotic and ecological causes for extinction. Then say we will talk about the PT and the Ordovician.
    definitely start with the PT extinction, because he said that should comprise 60 to 70 percent of the presentation.
    Talk about how PT is the biggest extinction, the percents of extinction, and the variety and names of some organisms killed. talk about Panthalassa Sea.
    Theories for extinction (in multiple slides):
    Volcanism à CO2 emissions à global warming. Then introduce anoxia, and how global warming affects that in the oceans: high temperatures + deep sea Anoxia à H2S (poisonous) à depleted ozone à UV radiation.
    Then Ordovician extinction: smaller part of presentation. Global cooling --> glaciation --> dropped sea levels, etc.
    Then summarize the main differences in causes and effects of the two extinctions.
    Then talk about today's conditions... And compare, concluding on which extinction would be more likely to occur today (PT is what I've gathered I think).

    Information we need:
    How/Why. What are the processes involved with these two extinctions? How are they different?
    (view changes)
    5:50 pm
  6. page Problem 5 - Climate Change edited ... Does animals and plants going extinct somehow fit into global carbon cycling and CO2 in the at…
    ...
    Does animals and plants going extinct somehow fit into global carbon cycling and CO2 in the atmosphere? And where would H2S fit into that?
    Anoxia: A total decrease in the oxygen levels; an extreme decrease in oxygen availability. http://en.wikipedia.org/wiki/Anoxia
    Any suggestions on organization for the PowerPoint?
    Information we need:
    How/Why. What are the processes involved with these two extinctions? How are they different?
    (view changes)
    4:50 pm
  7. page Problem 5 - Climate Change edited ... There is evidence found in oceanic sediments from the Late Permian to Late Triassic, which yie…
    ...
    There is evidence found in oceanic sediments from the Late Permian to Late Triassic, which yielded chemical evidence of an ocean-wide spread of the H2S bacteria. This evidence was also found in strata from the once-shallow marine settings of the P/T boundary, which suggests that a lack of oxygen also reached the surfaces.
    Note: These microbes can only survive in an oxygen-free environment, however they do need sunlight for their photosynthesis.
    "The end-Permian mass extinction coincides with one of the most massive volcanic eruptions of the past 600 million years.... Global cooling from erupted dust, followed by global warming from clouds of carbon dioxide and acid rain from billowing sulfur are commonly proposed links between volcanism and extinction, but are difficult to test." (Erwin, Douglas H., 2006, Extinction: how life on earth nearly ended 250 million years ago, Princeton University Press, Princeton, New Jersey, pp.10-15)
    There is no solid evidence of an impact event.
    "...The various anoxia hypotheses (there are at least three) suffer from an inability to explain the terrestrial extinciton." (Erwin, Douglas H., 2006, Extinction: how life on earth nearly ended 250 million years ago, Princeton University Press, Princeton, New Jersey, pp.10-15)
    The P/T mass extinction is similar to the Cretaceous-Teriaty mass extinction.

    ------------------------------------------------------------------------------
    H2S (Hydrogen Sulfide)
    (view changes)
    4:21 pm
  8. page Problem 5 - Climate Change edited ... Causes/Theories for Extinctions P/T Extinction: (from wikipedia) Impact The evidence of …
    ...
    Causes/Theories for Extinctions
    P/T Extinction:
    (from wikipedia)
    Impact
    The evidence of an impact for the C/T extinction led geologists to speculate that such events may have played a part in other mass extinctions, including the P/T extinction.
    (view changes)
    4:11 pm

More