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posted by CoolHand on Wednesday April 01 2020, @03:50PM   Printer-friendly
from the fish-over-dino dept.

In Earth’s largest extinction, land die-offs began long before ocean turnover:

New ages for fossilized vertebrates that lived just after the demise of the fauna that dominated the late Permian show that the ecosystem changes began hundreds of thousands of years earlier on land than in the sea, eventually resulting in the demise of up to 70% of terrestrial vertebrate species. The later marine extinction, in which nearly 95% of ocean species disappeared, may have occurred over the time span of tens of thousands of years.

Though most scientists believe that a series of volcanic eruptions, occurring in large pulses over a period of a million years in what is now Siberia, were the primary cause of the end-Permian extinction, the lag between the land extinction in the Southern Hemisphere and the marine extinction in the Northern Hemisphere suggests different immediate causes.

"Most people thought that the terrestrial collapse started at the same time as the marine collapse, and that it happened at the same time in the Southern Hemisphere and in the Northern Hemisphere," said paleobotanist Cindy Looy, University of California, Berkeley, associate professor of integrative biology. "The fact that the big changes were not synchronous in the Northern and Southern hemispheres has a big effect on hypotheses for what caused the extinction. An extinction in the ocean does not, per se, have to have the same cause or mechanism as an extinction that happened on land."

[...] "For some years now, we have known that -- in contrast to the marine mass extinction -- the pulses of disturbance of life on land continued deep into the Triassic Period. But that the start of the terrestrial turnover happened so long before the marine extinction was a surprise."

In their paper, Looy and an international team of colleagues concluded "that greater consideration should be given to a more gradual, complex, and nuanced transition of terrestrial ecosystems during the Changhsingian (the last part of the Permian) and, possibly, the early Triassic."

Journal Reference:

Robert A. Gastaldo, Sandra L. Kamo, Johann Neveling, John W. Geissman, Cindy V. Looy, Anna M. Martini. The base of the Lystrosaurus Assemblage Zone, Karoo Basin, predates the end-Permian marine extinction. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-15243-7


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  • (Score: 2) by hendrikboom on Thursday April 02 2020, @11:46AM (1 child)

    by hendrikboom (1125) Subscriber Badge on Thursday April 02 2020, @11:46AM (#978274) Homepage Journal

    The delays you mention are of the order of months, decades, or centuries.
    The delay presented in the article is about 300 millenia!
    It does indeed sound like something else is going on.

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  • (Score: 1) by khallow on Thursday April 02 2020, @01:24PM

    by khallow (3766) Subscriber Badge on Thursday April 02 2020, @01:24PM (#978290) Journal
    Yea. I guess I was thinking about how gases and ash from a far northern source would propagate in the atmosphere. If you got a huge eruption every few centuries, it'd be enough time for the ecosystem to recover between each eruption. It's really more a red herring outside of that. I did rampantly speculate [soylentnews.org] about how one could get a double extinction hit on opposite sides of the globe from an asteroid/volcanic eruption combo. The huge asteroid hits first in the Southern Hemisphere, causing local extinctions on that side. Due to its massive size, the impact triggers volcanic eruptions at the antipode which fully emerge hundreds of thousands of years later and wipe ocean-based life.