Cambrian explosion News

Massive tectonic shift triggered Cambrian explosion?

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Many sources attribute the development of many complex life forms in the Cambrian to the growth of oxygen.

Now, from Phys.org:

The Cambrian explosion is one of the most significant events in Earth’s 4.5-billion-year history. The surge of evolution led to the sudden appearance of almost all modern animal groups. Fossils from the Cambrian explosion document the rapid evolution of life on Earth, but its cause has been a mystery.

The sudden burst of new life is also called “Darwin’s dilemma” because it appears to contradict Charles Darwin’s hypothesis of gradual evolution by natural selection.

It doesn’t just “appear” to contradict it; it does contradict it. Darwin knew that and suggested that the fossil record, filled in, would show that his theory was correct in the matter. Not so far.

At the boundary between the Precambrian and Cambrian periods, something big happened tectonically that triggered the spreading of shallow ocean water across the continents, which is clearly tied in time and space to the sudden explosion of multicellular, hard-shelled life on the planet,” said Dalziel, a research professor at the Institute for Geophysics and a professor in the Department of Geological Sciences.

Beyond the sea level rise itself, the ancient geologic and geographic changes probably led to a buildup of oxygen in the atmosphere and a change in ocean chemistry, allowing more complex life-forms to evolve, he said. More.

Researcher Ian Dalziel is appropriately cautious about the idea, which involves some different assumptions about early Earth geography than the conventional ones.

Here’s the abstract in Geology:

The geologically abrupt appearance in the fossil record of almost all animal phyla is referred to as the Cambrian radiation or “explosion” of life on Earth. Also known as “Darwin’s dilemma,” because it seemingly posed a major problem for his theory of gradual evolution, it coincided with the initiation of the first of the two principal global marine transgressions of the Phanerozoic. Although now seen as more protracted, it is still one of the most striking and critical events in the history of the biosphere. Almost all paleogeographic reconstructions for the early Cambrian feature a previously isolated Laurentia, the core of ancestral North America. Yet geological evidence from five continents, integrated here for the first time, indicates that the present-day “southern cone” of Laurentia was still attached to the newly amalgamated supercontinent of Gondwanaland into Cambrian times. Laurentia was then isolated by the development of a major deep oceanic connection between the opening Iapetus Ocean basin and the already well-developed paleo-Pacific. As the marine transgression advanced, major changes in ocean chemistry occurred, upwelling generated phosphorite deposits, and the number of fossilized metazoan phyla “exploded” with morphologic disparity between Laurentia and Gondwanaland already established. The development of this deep oceanic gateway, and of an ocean floor–consuming and arc-generating subduction zone along virtually the entire margin of Gondwanaland shortly thereafter, need to be taken into account in consideration of the global environmental and biotic changes associated with the Neoproterozoic-Phanerozoic transition. (paywall)

See also: Did a low oxygen level delay complex life on Earth?

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8 Replies to “Massive tectonic shift triggered Cambrian explosion?

  1. 1
    Andre says:

    This all sounds great, but how does a corrosive gas build things?

  2. 2
    Ragnar says:

    I laughed when I read this. The evolutionists are ALWAYS coming up with something else, some new absurd addition or change to their crack-brained theory in order to counter Intelligent Design. But, as I said, I laughed when I read this because their arguments are so weak it’s laughable.

    Um… how does a moving continent suddenly add new INFORMATION to organisms? (*Still laughing*)

  3. 3
    bornagain77 says:

    ENV also has an article up:

    Low Oxygen Suffocates Darwinian Explanations for the Cambrian Explosion – November 4, 2014
    Excerpt: When the American Association for the Advancement of Science publishes a theory seeking to explain the Cambrian explosion, you can be confident you’re getting some of the best thinking out there. In Science Magazine’s Halloween issue, nine researchers from eight prestigious universities, including Yale, University of Illinois, and Caltech advanced their latest offering on the emergence of nearly twenty new animal body plans in the geological blink of an eye.,,,
    Here’s the response in a nutshell: It’s the environment’s fault that animals didn’t “emerge” sooner. Their ancestors were swimming around gasping for breath. When the environment finally turned up the air, “the evolutionary landscape” was set for animal life to emerge. All that pent-up energy exploded in a profusion of new complex body plans.
    This should be testable. Just put some anaerobic microbes in test tubes with varying levels of oxygen. Watch for ones that evolve into new phyla the fastest. Lenski should try this on some of his E. coli samples.,,,
    http://www.evolutionnews.org/2.....90881.html

  4. 4
    Mung says:

    Next they’ll be telling us us that a massive explosion caused the explosion.

  5. 5
    tjguy says:

    Another idea to throw in the mix?

    What that tells us is that they still have no idea how to solve the problem!

    Else they would not keep on thinking up new possibilities.

  6. 6
    Ragnar says:

    Bornagain77, I like the sarcasm.
    Mung, I like the humor.

  7. 7
    Ragnar says:

    People telling us that random geological events & atmospheric changes create a complex code…? Great wisdom guys!

  8. 8
    velikovskys says:

    Why is it that design advocates are so lacking in curiosity? Just curious.

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