Cambrian explosion Intelligent Design

Bringing the Cambrian mysteries to life

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Marrella, a Burgess Shale Cambrian fossil/Verisimilus (CC-BY-2.5)

Okay, okay, not bringing them to “life” but giving us a much better sense of life over half a billion years ago.

The Canadian Rockies have, it turns out,  many more Cambrian sites than the big 1909 find that lay neglected at the Smithsonian so long:

Each new stop has offered striking views of unfamiliar animals, many already described in high-profile papers: the little fish relative Metaspriggina, a vertebrate ancestor that Caron now speculates clustered in schools; the pincered Tokummia; and the ice cream cone–shaped fossils called hyoliths, which Caron’s Ph.D. student Joseph Moysiuk last year linked to shelled animals called brachiopods, some of which persist today.

New finds in various parts of the world generate new interpretations:

In fossils of the shrimplike Chengjiangocaris kunmingensis from southwest China, for example, “we have this structure that looks almost like a pearl necklace,” running almost head to tail, says Javier Ortega-Hernández, an incoming professor at Harvard. His team, led by Jie Yang at Yunnan University in Kunming, China, argued in 2016 that the necklace is a nerve cord studded with smaller clusters of neurons, themselves sprouting tiny nerve fibers. Living arthropods no longer have those fibers. But today’s velvet worms and priapulid worms do, implying kinship between long-vanished stem arthropods and those groups.

Critics argue that paleontologists such as Ma and Ortega-Hernández overinterpret some fossils, spotting nervous tissues that aren’t there. Many of those structures, the critics say, might just be “halos,” biofilms formed when microbes broke down internal parts like muscles or guts after death. But other researchers are convinced. “If you look at the best-preserved nervous systems, there’s no doubt” that the features are real, says Graham Budd, a paleontologist at Uppsala University in Sweden and an architect of the current stem-and-crown concept. Joshua Sokol, “Cracking the Cambrian” at Science

The Cambrian explosion is mysterious enough that it gets more interesting as we know more about it. Incidentally, we tend to assume that the life forms that did not persist for long or survive the era were failures. But it’s possible they were solving problems that changed or disappeared, so they died along with the problems.

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See also: Researchers: Extreme fluctuations in oxygen levels, not gradual rise, sparked Cambrian explosion

Maverick theory: Cambrian animals remade the environment by generating oxygen

Did a low oxygen level delay complex life on Earth?

There was only a small oxygen jump

Animals didn’t “arise” from oxygenation, they created it, researchers say

Theory on how animals evolved challenged: Some need almost no oxygen

New study: Oxygenic photosynthesis goes back three billion years

Enough O2 long before animals?

Life exploded after slow O2 rise?

So the Cambrian really WAS an explosion then?

and finally,

Researchers: Cambrian explosion was not an explosion after all (When in doubt, insist that nothing happened.)

Also, Steve Meyer’s Darwin’s Doubt

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