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Wednesday, December 22, 2010

We've completed the set!: All phyla of life appeared in the Cambrian

Confronting the impact of the Cambrian explosion of life 550 million years ago, British physicist David Tyler notes that
All skeletalised metazoan phyla appeared in the Cambrian

Until this year, the Bryozoa were missing from the list of Cambrian organisms. Although some had been previously reported, critical scrutiny showed that they were misidentified and that the oldest known bryozoans came from Lower Ordovician strata. This year, however, Upper Cambrian bryozoans were reported from the lower Tinu Formation, southern Mexico. They were said to be about 8 Ma years older than the oldest Ordovician fossils. This means that Cambrian strata can be said to record examples of all the skeletalized metazoan phyla.
For more, go here.

The obvious lack of fit between the actual Cambrian event and the popular saga of the"long slow evolution of life" has sparked surprisingly little curiosity, compared to exercises in creative explanation of the "so-called" explosion, suppression of information, dunno-what-hit-us shock and reassurances about ongoing research. Too bad we can't just get past all that, to a genuine wish to know what happened.

Note: Illustration shows Bryozoan membranipora membranacea, US Geological Survey

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