May 11, 2010 | David F. Coppedge

More Pow in the Cambrian Explosion

Scientists have found more fossil evidence for sudden emergence of animal body plans in the Cambrian strata.  Two papers in Geology discuss evidence on opposite sides of the world.  One team found bryozoans in Mexico 8 million years older than the record-holders in China,1 and another scientist found diverse echinoderms in Spain dating from the middle Cambrian.2
    The author of the echinoderm paper, Samuel Zamora, said, “Because many of these taxa appear close to the beginning of the middle Cambrian, it seems likely that their origins must be placed in the early Cambrian.”2  He argued that his evidence militates against the slow-and-gradual appearance of echinoderms in the early Cambrian.  “This shows that, even by the earliest middle Cambrian, a variety of novel body plans and ecological strategies already existed among echinoderms, pushing back the timing of important divergences into the lower Cambrian.”  Not only that, the ones he found are among the “most diverse of anywhere.”  He did not use the word evolution nor comment on how these complex body plans could have emerged and diversified in such a short time.
    Bryozoans were thought to make their appearance on earth in the Ordovician.  Landing, English and Keppie reviewed the history of thinking about the Cambrian explosion, “Perhaps the most intensely dissected of these dramatic biotic diversity changes”.  They said that until recently, “One mineralized group, the phylum Bryozoa, seems to have ‘missed’ the Cambrian radiation.”  Their discoveries in Mexico now confirm “that all skeletalized metazoan phyla appeared in the Cambrian.”1  These authors also had little to say about how bryozoans emerged, other than to claim that they did – and now earlier than had been thought.  The discovery of these specimens in the late Cambrian does not preclude the possibility that bryozoans will some day be found in lower Cambrian strata elsewhere.

1.  Landing, English, and Keppie, “Cambrian origin of all skeletalized metazoan phyla�Discovery of Earth’s oldest bryozoans (Upper Cambrian, southern Mexico),” Geology, v. 38, no. 6, pp. 547-550; doi: 10.1130/G30870.1.
2.  Samuel Zamora, “Middle Cambrian echinoderms from north Spain show echinoderms diversified earlier in Gondwana,” Geology, v. 38 no. 6 p. 507-510; doi: 10.1130/G30657.1.

The trend of evidence has been clear for decades now.  Every major animal body plan is found in the Cambrian.  Each one is found earlier and earlier.  (Search on “Cambrian explosion” in our search bar for many other examples.)  The earliest ones are just as complex as later ones.  Where is the evolution?  Abrupt appearance of complex body plans is not evolution.  If you want to believe Darwin’s story of slow and gradual evolution, you believe it not because of the evidence, but in spite of it.
    Darwin’s theory is a fully naturalistic story – except for all the miracles needed to prop it up at every stage.  How did you like this little cryptically-stated miracle in the Landing et al paper: “specialized zooids appeared early in bryozoan phylogeny.”  Appeared.  Wonderful.  Tell us, How did they appear?  Enlightened rationalists want to know.  Did they just “emerge” out of the mud?  Did Tinker Bell zap an Ediacaran frond and a specialized bryozoan zooid popped out?  After watching Darwin’s Dilemma, we are getting a little weary of the mythological dogma repeated by the priests of the church of Darwin who say, “just believe.”

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Categories: Fossils, Marine Biology

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