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Fossil Friday: Update on Cambrian Bryozoans

Photo credit: Killamator, CC BY-SA 4.0 , via Wikimedia Commons.

A few weeks ago, I commented (Bechly 2023) on the abrupt origin of Bryozoa either during the Cambrian Explosion or in the Great Ordovician Biodiversification Event, both of which have been called big bangs of life by mainstream evolutionary biologists. I especially emphasized the back and forth concerning the interpretation of putative bryozoan fossil from the Cambrian period. I mentioned that a new study by Yang et al. (2023a) had recently challenged the bryozoan status of the genus Protomelission from Cambrian limestone in Australia, and instead identified it as a dasyclad green algae.

Now, a new study (Yang et al. 2023b) has been uploaded to the preprint archive bioRxiv. (The lead author only coincidentally shares the same name as that of the lead author of the earlier study.) This new study strongly rejects the determination as dasyclad green algae in favor of an identification as archaeocyath-like sponges, based on the analysis of multiple specimens that show the typical skeletal structures, aquiferous system, and ontogeny. Archaeocyaths, which are “broadly accepted as an extinct class of the phylum Porifera, were the earliest reef-building metazoans in the Phanerozoic” and “reached a biodiversity of over 300 genera and ca. 1500 species before the end of the Cambrian Age 4” (Yang et al. 2023b).

The authors emphasize that “the origin of the bryozoans remains a mystery” but explicitly confirm the reality of the Cambrian Explosion as “the most significant evolutionary event in Earth history in terms of setting up stem- and even crown-groups of almost all major metazoan phyla.” That’s bad news for the science deniers among the hardcore Darwinists and anti-ID activists, who recently have tended more and more simply to deny the Cambrian Explosion as a real event, and instead claim it to be just an artifact of an incomplete fossil record or even a straw man set up by evil creationists. The real experts disagree and fully corroborate the thrust of Stephen Meyer’s point in his book Darwin’s Doubt.