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More Cambrian Woes for Evolution

Photo: Fossil bryozoans from the Upper Ordovician, by Wilson44691, CC BY-SA 3.0 , via Wikimedia Commons.

If new fossils were able to rescue Darwin from his Doubt and Dilemma, they would have turned up by now. Instead, they continue illustrating an alternate picture: abrupt appearance and intelligent design.

Et tu, Bryozoa?

Stephen Meyer can add another phylum to his chart of body plans in the Cambrian Explosion (Darwin’s Doubt, p. 32): phylum Bryozoa.

Bryozoans, earlier called Ectoprocta but now Bryozoa again, are small animals that live in colonies. The colonies resemble moss in texture, from whence the name Bryozoa, “moss animals.” Growing only to about 4 mm in size, the individuals (called zooids) bind together in tissue-like structures up to 3 feet in width. Zooids carry out differing functions to support the colony: filter feeding, defense, and reproduction. Some 5,000 species are known, inhabiting both fresh and salt water, and in tide pools all the way down to deep ocean trenches. Animal Fact Files has some video clips of living bryozoans on YouTube.

Bryozoa may look simple, but they are capable of sexual reproduction as well as hermaphroditism and budding. Despite their small size, they possess digestive systems and motile cilia. Long thought to have first appeared in the Ordovician (485 mya, the oldest fossils from China), bryozoans have now been confirmed in the early Cambrian. In Nature News and Views, Andrej Ernst and Mark A. Wilson write, “Bryozoan fossils found at last in deposits from the Cambrian period.” They had been “conspicuously absent” till now. Why so? Thinking Darwinly, Ernst and Wilson point out that “bryozoans have a complex form (morphology), and must therefore have already had a long evolutionary history.” Molecular studies had also suggested to evolutionists an earlier emergence.

That emergence is now confirmed at least 35 million years earlier in the evolutionary timescale, or 44 million years according to the molecular clock. Ernst and Wilson, announcing the lead paper in the same issue of Nature, make an audacious evolutionary claim:

Writing in Nature, Zhang et al. present a collection of fossils from early Cambrian deposits of China and Australia that are unequivocally bryozoans, and thus present evidence that solves one of the mysteries regarding the early diversification of animals. [Emphasis added.]

And Now the Hard Part

How can this solve the mystery of the early diversification of animals? Does adding independent suspects solve a murder mystery? The only reason they give is that the early Cambrian “ancestors” of bryozoans were soft-bodied, and most of the Ordovician species had hard parts: 

Zhang and colleagues’ study shows that bryozoan evolution had a notable, previously hidden history in the early Cambrian. Although this was assumed by many researchers, only now is there reliable evidence for it. The absence of hard skeletal parts in P. gatehousei explains why bryozoans were previously missing from the fossil record of the Cambrian…. 

Now that this ancestral mystery has been solved, attention can move to filling in the story of bryozoan evolution from the early Cambrian to the early Ordovician.

Hard parts might explain the preservation of bryozoans, but not their origination. Surely the latter question is the real “hard part” of the story. Meyer’s primary question echoes through the eight years since his book came out: what was the source of the information for the complex body plan in this and the twenty or so other animal phyla that exploded onto the scene in the early Cambrian? 

These Cambrian bryozoans were not exactly simple. Except for skeletal parts, they look remarkably similar to Ordovician species. They possessed a holdfast, “suggesting an erect, self-supported colony anchored to the substrate.” Nor does the new species qualify as a common ancestor of bryozoans, because it already contained features of other families. Indeed, “the last common ancestor of total-group Bryozoa remains enigmatic,” the authors confess.

The photos of the fossil specimens and the following description reveal that this was another complex body plan, unrelated to other phyla, that appeared suddenly in the early Cambrian.

The honeycomb-like network of zooids in P. gatehousei [the new fossil] demonstrates that hierarchical architecture and complexity of colonial life was also an important evolutionary innovation during the Cambrian radiation of animal life.

Innovation is a euphemism for abrupt appearance without an intelligent cause. This quote speaks for itself:

The interpretation of this secondarily phosphatized fossil from lower Cambrian rocks of South China and South Australia as a putative bryozoan indicates that modular bryozoans evolved synchronously with most other stem-group metazoans during the Cambrian evolutionary radiation.

A correction is in order: it was not a “Cambrian evolutionary radiation.” It was a “Cambrian explosion” of fully functioning animals with hierarchical body plans that defies evolution. The only cause able to account for hierarchical functioning systems is intelligence.

Ordovician Impact

Speaking of the Ordovician, it exploded too. The “Ordovician radiation” saw a rapid diversification of bryozoans and everything else under the sea. News from the University of Copehagen explains:

In a geological period 469 million years ago known as the Ordovicium [sic] Period, Earth’s seas were inhabited by animals like trilobites (reminiscent of pillbugs), conodonts (eel-like vertebrates) and brachiopods (animals with two-part shells reminiscent of seashells).

But suddenly, something happened that became crucial for life to develop towards the life we know from today’s oceans. Marine biodiversity quadrupled in a few million years. In fact, it was the largest increase in biodiversity in the history of our planet.

Now for the punch line: it was an asteroid that exploded. Or, maybe it wasn’t. Previously, evolutionists thought that this “greatest increase in marine biodiversity on Earth was not due to the explosion of an asteroid,” but the experts in Copenhagen know better now. It was climate change.

“Instead of triggering an increase in biodiversity, the cosmic dust from the asteroid’s explosion probably acted as a temporary brake on species evolution. The dust blocked sunlight, which impaired most photosynthetic processes — and the living conditions of animals in general, as a result,” explains Jan Audun Rasmussen, curator and researcher at Museum Mors and the study’s lead author.

These evolutionists are not denying the asteroid explosion; they are just removing it as a cause for the Ordovician radiation. It did the opposite, they say; it slowed down “species evolution.” Too bad; the evolutionists probably cannot now conjure up an asteroid to explain the Cambrian Explosion. 

The new story is that Milankovitch cycles cooled the planet, and the global cooling caused the explosion in diversity. That explanation is given in Nature Communications by Rasmussen et al., “Middle Ordovician astrochronology decouples asteroid breakup from glacially-induced biotic radiations.” Hey; climate change is trending these days. Why not try that on the Cambrian Explosion? Add some heat; take away some heat; who knows what climate change might do for evolution?

Sponge Nerves

The power of suggestion has mesmerized Max Koslov and his experts at Nature: they imagine “nervous system precursors” in sponges.

On the basis of the proximity of the two cell types and the expression of genes that might allow for the secretion of chemicals, the researchers think that these arms enable neuroids to communicate with choanocytes, so that they can pause the water-flow system and clear out any debris or foreign microbes. However, these neuroid cells are not nerves, and there is no sign of the synapses that enable neurons to communicate so quickly. Instead, this cell type might represent an evolutionary precursor to a true nervous system, says Jacob Musser, an evolutionary biologist at EMBL, who co-authored the study. “We’re at an intermediate point, where you’ve gone from having all these independent pieces to bringing them together more broadly, but you haven’t gotten all the interconnectivity needed to create a fast synapse,” he says.

Undoubtedly sponges are successful animals since they are still with us today. But even other evolutionists are putting the squeeze on the notion.

Some scientists say that calling these cells a precursor to a nervous system is a stretch. “It’s tantalizing, but it’s hardly definitive,” says Linda Holland, an evolutionary developmental biologist at the University of California, San Diego. She says it will be difficult to prove whether nervous systems evolved from this cellular communication system or arose earlier or even multiple times, as some groups have proposed. Indeed, many other organisms, including unicellular eukaryotes, contain the same synaptic genes, says Sally Leys, a marine biologist at the University of Alberta in Edmonton, Canada.

Meanwhile, the Cambrian Explosion remains mysterious to those who deny intelligent design. Evolution marches on. Maybe the reward is the process, not the proof.