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Fossil Friday: The Avalon Explosion and the Power of Maybe

October 11, 2024, 6:35 AM
Photo credit: Verisimilus at English Wikipedia, CC BY-SA 3.0 , via Wikimedia Commons.

This Fossil Friday features the 569-556-million-year-old frond-like fossil Charnia from Charnwood Forest in Leicestershire (UK), an example of the abrupt appearance of the so-called Ediacaran biota in the latest Precambrian. During this event, which has been called the Avalon Explosion (see Bechly 2024) and preceded the famous Cambrian Explosion, we find in three distinct assemblages the emergence of strange organisms that looked like aliens from a remote planet. They were very much unlike any of the organisms that roamed our planet after the Cambrian Explosion and certainly did not represent the ancestors of the Cambrian bilaterian animal phyla. The Ediacaran organisms generally exhibited a quilted body like an air mattress, a glide symmetry, a fractal growth pattern, and lacked any visible organs for feeding or locomotion or any internal structure. A genuine enigma for biologists and paleontologists.

A New Study

In a brand new study by Bowyer et al. (2024), three distinguished scientists from the University of Edinburgh analyzed the geological evidence for sea level changes (mainly changes in sedimentary rock volume as proxy), and compared them with the reconstructed biodiversity in terms of genus richness during different phases of the Ediacaran period, correlated according to a global age framework of high-precision radiometric datings. They found that “each successive rise of metazoan morphogroups that define the Avalon, White Sea, and Cambrian assemblages appears to coincide with global shallow marine oxygenation events at δ13Ccarb maxima, which precede major sea level transgressions” and concluded that “while the record of biodiversity is biased, early metazoan radiations and oxygenation events are linked to major sea level cycles.”

Well, that is certainly interesting, even though one should never forget that correlation does not imply causation. Therefore, the authors are to the point when they open their abstract with the admission that “the drivers of Ediacaran-Cambrian metazoan radiations remain unclear.” The press release for the study was much less prudent, with the pompous title “Sea level changes shaped early life on Earth, fossils show” (University of Edinburgh 2024). It quotes one of the authors with this statement: “Knowing what drives biodiversity is a fundamental piece of knowledge in the puzzle of life. I feel very privileged to have built upon decades of interdisciplinary global research, and contributed to a better understanding of the role that sea level plays in early animal evolution.” Did they?

Maybe, Possibly, It Might Be

Have you noticed the little qualifier “appears” in the first quote above? Here is something to think about: This supposedly very scientific article contains not fewer than 64 (!) times the words “may” or “might”, 20 times the word “possible,” 11 times the word “potential(ly),” 8 times the word “likely,” and 7 times the word “appears.” So, we are left with the take home message that this study maybe could possibly appear to potentially show that there might be some likely connection between sea level changes and biodiversity changes. However, even if this should indeed be the case, how did those sea level changes magically produce the new genetic information for the emergence of organisms with new body plans? Crickets — the article does not even mention the words “genetics’ or “genes” a single time.

Instead the authors simply suggest that “major transgressions would therefore both increase habitable shallow marine shelf area and also drive long-term increases in environmental oxygen levels, which culminated in the appearance of the Avalon, White Sea, and Cambrian assemblages.” As I have often said, these are at best describing necessary conditions for the appearance of new organisms but certainly not sufficient conditions. There is zero causal explanation for the astonishing culmination in the appearance of the totally new types of organisms that characterize these assemblages. The new study was published in the prestigious journal Science Advances, but did it really advance our understanding of the mechanisms responsible for the sudden origin of the Ediacaran biota? The answer must be a resounding no, not even a single bit. While evolutionary biology has no explanation even according to the authors themselves, intelligent design theory does uniquely provide a causally adequate explanation and therefore should be preferred over the blind acceptance of Darwinian magic as an imposed default explanation.

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