In a recent series of Evolution News articles (Bechly 2018b, 2019, 2020a, 2020b, 2020c), to be continued soon, I have presented evidence and arguments that refute several alleged fossil animals from the Ediacaran period, which had been proposed as potential precursors of Cambrian animal phyla. Of course, the general absence of fossil bilaterian animals from the Ediacaran era is hardly a secret among paleontologists, but certainly an inconvenient truth, because it leaves the appearance of complex animal phyla during the Cambrian explosion disturbingly unexplained.
It also contradicts Darwinian expectations of a gradual development of complex body plans from the bottom up, starting with simple unicellular organisms and the subsequent stepwise addition of many small changes. Where are the proposed thousands of intermediate forms that led to Cambrian animals like trilobites? Evolutionists were dumbfounded by the silence in the fossil record and had to come up with a ready explanation for this conflicting evidence. The most popular attempt to resolve this discrepancy is the so-called “artifact hypothesis,” which proposes that the Cambrian animal phyla had ancestors, but that those ancestors either left no fossil record or have not yet been found (Meyer et al. 2007: 144), because of the incompleteness of the fossil record. This ad hoc hypothesis was originally proposed by Charles Walcott, the discoverer of the famous Burges Shale fossils. More recently it was for example championed by paleontologist Donald Prothero in his critical review of Stephen C. Meyer’s book Darwin’s Doubt (Prothero 2013).
The Artifact Hypothesis
In his seminal work Darwin’s Doubt, Stephen Meyer (2013) had thoroughly discussed the artifact hypothesis and dismissed it based on the available scientific evidence. As a paleontologist, I can hardly agree more with this conclusion. My only point of difference would be that I would no longer consider the phosphatized “embryo-like” fossils of the Wen’an Biota from the Doushantuo Formation in China as best argument, because of their highly controversial and very dubious attribution (Bechly 2020c). Nevertheless, the fact that most specialists reject any affinity of these fossils with crown-group animals (Zhang et al. 1998, Xue et al. 1999, Hagadorn et al. 2006, Bailey et al. 2007, Huldtgren et al. 2011, 2012, Butterfield 2011, Kaplan 2011, Bengtson et al. 2012, Chen et al. 2014, Cunningham et al. 2017) strongly suggests that there is no convincing evidence for any animals from this 560-million-year-old locality.
Of course, the argument from the Doushantou fossils is somewhat weak, because it is a very specific type of fossilization that implies taphonomic filters to what can be preserved and what not. But we meanwhile have much better evidence against the artifact hypothesis. According to Gaines et al. (2012), “Burgess Shale−type biotas occur globally in the Cambrian record and offer unparalleled insight into the Cambrian explosion, the initial Phanerozoic radiation of the Metazoa. Deposits bearing exceptionally preserved soft-bodied fossils are unusually common in Cambrian strata; more than 40 are now known.” Thus, we definitely should expect to find the postulated ancestors of the Cambrian animal phyla in Burgess Shale-type localities of the preceding Ediacaran era. The artifact hypothesis suggested that there are no such localities. However, in the past years several fossiliferous Burgess Shale-type (BST) biota from the Ediacaran have been discovered:
- Pusa Shale of Spain (Brasier et al. 1979, Jensen & Palacios 2016)
- Chopoghlu Shale / Soltanieh Formation of northern Iran (Ford & Breed 1972)
- Khatyspyt Formation of Siberia (Grazhdankin et al. 2008)
- Miaohe biota of southern China (Xiao et al. 2002, Tang et al. 2008, Ye et al. 2017)
- Lantian biota of southern China (Yuan et al. 2011, 2013)
- Jinxian biota of northern China (Luo et al. 2016)
- Zuun-Arts biota of western Mongolia (Dornbos et al. 2016, Hassell et al. 2017)
None of these Ediacaran biotas yielded any uncontroversial fossil record of animals! Especially important are the vast deposits of the Miaohe and Lantian biotas in China and the Zuun-arts biota in Mongolia, which both lack any bilaterian animals and only yielded fossil algae and problematic organisms. A proposed cnidarian affinity of some Lantian fossils (Van Iten et al. 2013, Wan et al. 2016) remains equivocal (Bowyer et al. 2017) and they could rather represent macroalgae as well (Yuan et al. 2011). Even the most recent study by Daley et al. (2018), which very unsuccessfully (Bechly 2018a) tried to downplay the abruptness of the Cambrian explosion, acknowledged that these new localities have proven that fossil animals are not just unknown from the Ediacaran because of preservation issues but because they definitely did not yet exist. Daley et al. discussed all the above-mentioned Burgess Shale-type localities from the Ediacaran and concluded that the “modes of fossil preservation are comparable in the Cambrian and Precambrian.” In their abstract they affirmed that: “BSTs from the latest Ediacaran Period (e.g., Miaohe biota, 550 Ma) are abundantly fossiliferous with algae but completely lack animals, which are also missing from other Ediacaran windows, such as phosphate deposits (e.g., Doushantuo, 560 Ma).”
From the Royal Society
Now, a new study by Anderson et al. (2020), published in a Royal Society journal, analyzed microfossils from a 1-billion-year-old and two 800-million-year-old localities in Russia, Svalbard, and Canada, which also belong to the Burgess Shale type and thus could preserve early soft-bodied animals. The authors conclude in their abstract: “These deposits lack metazoan fossils even though they share fossilization conditions with younger BST deposits that are capable of preserving non-mineralizing metazoans. Thus metazoans, at least those typically preserved in BST deposits, were probably absent from sedimentary environments before approximately 800 Ma.” Here is what Demming (2020) commented about this new study: “The results suggest the same processes preserved pre-Cambrian microbes as later larger animals. ‘So the fact that there are no animals in the 800-million-year-old rocks, even though they’ve got the same type of preservation — all you find there are bacteria or the algae analyzed — that would suggest that animals really haven’t evolved at that time,’ says Anderson.”
So, demonstrably no animal biota existed 1 billion, 800 million, 560 million, and even 550 million years ago (the only remotely plausible candidates are the late Ediacaran jellyfish Haootia, the mollusk-like Kimberella, the worm-like Yilingia, and the possible lophophorate Namacalathus, which I will discuss in future articles). But in the lowermost Cambrian, 537 million years ago, there were already complex arthropod body plans with exoskeleton, articulated legs, and compound eyes (Daley et al. 2018), as well as many other bilaterian animal phyla. To deny that this is a major problem for Darwinian evolution is absurd.
Finally Put to Rest
We can conclude that the artifact hypothesis, which was nothing but an ad hoc strategy to get rid of conflicting evidence, can finally be put to rest for good. The absence of Ediacaran fossils of putative precursors of the Cambrian animal phyla is not an artifact of undersampling or an artifact of taphonomy, but simply reflecting the fact that there were no such organisms living in this period. With increasing paleontological research and better knowledge of the Proterozoic fossil record, the Cambrian explosion has turned out to be even more abrupt than was previously thought (Bechly 2018a). If a problem does not dissolve with increasing knowledge but only gets worse over time, it is a good indicator that this problem is very real. Darwinists have to face the fact that a core prediction of their theory miserably failed an important empirical test. Intelligent design theory much better agrees with the empirical evidence and can elegantly explain the abrupt origins we find throughout the fossil record.
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Image: The “Garden” of Ediacara, via Wikimedia.