Paleontologist Gunter Bechly looks at the claim that the Cambrian animals evolved from a long train of Ediacaran ancestors who somehow all just disappeared without a trace and finds it, well, unconvincing:
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).
Günter Bechly, “The Demise of the Artifact Hypothesis” at Evolution News and Science Today:
The “artifact” in this case is Darwinism itself.