The missing fossils argument (Introduction)

by David Turell @, Thursday, January 20, 2022, 15:10 (129 days ago)

Trying to explain gaps in the fossil record by hoping missing fossils will be found is a losing cause with new studies of th e Edicaran and Cambrian gap:

https://reasons.org/explore/blogs/todays-new-reason-to-believe/cambrian-explosion-becom...

"The new phyla that appeared in the Cambrian explosion (a largely marine event) included the first animals to possess skeletons, digestive tracts, circulatory systems, and complex internal and external organs. Not until the Cambrian explosion was there sufficient oxygen in Earth’s atmosphere and oceans for such animals to exist.

"Animals that suddenly appeared at the beginning of the Cambrian period included the most advanced phyla in Earth’s history. We humans belong to the chordate phylum, which is characterized by animals that possess a dorsal hollow nerve cord and a notochord. All vertebrates and many invertebrates belong to the chordate phylum. Paleontologists have discovered fossils of chordates, including some vertebrates, that date back to the very beginning of the Cambrian period.

***

"Two of the best attempts to determine an absolute date for the Cambrian explosion were undertaken by research teams led by Diazhao Chen and Can Chen, respectively. Diazhao Chen and four colleagues obtained uranium-lead zircon ages from the Ediacaran-Cambrian boundary strata, where one stratum contains fossils of Ediacaran (the period prior to the Cambrian) animals and the immediately adjacent stratum contains fossils of Cambrian animals in the Liuchapo Formation in South China.

"The fossil record reveals that the Ediacaran animals were the first to appear on Earth. Unlike the Cambrian animals, the Ediacaran fauna lacked digestive tracts, circulatory systems, skeletons, and complex organs. The record shows that the Ediacaran fauna experienced a sudden worldwide mass extinction event that was quickly followed by the appearance of the Cambrian explosion animals.

***

"They found a composite geological section in southern Namibia of the Ediacaran-Cambrian boundary that provided biostratigraphic and chemostratigraphic data that was bracketed by radiometric dating. Their measurements constrained the date for the Ediacaran-Cambrian boundary to no earlier than 538.99 ± 0.21 million years ago and no later than 538.58 ± 0.19 million years ago. Therefore, they concluded that the faunal transition from Ediacaran to Cambrian biota occurred within less than 410,000 years.

***

"A time window for the Cambrian explosion briefer than 410,000 years is far too brief for any conceivable naturalistic model for the history of life. It would be far too brief even for the appearance of just one new phylum, let alone 30+ phyla. These discoveries make paleontologist Kevin Peterson’s conclusion in his review paper on the Cambrian explosion—published a dozen years ago—all the more compelling: “Elucidating the materialistic basis for the Cambrian explosion has become more elusive, not less, the more we know about the event itself.”8 The same goes for Gregory Wray’s review published in 1992, “The Cambrian ‘explosion’ of body plans is perhaps the single most striking feature of the metazoan fossil record. The rapidity with which phyla and classes appeared during the early Paleozoic coupled with much lower rates of appearance of higher taxa since, poses an outstanding problem for macroevolution.” (my bold)

Comment: I've quoted Bechly in the past: " "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, because of the incompleteness of the fossil record." Now more Bechly: "Recently, I stumbled upon a paper from 2018 that I had previously overlooked, and it proved to be dynamite. It is a study by a research group from the University of Zurich about the transition from the Ediacaran organisms to the Cambrian animal phyla in the Nama Basin of Namibia (Linnemann et al. 2018). What they found is truly mind-blowing. The window of time between the latest appearance date (LAD) of the alien Ediacaran biota and the first appearance date (FAD) of the complex Cambrian biota was only 410,000 years. You read that correctly, just 410 thousand years! This is not an educated guess but based on very precise radiometric U-Pb dating with an error margin of only plus-minus 200 thousand years. This precision is truly a remarkable achievement of modern science considering that we are talking about events 538 million years ago.

So I might add, without fossils, imagining lost fossils disappears. I've left out two supporting study descriptions. The findings are solid.

The missing fossils argument

by David Turell @, Tuesday, May 17, 2022, 21:02 (11 days ago) @ David Turell

New findings in the pre-Cambrian gap period:

https://phys.org/news/2022-05-animals-complex-ecosystems-cambrian-explosion.html

"Early animals formed complex ecological communities more than 550 million years ago, setting the evolutionary stage for the Cambrian explosion, according to a study by Rebecca Eden, Emily Mitchell, and colleagues at the University of Cambridge, UK, publishing May 17th in the open-access journal PLOS Biology.

"The first animals evolved towards the end of the Ediacaran period, around 580 million years ago. However, the fossil record shows that after an initial boom, diversity declined in the run-up to the dramatic burgeoning of biodiversity in the so-called "Cambrian explosion" nearly 40 million years later. Scientists have suggested this drop in diversity is evidence of a mass extinction event roughly 550 million years ago—possibly caused by an environmental catastrophe—but previous research has not investigated the structure of these ancient ecological communities.

"To evaluate the evidence for an Ediacaran mass extinction, researchers analyzed the metacommunity structure of three fossil assemblages that span the last 32 million years of this geological period (between 575 to 543 million years ago). They used published paleoenvironmental data, such as ocean depth and rock characteristics, to look for metacommunity structure indicative of environmental specialization and interactions between species. The analysis revealed increasingly complex community structure in the later fossil assemblages, suggesting that species were becoming more specialized and engaging in more inter-species interactions towards the end of the Ediacaran era, a trend often seen during ecological succession.

"The results point to competitive exclusion, rather than mass extinction, as the cause of the diversity drop in the late Ediacaran period, the authors say. The analysis indicates that the features of ecological and evolutionary dynamics commonly associated with the Cambrian explosion—such as specialization and niche contraction—were established by the first animal communities in the late Ediacaran.

"Mitchell adds, "We found that the factors behind that explosion, namely community complexity and niche adaptation, actually started during the Ediacaran, much earlier than previously thought. The Ediacaran was the fuse that lit the Cambrian explosion.'"

Comment: I have seen the picture of this period in the Edicaran period. They are a variety of frond-like plant-looking, but are thought to be animals. You must download the article to see it:

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001289


No complexity like in the Cambrian animals. The phenotypic gap persists, and this article is another Darwinian attempt to shrink the gap.

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