Return to David's theory of evolution PART 1 The gap argumen (Evolution)

by David Turell , Sunday, June 12, 2022, 23:55 (893 days ago) @ David Turell

Ediacaran-Cambrian transition: 410,000 years

dhw: The gap between Ediacaran and Cambrian is irrelevant to our discussion of the “gaps” in the fossil record.

It is very relevant. Such a huge change in animal forms in such a short period doesn't fit the usual timing of a speciation change as in the whale series.

I'm sick of this twisting of the gap importance by dhw finding old comments about it.

The abstract of the article itself follows. The whole article is behind a paywall:

https://doi.org/10.1111/ter.12368

"The replacement of the late Precambrian Ediacaran biota by morphologically disparate animals at the beginning of the Phanerozoic was a key event in the history of life on Earth, the mechanisms and the time-scales of which are not entirely understood. A composite section in Namibia providing biostratigraphic and chemostratigraphic data bracketed by radiometric dating constrains the Ediacaran–Cambrian boundary to 538.6–538.8 Ma, more than 2 Ma younger than previously assumed. The U–Pb-CA-ID TIMS zircon ages demonstrate an ultrashort time frame for the LAD of the Ediacaran biota to the FAD of a complex, burrowing Phanerozoic biota represented by trace fossils to a 410 ka time window of 538.99 ± 0.21 Ma to 538.58 ± 0.19 Ma. The extremely short duration of the faunal transition from Ediacaran to Cambrian biota within less than 410 ka supports models of ecological cascades that followed the evolutionary breakthrough of increased mobility at the beginning of the Phanerozoic." (my bold)

"Faunal transition" means they studied the age of fossils on both sides of the gap.

("Last Appearance Datum ( LAD ): either local or global First Appearance Datum ( FAD ): either local or global Biozone (often just " zone "): Rock unit characterized by one or more taxa that permit it to be distinguished from adjacent rocks."

https://www.geol.umd.edu/~tholtz/G331/lectures/331biostrat1.html

Comment: this measurement of the gap is very significant, not irrelevant!!