The Cambrian Explosion, as excavated in Yunnan, China, is in the news again:
The 518-million-year-old Chengjiang Biota—in Yunnan, south-west China—is one of the oldest groups of animal fossils currently known to science, and a key record of the Cambrian Explosion.
Fossils of more than 250 species have been found there, including various worms, arthropods (ancestors of living shrimps, insects, spiders, scorpions) and even the earliest vertebrates (ancestors of fish, amphibians, reptiles, birds and mammals).
The new study finds for the first time that this environment was a shallow-marine, nutrient-rich delta affected by storm-floods…
“The Cambrian Explosion is now universally accepted as a genuine rapid evolutionary event, but the causal factors for this event have been long debated, with hypotheses on environmental, genetic, or ecological triggers,” said senior author Dr. Xiaoya Ma, a palaeobiologist at the University of Exeter and Yunnan University.
University of Exeter, “Modern animal life could have origins in delta” at Phys.org (March 23, 2022)
“now universally accepted as a genuine rapid evolutionary event”? So we’re past trying to pretend that it was in reality much slower? Okay…
Now, about the shallow, vs. deep, water:
The results of this study are important because they show that most early animals tolerated stressful conditions, such as salinity (salt) fluctuations, and high amounts of sediment deposition.
This contrasts with earlier research suggesting that similar animals colonized deeper-water, more stable marine environments.
“It is hard to believe that these animals were able to cope with such a stressful environmental setting,” said M. Gabriela Mángano, a palaeontologist at the University of Saskatchewan, who has studied other well-known sites of exceptional preservation in Canada, Morocco, and Greenland.
University of Exeter, “Modern animal life could have origins in delta” at Phys.org (March 23, 2022)
So these animals not only got started in a short period of time but were sophisticated enough to tolerate a stressful environment? The Cambrian gets more remarkable every time we dig into it.
The paper is open access.
You may also wish to read: Can the Cambrian Explosion be explained away by the earlier Ediacaran Explosion? David Klinghoffer: “Lukas Ruegger is the personable new intelligent design “explainer” whose videos take an approach similar to Khan Academy’s. The latter’s offering on evolution is replete with junk science, as Casey Luskin has detailed. Ruegger’s treatment of the subject is much better, and I appreciate his clarity and brevity.”