According to Wikipedia’s article on the so-called Cambrian explosion:
The Cambrian explosion or Cambrian radiation was an event approximately 541 million years ago in the Cambrian period when most major animal phyla appeared in the fossil record. It lasted for about 20–25 million years. It resulted in the divergence of most modern metazoan phyla. The event was accompanied by major diversification of other organisms.
But according to the Discoveroids, the Cambrian explosion was a magic moment when their intelligent designer — blessed be he! — came to Earth and whomped up a whole bunch of new species. So who’s right?
To help you make up your mind, some new research is reported at PhysOrg. Their headline is Major fossil study sheds new light on emergence of early animal life 540 million years ago. Here are some excerpts, with bold font added by us for emphasis:
All the major groups of animals appear in the fossil record for the first time around 540-500 million years ago — an event known as the Cambrian Explosion — but new research from the University of Oxford in collaboration with the University of Lausanne suggests that for most animals this ‘explosion’ was in fact a more gradual process.
Egad — a gradual process? Then PhysOrg says:
The Cambrian Explosion produced the largest and most diverse grouping of animals the Earth has ever seen: the euarthropods. Euarthropoda contains the insects, crustaceans, spiders, trilobites, and a huge diversity of other animal forms alive and extinct. They comprise over 80 percent of all animal species on the planet and are key components of all of Earth’s ecosystems, making them the most important group since the dawn of animals over 500 million years ago.
A team based at Oxford University Museum of Natural History and the University of Lausanne carried out the most comprehensive analysis ever made of early fossil euarthropods from every different possible type of fossil preservation. In an article published today in the Proceedings of the National Academy of Sciences they show that, taken together, the total fossil record shows a gradual radiation of euarthropods during the early Cambrian, 540-500 million years ago.
Here’s the paper they’re talking about: Early fossil record of Euarthropoda and the Cambrian Explosion. Without a subscription, you can only see the abstract. PhysOrg tells us:
The new analysis presents a challenge to the two major competing hypotheses about early animal evolution. The first of these suggests a slow, gradual evolution of euarthropods starting 650-600 million years ago, which had been consistent with earlier molecular dating estimates of their origin. The other hypothesis claims the nearly instantaneous appearance of euarthropods 540 million years ago because of highly elevated rates of evolution.
The new research suggests a middle-ground between these two hypotheses, with the origin of euarthropods no earlier than 550 million years ago, corresponding with more recent molecular dating estimates, and with the subsequent diversification taking place over the next 40 million years.
Forty million years? We’d expect better from the intelligent designer. To make it even worse for the Discoveroids, they quote Professor Allison Daley, the lead author of the paper:
“This indicates that the Cambrian Explosion, rather than being a sudden event, unfolded gradually over the ~40 million years of the lower to middle Cambrian.”
One last excerpt from PhysOrg:
Harriet Drage, a Ph.D. student at Oxford University Department of Zoology and one of the paper’s co-authors, says: “When it comes to understanding the early history of life the best source of evidence that we have is the fossil record, which is compelling and very complete around the early to middle Cambrian. It speaks volumes about the origin of euarthropods during an interval of time when fossil preservation was the best it has ever been.”
One question remains: How will the Discoveroids react to this? They can’t ignore it. It’ll be fun to see their reaction.
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