Thursday, 5 September 2019

Evolution News - Cambrian 'Explosion' Blows up in Creationists' Face

Yilingia spiciformis and the track it left as it moved.
Credit: Z. Chen et al./Nature
Ancient worm fossil rolls back origins of animal life.

It's another of those bad days for creationism, like most days in biology research, in fact.

This time, one of their favourite misrepresentations - the so-called Cambrian Explosion - just got a lot harder to misrepresent. Fossil evidence has been found of a much earlier complex multicellular, worm-like organism.

This gives the lie to any claims that the Cambrian biota appeared suddenly without ancestry, as though some celestial designer arrived on Earth one day and plonked a whole lot of different, fully formed species, in the sea.

The so-called Cambrian Explosion was nothing of the sort, of course. It took some 20 million years to happen, during which the soft-bodied organisms (hard endo- and exo-skeletons had yet to evolve) were only captured and fossilised in very rare and unusual conditions such as the formation of the Burgess Shale. The 'sudden' appearance of the Cambrian biota is thus easily explained by the discontinuity and paucity of the fossil record.

Y. spiciformis showing a distinct front and back end, tapering towards the rear.
Credit: Z. Chen et al./Nature
However, that point is too subtle for creationists eager to be duped to comprehend, so the creation industry, led by the Discovery Institute, has managed to bamboozle their scientifically illiterate and credulous dupes into believing that it really was a single event, with no explanation possible from conventional 'Darwinian' evolution.

Now we have definitive evidence of ancestry already evolved during the Ediacaran period, when it had been thought that the first multicellular organisms' bodies had not been strongly differentiated into specialised structures, so they tended to be sendentery. Indeed, one theory for the success of the Cambrian biota and for the sudden disappearance of the Ediacaran biota was that the Cambrian animals simply ate all the Ediacarans which had evolved in the absence of predators, so had no defences.

It is just pushing things further and further back into the Ediacaran. The Cambrian explosion no longer appears to be such an abrupt event in the history of life on Earth

Rachel Wood
Geoscientist at the University of Edinburgh, UK.
The new fossil is of a worm-like creature having a distinct front and rear end, which was mobile and able to crawl over the ocean floor, leaving characteristic tracks. This particular fossil is the body of one such organism, named Yilingia spiciformis at the end of a track. It has been dated to the Ediacaran period between 551 million and 539 million years ago.

The team who discovered it have published their findings in Nature, but all except the Abstract is paywalled, which is a annoying to say the least, especially since there are some beautifully detailed photographs of the fossils, showing a distinct trilobate structure, giving Y. spiciformis the appearance of a highly elongated trilobite.

So, here is clear evidence that differentiated, complex, mobile organisms were already in existence before the Cambrian period, providing possible ancestors for the Cambrian biota.

The creationist claim that a magic designer poofed the Cambrian biota into existence without ancestors is thus untenable, even if anyone had ever managed to explain how such a designer could have spontaneously self-generated from nothing and even if someone had ever managed to come up with an explanation for how this putative designer creates things from nothing.

Biologically, what is interesting about Y. spiciformis is that it appears to have paired appendages which could be legs. If so, it could be a primitive ancestor of the arthropods such as insects, spiders and crustaceans. However, these 'legs' could be an artifact of the fossilisation process, in which case Y. spiciformis may be an ancestral segmented (annelid) worm, which itself could be a common ancestor of both the annelid worms and of the arthropods.

All in all, another bad day for creationism, when one of its favourite sources of disinformation has blown up in it's face and a good day for biology. Another gap has been closed by evidence which once again confirms evolution and refutes creationism without even trying.







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1 comment :

  1. More images at https://irawe.com/death-march-of-a-segmented-and-trilobate-bilaterian-elucidates-early-animal-evolution/

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