Sensational Non-explosive fossil

One of the arguments used by creationists is that evolution cannot explain the so-called "Cambrian Explosion". In fact it has been known for some years that the evidence actually points to the "Cambrian Explosion" being more an artefact of the fossil record.To sum up the relevant points :1) The known species from the Cambrian still fit well into the nested hierarchy expected from evolution2) Molecular evidence points to phyla diverging well before the "Explosion"3) A few trace fossils, and a few fossilised embryos of primitive metazoans discovered in China provided fuirther support.
(this page Palaeos: Page not found provides some information)4) There are reasons why the known fossil record might not record the species existing prior to the "Explosion". It is well-known that soft-bodied creatures are rarely fossilised, but it is also the case that small animals are rarely fossilised. In both cases there are rare circumstances that can produce fossils (such as the embryos mentioned above).Now a new fossil has provided yet more evidence. Although the fossil is tiny, it is of an adult and so presents our best insight into the primitive life that predated the "Explosion" - and provides yet more evidence that the "Explosion" is largely due to the limits of the fossil record. It is a dramatic confirming evidence for the picture that paleontology has been putting together of the prelude to the "Explosion" - which turns out to be much less of an explosion than was once thought.Here is the article:
Pharyngula - Hotell anbefalinger Barcelona

Thread moved here from the Proposed New Topics forum.

Boy, those "gaps" keep getting smaller all the time, eh?

It's interesting to see how quickly the news of these finds spread these days. Just a quick look on the web showed writups from sites in English speaking countries, China, Japan, Germany, Italy and France. Amazing compared to the days of Beagle.

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Aslan is not a Tame Lion

So what? Look how many more there are!!

I never really understood why a rapid speciation was perceived, by creationists, to be impossible (Esp. since some of them try to claim rapid speciation of "kinds" over 5000 years). After all, if a new trait opens up multiple new niches without competition, we should expect a rapid increase in populations and thus more individuals that can mutate and fit into even more untapped niches. That process really shouldn't slow down until we start running out of niches?(And, of course, the KE really isn't that impressive an "explosion" nyway when, as mentioned, it is a rather large timespan and also seems to stretch beyond this timespan anyway. The speciation rate really isn't that significant.

There's some more information here. The most impressive thing is the sheer work required to find these fossils. And there are more pictures - well worth a look.Pharyngula - Hotell anbefalinger Barcelona

PaulK, I've become a bit dubious about this claim. As far as I'm aware molecular clocks are calibrated by the fossil record. It stands to reason, therefore, that any proposed divergence must predate the earliest instance of any two taxa making point 2) a non-point.Are molecular clocks calibrated by any other method than by looking at the fossil record?Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Hello, mark24.I think the significance of the "molecular clock" data is that the major phyla did not diverge "just before" the Cambrian explosion. Of course the major phyla separated before we see fossil evidence of this -- this significance of the molecular data is that this divergence occurred long, long before the Cambrian.My amature, barely-literate impression of this sort of data is that there are problems with the calibration of the molecular clock. However, I get the impression that no matter what reasonable correction we make, the major phyla diverged long before the Cambrian, even if we can't be sure of the exact timing.

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I never really understood why a rapid speciation was perceived, by creationists, to be impossible (Esp. since some of them try to claim rapid speciation of "kinds" over 5000 years). After all, if a new trait opens up multiple new niches without competition, we should expect a rapid increase in populations and thus more individuals that can mutate and fit into even more untapped niches. That process really shouldn't slow down until we start running out of niches?

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We have examples of rapid speciation, such as mice and rats being introduced to an island. What we see at the genetic level is numerous species that are highly related at the genetic level. If the creationist theory is true, then we should see this same relatedness among (the yet to be defined) kinds. What we find is that there is much more genetic dissimilarity among the kinds than would be expected in 2,000 years of speciation. Of course, the other problem is that creationists are very careful never to define what the kinds are so that they aren't painted into a corner.

Chiroptera, Gotcha.Mark

My understanding, though, is that the "Cambrian Explosion" may still be real event (with the caveats expressed in the OP) in that this may mark the time when the phyla underwent dramatic modifications. It is possible that the representatives of each of the phyla were simply separate lineages of barely undistinguishable (to my untrained eye, anyway) worms, and then near the beginning of the Cambrian (perhaps responding to a mass extinction of the Ediacaran fauna) underwent "rapid" evolution to more or less the forms we see.Edited to add:
God, this stuff is fun!This message has been edited by Chiroptera, 06-08-2004 01:57 PM

Chiroptera, I agree, palaeontology accepts the Cambrian explosion as a real event. Despite most evidence pointing to a deep-time divergence, it is recognised that something special happened ~543 million years ago, & that the CE isn't just an artifact of preservation.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Well, there was a "real event" but it's not clear just how much it represents an unusually fast increase in diversity rather than an increase in size and the development of mineralised exo-skeletons.Our view of the "Cambrian Explosion" has changed considerably in the last 15 years and it isn't settled yet. But sadly creationists often don't recognise that fact.