The Cambrian Explosion
This article is an answer to a comment about the Cambrian Explosion, made by Tyronehster on October 2, 2012 at 10:30, in his article called Let's Talk Origins, placed on October 2, 2012, 08:11
As creationists love to quote the Cambrian Explosion as “evidence” that “evolution is wrong”, I would like to provide a few facts on the Cambrian Explosion. Facts creationists will never tell you about.
Firstly, I’ll briefly describe what the so-called Cambrian Explosion is.
The Cambrian Explosion was not an explosion (as in bombs exploding). It was the relatively rapid (in geological terms) diversification of complex animal life in part of what is called the Cambrian Period.
Buckland, in 1841, provides an early description of the phenomenon.
In those days these Cambrian sediments were the lowest (thus oldest) fossiliferous sediments known.
Darwin, in Origin of Species by Means of Natural Selection (1859), wrote the quote so often mined by creationists:
To the question of why we do not find rich fossiliferous deposits belonging to these…periods prior to the Cambrian system, I can give no satisfactory answer.
Creationists, true to their “kind”, always forget to mention the next three pages where Darwin actually explains why the Cambrian Explosion is observed as it is, for example the nature of the fossil record, etc.
As has been pointed out, no fossiliferous sediments have been found below those known fossiliferous Cambrian sediments at that time. To find those sediments was difficult, as life was confined to the oceans at that stage of the history of life. These sediments will thus be found on land only in very scarce geological conditions.
The findings so far
The result was that geologists and paleontologists knew where to look for precambrian life in those sediments. They found it. And lots of it. In the order of lower “marine sediments” to older “marine sediments”. First no life. Then complex organic molecules. Then prokaryotes. Then eukaryotes. Then multicellular organisms. Then, animals with, what can more-or-less be described as skeletons. In the early stages of the Cambrian Explosion. Then life diversifies dramatically.
After the invention of absolute dating methods, the Cambrian Explosion has been found as occurring around 530 million years ago. Depending on the location on earth, the Cambrian Explosion lasted for from around 5 million years (lowest) to perhaps 40 million years (highest).
Tyronehster writes : The Cambrian Explosion is a case in point. The more we learn about the introduction of complex animals on Earth, the more puzzling the Cambrian event becomes for evolutionary biologists.
This certainly is not true. The first fossils of multicellular organisms are found in former marine sediments, dating around 80 million years before the Cambrian Explosion. Those organisms of 585mya were soft bodied while those of 530mya (Cambrian Explosion) had developed exoskeletons and the very beginnings of what would eventually become our skeleton.
Tyronehster writes: The explosive appearance of the nearly all possible skeletal designs in the Cambrian fauna defies a natural process explanation.
This is untrue again. For example: Fish appear in the Silurian, non-avian reptiles in the Devonian, the first insects also in the Devonian, the first amphibians also in the Devonian, the first mammals in the Triassic and the first birds in the Jurassic.
Our Phylum, the Chordates, is possibly represented by fossils such as Haikouella lanceolata, resembling a small eel with a frilly dorsal fin. But, it also had a head, brain, heart, and cartilaginous bar along the back, the notochord. This marks it as perhaps the earliest chordate, the group that gives rise to all vertebrates. A great transition fossil. Very, very far from our “body plans”. We only appear 530 million years later.
Of the 30 phyla or so we know of, 5 to 9 evolved before the Cambrian Explosion (worms, sponges, jelly fish, etc.). At least 8 phyla evolved after the Cambrian Explosion .
Tyronehster writes: Yet, this is exactly what one would expect to see in the fossil record if the God of the Bible were responsible for the creation of animal life on Earth.
Well, according to the creationist straw man of the Cambrian Explosion it does. But, wishful thinking doesn't work in reality.
Buckland, W. (1841). Geology and Mineralogy Considered with Reference to Natural Theology. Lea & Blanchard. ISBN 1-147-86894-8.
Coyne, J.A.(2009).Why evolution is true. Oxford University press. 309pp.