THE CAMBRIAN EXPLOSION (no, not an industrial accident in Wales ...)

... but the proliferation of new life forms that occured some half billion years ago in the Cambrian geological period.

Prior to that time, lifeforms were primitive microscopic plants and animals or simple animals similar to modern tube worms. Vast deposits of fossilised creatures were found in the so-called "Burgess Shales" in northern North America, which due to their geologic makeup, preserved the fossils to a remarkable degree due to the soft sea bed mud which eventually became the shales. Impressions of small soft bodied creatures were found preserved in great detail.

It is during this period that most of the features common to modern life came to be; eyes, exo- and endo-skeletons and the beginnings of a distributed nervous system.

Perhaps the most familiar of these creatures which evolved around that time was the trilobite which occurred in a great range of sizes.

Below are some artist's impressions of some of the creatures, based on fossil imprints. The thing that looks like a white worm with legs, in the first picture is named "halluciginia" and I can see why ...

Re: THE CAMBRIAN EXPLOSION (no, not an industrial accident in Wales ...)

Very interesting and great pictures Rob, they remind me of the aliens in the space comics I used to read as a kid, little did I know such creatures existed on our own planet. I think the world is a lot older than the experts make out it is, so is life on it older, I would even imagine that there were civilisations long before we know of, if it were not for fossils and rock carvings we would know very little about the past, makes you wonder what the folks in another billion years will have to help them understand us, can't see all this digital stuff they are storing our records on lasting that long, maybe that's what happened to the old civilisations, everything on computer then bang!, time to get the old hammer and chisel out again methinks.

Re: THE CAMBRIAN EXPLOSION (no, not an industrial accident in Wales ...)

....interesting Rob

Re: THE CAMBRIAN EXPLOSION (no, not an industrial accident in Wales ...)

Jem, the period before the Cambrian period, known as the pre-Cambrian, lasted from the formation of the Earth, approximately 4.5 Gigayears ago, to the Cambrian, 0.5 Gigayears ago.

Life in it's most primitive forms is now believed to have arisen much earlier than was thought not so long ago; as early as 3.5 Gigayears ago in fact, according to fossil impressions of cyanobacteria found in Australia. It seems that life will evolve anywhere as soon as the conditions are suitable. The period of the pre-Cambrian believed to contain life lasted for 7 times as long as all the other geologic periods put together.

Interestingly, structures known as Stromatolites (agglomerations of bio-films containing bacteria that built up in much the same way as coral reefs) still exist today in the shallow seas around Australia. These are believed to be virtually the same as the very first lifeforms to have evolved.

Re: THE CAMBRIAN EXPLOSION (no, not an industrial accident in Wales ...)

Indeed, trilobites were in existence half a billion years ago, but your third "photo" begs the question of the bi-ped under water and, in the same "photo" the cosyness of the two creatures cuddled up in what looks like an oval aluminium container ready to be cooked for dinner also looks a bit strange!

However, having said that, I do find the thread fascinating because I have two little trilobite fossils given to me, and also another creature fossil, the name of which I cannot recall right now.

I have also studied pre-historic palaentology, but not in the greatest depth, so the probability is that life on earth did indeed begin in primaeval swamps, and not that dodgy old tale about Adam and Eve.

Incidentally, one gigayear is 100,000,000 years!

Re: THE CAMBRIAN EXPLOSION (no, not an industrial accident in Wales ...)

Ha ha! Yes Mollie, it does look a bit like an ape like biped shambling along doesn't it? However on close inspection, the 'arm' is in fact another of those sponge type things in the background and the 'two' creatures in the frying pan are actually just one, moving away from the foreground. It looks like some sort of primitive arthropod, much like the sea-slater of today which lives in crevices in shoreline rocks.


Interestingly again, the modern horseshoe crab is believed also to be virtually unchanged from its remote ancestors, even down to having 'blue' blood caused by the presence of haemocyanin instead of haemoglobin in its blood.

Re: THE CAMBRIAN EXPLOSION (no, not an industrial accident in Wales ...)

Moving forward in time some 300 to 400 million years to the age of the dinosaurs, the Cretaceous, Jurassic and Triassic eras, it now appears that many of the smaller dinosaurs actually had primitive feathers as shown by feather shaped impressions in certain fossils and recently, I believe, trace amounts of beta-keratin (the principle protein in modern bird feathers) has been found. This gives much greater weight to the theory that birds evolved directly from small Therapods via such creatures as Archaeopteryx (ancient bird). It is not certain as to whether Archaeopterx could fly or was simply a glider, although probably a superior glider to the Pterosaurs due to much better control of the flight surfaces via the feathers. Despite what the gainsayers say, this to my mind, is proof positive of evolution in action.