The Cambrian Explosion
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05-07-2017, 06:02 AM
RE: The Cambrian Explosion
(05-07-2017 05:52 AM)SeaJay Wrote:  
(05-07-2017 05:14 AM)TheInquisition Wrote:  The Cambrian explosion occurred over a period of 20 million years, how is this similar to the creation myth?

The bible asserts that birds were created in the same period as life in the oceans, how is this similar to the scientific evidence?

Birds were a branch-off from dinosaur ancestors, much later:

[Image: 1-image2dinosaursizeevolution.jpg]

There's another blatant error made in Genesis- whales. Whales evolved from Pakicetus, an amphibious land animal!

[Image: 11419321426_351855d846.jpg]

Further down in the Genesis myth (1:30) it implies that every animal ate plants before the fall of man. Do you fully understand how incredibly wrong that is?

There is no way a reading of Genesis in the light of science can recover from being anything but a primitive myth created by an ignorant people, the ignorance of Genesis jumps out at you, the only way it remains credible is through childhood indoctrination. Once you examine it outside the Christian envelope, it completely falls apart.
Thank you for this Inquisition. Much to ponder

"Further down in the Genesis myth (1:30) it implies that every animal ate plants before the fall of man. Do you fully understand how incredibly wrong that is?"

Far as I know the animals were would have been herbivores, carnivores and omnivores? Is your point that Genesis implies they 'only' ate plants?

Yes, of course with any biblical verse it's open to interpretation (post-hoc rationalization), but Ken Ham and other creationists assert just that:

What were the tyrannosaurs really like?

Gods derive their power from post-hoc rationalizations. -The Inquisition

Using the supernatural to explain events in your life is a failure of the intellect to comprehend the world around you. -The Inquisition
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05-07-2017, 06:07 AM
RE: The Cambrian Explosion
(05-07-2017 05:41 AM)SeaJay Wrote:  The precise reason for my anxieties is what I've read about it. Basically, and as Dawkins said in the Blind Watchmaker:

"It's as though they were just planted there, without any evolutionary history" (pg 229).

I've not read the entire book though so obviously I might be taking it out of context. I do know Dawkins doesn't belief in gods so I know I'm missing something.

You're missing more than something:

"It is as though they [fossils] were just planted there, without any evolutionary history. Needless to say this appearance of sudden planting has delighted creationists. ...Both schools of thought (Punctuationists and Gradualists) despise so-called scientific creationists equally, and both agree that the major gaps are real, that they are true imperfections in the fossil record. The only alternative explanation of the sudden appearance of so many complex animal types in the Cambrian era is divine creation and (we) both reject this alternative." (Dawkins, Richard, The Blind Watchmaker, W.W. Norton & Company, New York, 1996, pp. 229-230)

While it can be gleaned from this quote, it needs to be pointed out specifically that this is a discussion of Dawkins' disagreements with Stephen Jay Gould and Niles Eldredge over Punctuated Equilibrium and Dawkins is here discussing the fact that Gould and Eldredge would agree with him that the "sudden appearance" of animals in the Cambrian Explosion is really the result of the imperfections of the fossil record.

The part in the ellipsis is an explanation for this, as follows:

"Evolutionists of all stripes believe, however, that this really does represent a very large gap in the fossil record, a gap that is simply due to the fact that, for some reason, very few fossils have lasted from periods before about 600 million years ago. One good reason might be that many of these animals had only soft parts to their bodies: no shells or bones to fossilize. If you are a creationist you may think that this is special pleading. My point here is that, when we are talking about gaps of this magnitude, there is no difference whatever in the interpretations of 'punctuationists' and 'gradualists'."]
It's quote 40.

Quote:EDIT: I've also read that it took place over about 5 million years. Isn't that supposed to be insignificant in evolutionary time scales?

Maybe this Wikipedia article will help you with time scale:

https://en.wikipedia.org/wiki/Timeline_o...ry_of_life

The first revolt is against the supreme tyranny of theology, of the phantom of God. As long as we have a master in heaven, we will be slaves on earth.

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05-07-2017, 06:40 AM
RE: The Cambrian Explosion
(05-07-2017 06:07 AM)Szuchow Wrote:  
(05-07-2017 05:41 AM)SeaJay Wrote:  The precise reason for my anxieties is what I've read about it. Basically, and as Dawkins said in the Blind Watchmaker:

"It's as though they were just planted there, without any evolutionary history" (pg 229).

I've not read the entire book though so obviously I might be taking it out of context. I do know Dawkins doesn't belief in gods so I know I'm missing something.

You're missing more than something:

"It is as though they [fossils] were just planted there, without any evolutionary history. Needless to say this appearance of sudden planting has delighted creationists. ...Both schools of thought (Punctuationists and Gradualists) despise so-called scientific creationists equally, and both agree that the major gaps are real, that they are true imperfections in the fossil record. The only alternative explanation of the sudden appearance of so many complex animal types in the Cambrian era is divine creation and (we) both reject this alternative." (Dawkins, Richard, The Blind Watchmaker, W.W. Norton & Company, New York, 1996, pp. 229-230)

While it can be gleaned from this quote, it needs to be pointed out specifically that this is a discussion of Dawkins' disagreements with Stephen Jay Gould and Niles Eldredge over Punctuated Equilibrium and Dawkins is here discussing the fact that Gould and Eldredge would agree with him that the "sudden appearance" of animals in the Cambrian Explosion is really the result of the imperfections of the fossil record.

The part in the ellipsis is an explanation for this, as follows:

"Evolutionists of all stripes believe, however, that this really does represent a very large gap in the fossil record, a gap that is simply due to the fact that, for some reason, very few fossils have lasted from periods before about 600 million years ago. One good reason might be that many of these animals had only soft parts to their bodies: no shells or bones to fossilize. If you are a creationist you may think that this is special pleading. My point here is that, when we are talking about gaps of this magnitude, there is no difference whatever in the interpretations of 'punctuationists' and 'gradualists'."]
It's quote 40.

Quote:EDIT: I've also read that it took place over about 5 million years. Isn't that supposed to be insignificant in evolutionary time scales?

Maybe this Wikipedia article will help you with time scale:

https://en.wikipedia.org/wiki/Timeline_o...ry_of_life
Thanks for this Szuchow!

“I am so clever that sometimes I don't understand a single word of what I am saying.” ~ Oscar Wilde
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05-07-2017, 08:48 AM (This post was last modified: 05-07-2017 04:25 PM by TheBeardedDude.)
The Cambrian Explosion
The Cambrian Explosion?!
[Image: vJCUaItP2rgBwso3rfaTJzqLQ2TG1S-1N5PlmWM7...fda8e18bc6]

Now that is a subject worth discussing!

The Cambrian Explosion is quite the interesting event and it is indeed a subject where you won't find a ton of consensus among paleontologists about the primary mechanisms driving it. What you will find is a consensus that it isn't a problem for evolution or the history of life and probably also a consensus that the word "explosion" is a huge misnomer that has inadvertently given the impression of an instantaneous appearance of life on Earth. It isn't so.

Some basic facts about the Cambrian Explosion:
1) It occurred over millions of years (maybe 10 million years or more). The beginning of the Cambrian is defined based on the appearance of vertical burrows, which indicate that animal life had evolved a new behavior for burrowing through sediment for food and/or shelter. The faunas of the Cambrian Explosion won't appear for several more million years, but...
2) animal life was already going strong and had been for tens of millions of years. The animals that had been alive from the Ediacaran (and probably back to the Cryogenian) up to the Cambrian were quite weird (the Ediacaran Faunas are very bizarre) and mostly soft-bodied. The soft-bodied nature of animal life meant...
3) most animals up to the early Cambrian would have been extraordinarily difficult to preserve. That is because they are soft-bodied and because...
4) the depositional environments on Earth weren't quite like they are today. The Ediacaran faunas, for instance, are preserved in a way (sometimes called a "death mask") that doesn't really happen again after the Phanerozoic Eon begins (the Eon that starts when the Cambrian starts. The Eon we are currently in). The reason those environments were so different is probably because life wasn't as abundant or diverse as it is today (or during the bulk of the Phanerozoic). Life interacts with its environment and can change the physical and chemical parameters. For instance, organisms burrowing into the sediment can mix it up and help bury organisms and also oxygenate the sediments for organisms to live in (where they can then die and become preserved or leave behind traces). Back to those...
5) trace fossils that define the beginning of the Cambrian. They tell us that the same vermiform organisms alive in the oceans today, were there around the beginning of the Cambrian. Meaning that their ancestors were alive in the Ediacaran. And fossils like Kimberella are similar enough to molluscs that many consider it to be an ancestral mollusc (not everyone is convinced of this because it lacks a radula, but its other characters are very similar to many molluscs). So animals that were primarily soft-bodied were doing just fine before the Cambrian Explosion. That's because...
6) the Cambrian Explosion is primarily about the appearance of hard-bodied organisms in the fossil record (organisms with an exoskeleton mainly). With the beginning of the Cambrian, animal life was becoming more diverse. That increase in diversity meant an increase in predation (for the moment we can also consider grazing organisms to be "predating" another organism too). That selection pressure would have driven an evolutionary arms race between predator (who would have also been subject to predation pressures) and prey. The result was an increase in armor and the development of organs for better finding prey and avoiding predators (like eyes). Why did it take so long for this to happen?
7) Before the Cambrian, the oceans were pretty low diversity and very low in oxygen. The concentration of oxygen is directly proportional to the amount and size of respiring life that can survive in it. So animal life was doing well before the Cambrian Explosion, but it was primarily a low diversity fauna of very small organisms. The smaller the organism and the more soft-bodied it is (coupled with environments that had a low preservation potential), the harder it is to preserve and then find in the rock record. But the signs are there in what fossils we do find, as well as in the geochemical record. In fact...
8) the geochemical record probably tells us the rest of the story. During the Cryogenian the Earth went through 2-3 phases of being covered from pole to equator in ice (land and ocean both covered in ice during the Snowball Earth events). One potential side effect of this would have been the grinding up and mass movement of sediment off of the continents into the ocean. This is hugely important because it would have introduced iron (a primary limiting nutrient in the oceans) and phosphorous (another limiting nutrient and one that can only come from the rock record or the remineralizaton of organic matter in sediments). This introduction of large quantities of nutrients seems to have helped life increase in diversity and complexity (as evidenced by the Ediacaran fauna). This is an important precursor because...
9) it would have helped facilitate a massive change to the global carbon cycle. That is because you'd have a brand new standing crop of biomass. This new abundance of organisms would have helped sequester CO2 from the atmosphere into the biosphere (the living organisms) and the lithosphere (organic matter being buried in sediments). This is hugely important because...
10) sequestering the organic matter prevents it from being oxidized back into CO2. Meaning that the concentration of oxygen in the atmosphere and oceans would have begun to increase as the quantity of living organisms continued to increase. More oxygen in the water and atmosphere would have helped facilitate the evolution of larger bodied organisms. And to add to this...
11) sequestering CO2 as organic matter would have also helped lower the overall temperature of the early Cambrian Earth. The Cryogenian is weird and also quite debatable as to how it happened and how the Earth came out of it. But other than these phases of glaciation, the Proterozoic and early Phanerpzoic Earth were very warm. And warm water doesn't hold as much oxygen (or any dissolved gas) as cooler water. So a cooler global ocean that is less variable, would be more conducive to life. That is because it isn't just necessary that oxygen concentrations are high enough for respiring life, but the concentration of oxygen can't get too low due to the diurnal cycles. Meaning that it doesn't do respiring organisms any good for oxygen concentrations to be good at night when it is cooler, only for the oceans to get too hot during the day (which would cause the oceans to become dysoxic to anoxic in places). And on top of that...
12) most macroinvertebrates can't withstand temperatures in excess of ~34°C for prolonged periods of time. So the oceans becoming more thermally stable would have also benefited the very organisms that will eventually begin to diversify during the Cambrian Explosion. And then on top of all of this...
13) the temperature of the water as well as the concentration of CO2 in it, will effect the solubility of aragonite and calcite (each are CaCO3). These are the two primary minerals used in the exoskeletons of organisms (even for some arthropods they use calcite to reinforce their exoskeletons. That is why the claws of crabs are so tough. And early Arthropods present in the Cambrian used calcite to reinforce their shells too, like trilobites). This change in solubility would have made it easier to produce shells. And shells are much easier to preserve than soft-bodied organsims because the shells and skeletons don't decompose. So as long as they get buried before being destroyed, they should produce a fossil (which could later be dissolved away by groundwater but that could still leave behind a mold or cast or a recrystallized fossil or a permineralized fossil or a fossil with a new mineralogy having precipitated out in its place in a process called replacement).

So what that ultimately means is that the "Explosion" of hard-bodied organisms was likely a consequence of:
1) increased nutrient input into the oceans
2) change in the global carbon cycle due to an increase in standing biomass
3) sequestration of CO2
4) increase in O2
5) reduction in global mean temperatures and stabilization of temperatures
6) increased concentrations of carbonate ions in the water and increased alkalinity facilitating the development of biomineralization in animals


Two additional important points:
1) Weird Cambrian preservation has produced a diversity observed in the fossil record that is very rare. The Burgess Shale and the Chengjiang faunas are both early Cambrian and both have exceptionally well-preserved soft-bodied animals (the latter has the oldest known chordate, our direct ancestor). These extremely rare instances of preservation happen to be in the early Cambrian and if not for them, we wouldn't know about the bulk of the animals preserved. We wouldn't know about the early Chordates nor the priapulid worms nor any of the primarily soft-bodied animals. Meaning that if we didn't have these two fossil localities, the Cambrian Explosion wouldn't look anywhere near as sudden or odd with respect to the fossil record. Basically, we got lucky for those preservation conditions to have existed and even luckier someone found them.

The Burgess Shale, for instance, is quite intriguing. It is a locality up in the Canadian Rockies and is only accessible for a few months out of the year in the summer. In the mid-1800's, it was discovered by accident when a horse kicked over a slab that had a weird fossil on it. The Burgess Shale is part of a turbidite, which is an underwater mass slump deposit that occurs on the edge of a continental shelf. The organisms preserved were alive on the upper portion of the shelf when it became unstable and collapsed, taking all of them with it. They were deposited in the debris flow along the abyssal plain and essentially buried alive. Those organisms were deposited suddenly in a debris flow into an environment with very little to no oxygen. This prevented them from decomposing and left us with fossils that are so well preserved, you can still dissect them. And on top of that, different imaging techniques reveal new details. For instance, x-raying the trilobites reveals the antennae, legs, and gills. These are all structures that are almost never preserved with trilobites during the nearly 300 million years they were around. So the Cambrian Fauna is in part weird and extremely diverse because of pure dumb luck (lucky for us but not so much for them).

2) it was never an "explosion." This is pretty much the same story as the tale of it being called the Big "Bang." It is a misnomer. The fossils of the early Cambrian appear "suddenly" with respect to geology. What that means is that it occurred over millions of years. So it wasn't so much an "explosion" because that implies that the diversification would have been observable to a human within a matter of seconds, minutes, hours, days. That was never what it meant. Cambrian "Explosion" really just meant that there is a point in the rock record where the quantity and diversity of fossils increases rapidly over a short stratigraphic distance.

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05-07-2017, 09:06 AM
RE: The Cambrian Explosion
(05-07-2017 01:55 AM)SeaJay Wrote:  EDIT: Ironically, the best explanation I've read (currently) about the Cambrian Explosion, comes from this Christian website who uphold the theory of Evolution.

http://biologos.org/common-questions/sci...-explosion

Here is an alternate explanation from a Christian website that denies the theory of evolution.

https://answersingenesis.org/fossils/fos...explosion/

The information in ancient libraries came from real minds of real people. The far more complex information in cells came from the far more intelligent mind of God.
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05-07-2017, 09:07 AM
RE: The Cambrian Explosion
A textbook from a seminar-style class I've taken on the Cambrian Explosion: https://www.amazon.com/Cambrian-Explosio...+explosion

It has some errors in it because it is a first edition of a textbook, but it gives some really good info if you want much more detailed information from the paleontology community.

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05-07-2017, 09:07 AM
RE: The Cambrian Explosion
(05-07-2017 09:06 AM)theophilus Wrote:  
(05-07-2017 01:55 AM)SeaJay Wrote:  EDIT: Ironically, the best explanation I've read (currently) about the Cambrian Explosion, comes from this Christian website who uphold the theory of Evolution.

http://biologos.org/common-questions/sci...-explosion

Here is an alternate explanation from a Christian website that denies the theory of evolution.

https://answersingenesis.org/fossils/fos...explosion/

Translation: here is some anti-science religious propaganda from some morons who think they know science better than scientists

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05-07-2017, 09:11 AM
RE: The Cambrian Explosion
(05-07-2017 09:06 AM)theophilus Wrote:  
(05-07-2017 01:55 AM)SeaJay Wrote:  EDIT: Ironically, the best explanation I've read (currently) about the Cambrian Explosion, comes from this Christian website who uphold the theory of Evolution.

http://biologos.org/common-questions/sci...-explosion

Here is an alternate explanation from a Christian website that denies the theory of evolution.

https://answersingenesis.org/fossils/fos...explosion/
URGH, bloody hell. Just looked at that as well. "It could be the great flood", piss off will you.

"I don't do magic, Morty, I do science. One takes brains, the other takes dark eye liner" - Rick
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05-07-2017, 09:14 AM
RE: The Cambrian Explosion
(05-07-2017 09:07 AM)TheBeardedDude Wrote:  Translation: here is some anti-science religious propaganda from some morons who think they know science better than scientists

We don't claim to know science better; we claim we know history better. There is one historical question that must be answered before we try to understand nature. Was the universe created by God or did it come about entirely as a result of natural processes? The belief that the earth is billions of years old and that life came about by a process of evolution is the result of accepting the second alternative. Those who deny evolution do so because we accept the first answer.

https://clydeherrin.wordpress.com/2014/0...t-science/

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05-07-2017, 09:17 AM
RE: The Cambrian Explosion
(05-07-2017 09:06 AM)theophilus Wrote:  
(05-07-2017 01:55 AM)SeaJay Wrote:  EDIT: Ironically, the best explanation I've read (currently) about the Cambrian Explosion, comes from this Christian website who uphold the theory of Evolution.

http://biologos.org/common-questions/sci...-explosion

Here is an alternate explanation from a Christian website that denies the theory of evolution.

https://answersingenesis.org/fossils/fos...explosion/

Answers in Genesis... Laugh out load

You funny

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