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Evolutions unsolved questions!

Discussion of everything related to the Theory of Evolution.

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Postby Excalibur » Tue Dec 27, 2005 2:34 am

alextemplet wrote:What about walking fish like Acanthostega or Ichthyostega? Those were literally walking fish, exactly the missing links you claim do not exist.


The coelacanth fossils was estimated to be 410 million years of age. Now I would of thought this to be a good age whereby evolutionists could have claimed it to be the ancestor of all living creatures.

However the Acanthostega is a very primitive tetrapod from the Late
Devonian with eight fingers and toes.

How could a creature from the Devonian be our ancestor?

The so called "tetrapod fish" which you mention Acanthostega is found as anything close to a complete fossil that can be truly analyzed.

While it first off looks impressive as a transition--it has a body for swimming and four well-developed clear legs--upon later inspection it appears that this animal too is an amphibian.

The main noted similarity to fishes is the notochord and possible internal gill slits (many living amphibians also have gills, though they are external).

it is claimed that the aquatic Acanthostega developed limbs so it could have an advantage running out of the water to escape predators. However, there's a tradeoff: limbs are not as good for swimming as fins are.

Why would a fishlike creature begin to develop legs which themselves inhibit their ability to swim away from predators?

There simply is not a scenario whereby it is advantageous for an aquatic creature to develop limbs for organisms with poor fins for swimming would quickly get selected out by predatation over swimming organisms--long before true tetrapod limbs like Acanthostega had could develop on their own.

Given that Acanthostega had true limbs, it seems that the missing links...are still missing. Despite this alleged transitional fossil which bears a striking resemblance to many living forms, the origin of the defining characteristics of tetrapods, the limbs, is still an unsolved mystery to evolutionists. :(
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Postby mith » Tue Dec 27, 2005 4:17 am

Excalibur, what model do you propose we use instead of evolution?
Also, read up on punctuated equilibruim.
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Postby alextemplet » Tue Dec 27, 2005 4:32 am

As I understand it, there are two hypothesis as to how .Acanthostega evolved its legs.

First, it could've started as something like modern day mudskippers, which are literally amphibious fish. They can swim perfectly well, but can also hop about on land, and they are even capable of absorbing oxygen through their skin. This is exactly how primitive amphibians, and modern-day salamanders, breather. Salamanders do not have lungs, but breathe through their skin, and this is probably how the first amphibians breathed. Anyway, in a world with plenty of predatory fish in the water but few large predators on land, the advantage of terrestrial life is obvious. Fish fins already have a bone structure very similar to tetrapod limbs, and mudskippers can use the lobefins to good effect on land and in the water, and they can breathe in both environments, so the concept of a tetrapod ancestor being similar to that and thereby evolving into amphibians, reptiles, birds, and mammals is actually a pretty easy conclusion.

Secondly, some have hypothesized that the tetrapod ancestors lived in mangrove swamps, where shallow water was heavily obstructed by tree roots. In such an environment, legs are actually better to have than fins, since crawling through the roots may be easier than swimming through them. This drove the evolution of legs from fins, both of which, as mentioned above, have the same underlying bone structure. So legs, and possibly lungs (perhaps they evolved from a lobe-finned lungfish?), had already evolved before the animals moved onto land.

I suppose both hypothesis are valid to an extent. I am currently not sure which one is more widely accepted, though in my own opinion the first is the more convincing. Perhaps someone else can supply additional details that I have failed to include.
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Postby Squawkbox » Thu Jan 19, 2006 9:34 pm

mithrilhack wrote:Excalibur, what model do you propose we use instead of evolution?
Also, read up on punctuated equilibruim.


i no im not excalibur but mebi you should consider other points of view and their arguments from a neutral point of view there are holes in all of them and even Richard Dawkins (an evolution reasearch guy) admits he requires faith to believe in evolution so i suppose its not a matter of facts but one of faith and which you can have the most faith in after considering the limited facts that are available. Remember evolution is only a theory after all. It is not proven fact although it is taught in most schools as fact. When i did it at school the teacher never mentioned this point once. I think its a shame students cant be given a more open minded view of where we came from. I dont think we'll ever really know for sure.
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Postby mith » Fri Jan 20, 2006 12:10 am

There is a difference between the definition of theory commonly used and the definition of theory used in science. And look on the evolution thread, ID isn't a science. That's why we have separation of church and state.
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Postby Linn » Sun Jan 29, 2006 8:06 pm

Darwin believed in creation

In his conclusion to THE ORIGIN OF SPECIES,
he wrote about the grandeur of the "view of life, with its several powers, having been originally breathed by the creator into a few forms or into one,"
He left the subject open to examination.
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Postby Linn » Sun Jan 29, 2006 8:12 pm

Oh and by the way
evolution is not a fact its a theory.
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Postby canalon » Sun Jan 29, 2006 8:40 pm

Linn wrote:Oh and by the way
evolution is not a fact its a theory.


As well as gravitation, electricity and all scientific theories. Theory in science is the word used for a something that gives a coherent models of related facts. So the fact that it is a theory doesn't mean anything about the validity of said model (evolution, gravity etc...)
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Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
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Postby Linn » Sun Jan 29, 2006 9:58 pm

there are no related facts.
Is evolution REALLY in harmony with the discoveries of modern science?
Lets examine some related issues.
Respectfully,
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Postby Linn » Sun Jan 29, 2006 10:08 pm

" divergence exists because the evidence is unsatisfactory and does not permit any certain conclusion" -W,R Thompson

If, one wants to claim there is evidence.
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Postby Linn » Sun Jan 29, 2006 10:24 pm

and

gravitation and electricity are not theories
but fact
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Postby mith » Mon Jan 30, 2006 12:27 am

Gravity is a theory. http://en.wikipedia.org/wiki/Gravity
Two examples we're familiar with are Newton's Law(which is a special type of theory) of Universal Gravitation and Einstein's Theory of Relativity.

Similar article for electricity
http://en.wikipedia.org/wiki/Electromagnetism

People really should read my posts and save me the trouble of requoting myself :(
There is a difference between the definition of theory commonly used and the definition of theory used in science.
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