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Author Topic:   Evolving the Musculoskeletal System
Percy
Member
Posts: 19108
From: New Hampshire
Joined: 12-23-2000
Member Rating: 3.1


Message 511 of 527 (600132)
01-12-2011 5:41 PM


The Beginnings of Bone
Found this over at http://neurodojo.blogspot.com/.../05/beginnings-of-bone.html, here's a very relevant excerpt pertaining to why what ICdesign is doing is so much easier than what we are doing:

Zen Vaulkes writes:

I could go on, but I have other things to do. I just couldn’t quite bring myself to be as taciturn as the Times reporter, who correctly but tersely wrote:

As it happens the evolutionists do have answers — but in a fossil record spanning many more billions of years than a literal interpretation of Genesis allows.

Given that the reporter probably had a deadline, I can understand why he didn’t take the time to do a more detailed refutation. It took me a good chunk of a day to read a few technical papers and try to bang out this quick summary about bone evolution, which is why these rhetorical questions are so effective. Being incredulous is easier than research.

I think we could dig out some good information about the current state of knowledge about the origin and evolution of bones, but it would take some effort. Someone in the last day or so posted a few pictures of creatures with more primitive bones than mammals, but it would probably be helpful if we could find examples of extant creatures with just a simple cartilaginous hard part or two. There's the single-celled diatoms (a type of algae) whose cell walls are made of silica.

--Percy


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 Message 512 by jar, posted 01-12-2011 5:48 PM Percy has responded

  
jar
Member
Posts: 31775
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.5


Message 512 of 527 (600133)
01-12-2011 5:48 PM
Reply to: Message 511 by Percy
01-12-2011 5:41 PM


Re: The Beginnings of Bone
If someone has access This paper on the Evolution of Bone might be interesting.


Anyone so limited that they can only spell a word one way is severely handicapped!

This message is a reply to:
 Message 511 by Percy, posted 01-12-2011 5:41 PM Percy has responded

Replies to this message:
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Percy
Member
Posts: 19108
From: New Hampshire
Joined: 12-23-2000
Member Rating: 3.1


Message 513 of 527 (600135)
01-12-2011 6:42 PM
Reply to: Message 512 by jar
01-12-2011 5:48 PM


Re: The Beginnings of Bone
Found a couple articles at Wikipedia about the earliest creatures with skeletons of some sort. Here's a brief excerpt about the Namacalathus, an Ediacaran fossil:

Wikipedia writes:






A U–Pb zircon age from the fossiliferous rock in Namibia and Oman provides an age for the Namacalathus zone in the range from 549 to 542 Ma, which corresponds to the Late Ediacaran. These organism and Cloudina are the oldest known evidence in the fossil record of the emergence of calcified skeletal formation in metazoans, a prominent feature in animals appearing later in the Early Cambrian.

...

The fossil is lightly calcified, preserved as calcite crystals; its original morphology is unknown.

This excerpt is from the Wikipedia article on Cloudinid:

Wikipedia writes:






They formed millimetre-scale conical fossils consisting of calcareous cones nested within one another; the appearance of the organism itself remains unknown.

...

Cloudinids are important in the history of animal evolution for two reasons. They are among the earliest and most abundant of the small shelly fossils with mineralized skeletons, and therefore feature in the debate about why such skeletons first appeared in the Late Ediacaran.

So the earliest examples of skeletons in the fossil record were very, very simple, but we know very little about these organisms.

--Percy

Edited by Percy, : Increase image margins.

Edited by Percy, : Grammar.


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jar
Member
Posts: 31775
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.5


Message 514 of 527 (600138)
01-12-2011 7:22 PM
Reply to: Message 513 by Percy
01-12-2011 6:42 PM


Re: The Beginnings of Bone
It also appears that bones and skeletons may have been a later development, that calcium based hard surfaces may have first developed externally with cartilage taking the place of bones internally.


Anyone so limited that they can only spell a word one way is severely handicapped!

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Taq
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Posts: 8207
Joined: 03-06-2009
Member Rating: 3.9


Message 515 of 527 (600213)
01-13-2011 11:56 AM
Reply to: Message 513 by Percy
01-12-2011 6:42 PM


Re: The Beginnings of Bone
So the earliest examples of skeletons in the fossil record were very, very simple, but we know very little about these organisms.

The earliest chordates had no bones, such as Haikouella:

http://en.wikipedia.org/wiki/Haikouella_lanceolata

Connective tissue is all that is needed. No bones.

In modern vertebrates like us we start with the same non-calciferous notochord as an embryo that later develops into the bony vertebral column.


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crashfrog
Inactive Member


Message 516 of 527 (600241)
01-13-2011 2:07 PM
Reply to: Message 506 by arachnophilia
01-12-2011 2:23 AM


Re: living transitional skeletons
eek, that's a clearly false notion of evolution. evolution is not directed, nor does it forbid convergence, nor does it necessitate that once an adaptation is successful that it be adopted across lineages

I guess I wasn't very clear. I was assuming that my remarks would be read in the context of IC's argument, which is that if skeletons evolved, then every species with a skeleton should contain individuals who have less-evolved skeletons. Remember? He keeps asking why, if the human skeleton evolved piece by piece over millions of years, why we don't see humans with piecemeal skeletons.

And the answer is because they've already evolved skeletons; every human being inherits the genes for a fully-evolved skeleton from their parents. No human being has to evolve their own skeleton, they already have a fully-evolved one that they inherited.

ICDesign has this notion that evolution is a kind of slow change that happens in individuals, where a fish grows legs and lungs and takes a step onto land. Of course, he looks around and doesn't see any of this happening at all, so naturally he doesn't believe in "evolution." He sees individuals growing into static adult forms and then not changing at all.

We keep trying to tell him that evolution is something that happens to populations, not to individuals, but ICDesign believes that learning things is not a good way to understand things, he believes that knowing the least about a scientific field puts you in the best position to assess its merit. So, naturally, we will be unable to convince him that evolution is not a slow change that happens to individuals, it's a slow change that happens to populations of individuals as a result of how individuals are born different from each other.

ICDesign is determined to be the person who knows the least about biology in these conversations because he believes that's the best way to judge conclusions in the field of biology. Of course, somehow I doubt he goes to doctors who have yet to attend medical school, or has his car maintenance done by people who have never in their lives seen automobiles. For some reason it's only science where ICDesign believes that the best way to know what's true is to know nothing at all.


This message is a reply to:
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Replies to this message:
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Kapyong
Member (Idle past 1784 days)
Posts: 344
Joined: 05-22-2003


(2)
Message 517 of 527 (600268)
01-13-2011 5:17 PM


Greetings ICDesign,

It is all too common for people to confuse the two meanings of the word "theory".

In popular terms, "theory" means a guess, or speculation. Thus the common phrase "just a theory" meaning "just speculation", "just an untested idea", merely a claim that might be true.

But,
in scientific terms, there is another, different, meaning to the word "theory" - it means an EXPLANATION.

Theories EXPLAIN facts

Theories explain the facts we observe :

Gravity is a fact, we observe its effects.
Gravitational Theory describes how gravity works.

Electricity is a fact, we use it everyday.
Electromagnetic Theory explains the details of how it operates.

Germs are a fact.
Germ Theory explains how they cause disease.

Evolution is a fact, it is observed.
The Theory of Evolution explains how it works.

the ToE is an EXPLANATION, NOT speculation

The Theory of Evolution is NOT "speculation about evolution" - that is NOT what the phrase means at all.

Rather -
the Theory of Evolution is the EXPLANATION for how evolution works, it models the behaviour of the FACTS of evolution, and allows predictions to be made.

Just as Electromagnetic Theory is the explanation or model of how electricity works.
Would one say "electricity is just a theory" ?
Of course not.

And Gravitational Theory is the explanation or model of how gravity works.
Would one say "gravity is just a theory" ?
Of course not.

And Germ Theory is the explanation or model of how germs cause disease.
Would one say "germs are just a theory" ?
Of course not.

Yet
some people say
"evolution is (just) a theory"

as if it means
"evolution is merely untested speculation" (false)

when it really only means
"evolution is an explanation, or model" (true)

Claiming "evolution is just a theory" indicates lack of understanding of the word, and how science operates, and that the ToE is an explanation for observed facts.

EVOLUTION = FACT & THEORY

Evolution is a FACT.
We observe evolution.
And,
the Theory of Evolution is the EXPLANATION, or model, for the observed facts of evolution.

Kapyong

Edited by Kapyong, : No reason given.

Edited by Kapyong, : Minor adds.


  
arachnophilia
Member (Idle past 319 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 518 of 527 (600273)
01-13-2011 5:35 PM
Reply to: Message 516 by crashfrog
01-13-2011 2:07 PM


Re: living transitional skeletons
crash,

oh. i see. i was having some difficulty making sense of what the heck he even meant.


This message is a reply to:
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crashfrog
Inactive Member


Message 519 of 527 (600275)
01-13-2011 5:44 PM
Reply to: Message 518 by arachnophilia
01-13-2011 5:35 PM


Re: living transitional skeletons
i was having some difficulty making sense of what the heck he even meant.

Don't worry about it; I should have been more clear. And I've had some ex parte conversations with him already.


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Dr Adequate
Member
Posts: 16107
Joined: 07-20-2006
Member Rating: 8.3


Message 520 of 527 (600324)
01-13-2011 11:45 PM
Reply to: Message 506 by arachnophilia
01-12-2011 2:23 AM


Re: living transitional skeletons
in any case, here are some living animals with various states of "hard spots" on the way to having a bony skeleton.

I think the consensus is that sharks are descended from bony fish.


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Replies to this message:
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Wounded King
Member (Idle past 2436 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 521 of 527 (600359)
01-14-2011 5:58 AM
Reply to: Message 520 by Dr Adequate
01-13-2011 11:45 PM


Re: living transitional skeletons
I think the consensus is that sharks are descended from bony fish.

I think the term bony fish might be a bit confusing here. Do you mean teleostomi, the actual group known as bony fish? Or do you mean fish which had some bony structures like placoderms or agnathans?

If you are saying that chondricthyes, including sharks, evolved from teleosts then that is pretty contrary to what I understood to be the case.

TTFN,

WK


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Dr Jack
Member (Idle past 447 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 522 of 527 (600363)
01-14-2011 6:32 AM
Reply to: Message 520 by Dr Adequate
01-13-2011 11:45 PM


Re: living transitional skeletons
I'm with Wounded King, sharks are not descended from teleosts, which is what I'd understand bony fish to mean.

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Dr Jack
Member (Idle past 447 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 523 of 527 (600364)
01-14-2011 6:46 AM
Reply to: Message 501 by ICdesign
01-11-2011 6:40 PM


The trouble with Creationists
Second of all, any system such as the first circulatory system has to be complete with the pipelines to every location, the heart fully developed and so-forth. I have brought all this up in great detail in the past and the lame answer comes back that this all developed at the same time. Even if that were possible (which it isn't) you have the catch 22 problem. The complete system would have taken eons of time to develop. How could life be possible during this time?

And this is the trouble with Creationists: you don't know your biology.

Pick up any decent textbook on the diverse biology and read it. You'll soon discover that there are animals living today that prove your argument completely wrong. There are animals in which the organs are simply suspended in fluid. Animals which have a sort of circulation system with no heart in which the fluid is moved simply by the motions of the animal. Animals with a primitive sort of heart - really nothing more than a bit of muscle that keeps the fluid moving. Animals with the separated lung/body circulation you see in humans, but an undivided heart so that the oxygenated and deoxygenataed bloods mix as it pumps, semi-divided hearts that improve the separation of the two and then hearts like ours which fully divide the two.

If you took the time to study even a little bit of biology you'd know how absurd your claims that such things couldn't exist and wouldn't work really are.


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Dr Adequate
Member
Posts: 16107
Joined: 07-20-2006
Member Rating: 8.3


Message 524 of 527 (600366)
01-14-2011 7:03 AM
Reply to: Message 521 by Wounded King
01-14-2011 5:58 AM


Re: living transitional skeletons
I just mean fish which have bones where sharks have cartilage.

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Replies to this message:
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Dr Jack
Member (Idle past 447 days)
Posts: 3507
From: Leicester, England
Joined: 07-14-2003


Message 525 of 527 (600369)
01-14-2011 8:23 AM
Reply to: Message 524 by Dr Adequate
01-14-2011 7:03 AM


Re: living transitional skeletons
No, I'm afraid not. The fish that have bones where the sharks have cartilage are all teleosts, it is generally accepted that elasmobranches (inc. Sharks) did not evolved from the teleost fish.

This message is a reply to:
 Message 524 by Dr Adequate, posted 01-14-2011 7:03 AM Dr Adequate has responded

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