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Author Topic:   Transitional fossils not proof of evolution?
smegma
Inactive Member


Message 181 of 223 (333536)
07-19-2006 8:40 PM
Reply to: Message 178 by NosyNed
07-19-2006 8:34 PM


Re: What is a transitional.
"Do you want to wait for a practicing scientist to discuss this? Or are you willing to talk to some of us who have done a bit more reading in the area than you may have?"
so you're not a scientist.

This message is a reply to:
 Message 178 by NosyNed, posted 07-19-2006 8:34 PM NosyNed has replied

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NosyNed
Member
Posts: 9006
From: Canada
Joined: 04-04-2003


Message 182 of 223 (333538)
07-19-2006 8:45 PM
Reply to: Message 181 by smegma
07-19-2006 8:40 PM


A scientist
No, I am not. Could you explain how that makes a difference to the nature of the arguments?
What it should do is make you want me to supply more back up than you would from an expert in a particular field. If one of our biologists gives you a definition or tells you what is done it makes sense to be more likely to take that at face value. If a non-expert gives you some information you should be more inclined to ask for support and an explanation.
I expect and welcome that.
ABE
However, that is all a bit of a red herring. We are trying to get a very clear picture of what you think a transitional should be.
Edited by NosyNed, : added a bit more commentary

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NosyNed
Member
Posts: 9006
From: Canada
Joined: 04-04-2003


Message 183 of 223 (333540)
07-19-2006 8:53 PM
Reply to: Message 181 by smegma
07-19-2006 8:40 PM


Re: What is a transitional.
While we are at it here are a couple of other threads discussing transitionals:
"Archaeopteryx; bird or reptile, or both?"
The Definition and Description of a "Transitional"

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Percy
Member
Posts: 22606
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 184 of 223 (333541)
07-19-2006 8:53 PM
Reply to: Message 173 by smegma
07-19-2006 8:16 PM


Re: What is a transitional.
smegma writes:
that means everyone has their own version of what the definition of "transitional"...
There's an explanation lying behind Nosy's way of responding to your question. The issue of transitionals has been addressed here many times, and experience has shown that creationists rarely accept the scientific definition of transitional, and that they ignore some subtle distinctions between transitionals at different classification levels, i.e., species, genus, order, family, etc.
So Nosy was just trying to protect himself from giving a detailed answer about transitionals only to have you reply, "That's not what I consider a transitional, and I don't care if science thinks that's a transitional, it isn't."
smegma writes:
For me a "transitional fossil" is a fossil that's part say fish and part frog.
If we approach this more generally and ask about transitionals between fish and amphibians, a number of transitionals appear in the fossil record. The most famous is the Coelacanth, of which there is actually a modern representative. The Coelacanth is a relative of the ancestor of tetrapods, which are land-based animals. Much closer relatives have also been found, but perhaps this is enough for now until we clarify the types of transitionals that you'll find acceptable.
--Percy

This message is a reply to:
 Message 173 by smegma, posted 07-19-2006 8:16 PM smegma has replied

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RAZD
Member (Idle past 1482 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 185 of 223 (333544)
07-19-2006 8:57 PM
Reply to: Message 174 by smegma
07-19-2006 8:20 PM


welcome to the fray, btw.
When replying, if you notice the upper left corner of the post you are replying to there are two buttons ...

Normal: (*) Peek Mode: (_)

"Peek Mode" allows you to "peek" at the formating that others used to see how things (like quote boxes) are done.
When it comes to quote boxes ...
type [qs]it's easy[/qs] and it becomes:
it's easy

"All fossils are transitional."
explain.
All organisms are in transition. Evolution is the change in species over time. There is a constant level of change (caused by mutations) balanced by a constant level of selection (survival or mating) that results in gradual change over time no matter how "static" the species appears to be.
Fossils are like snapshots of the past -- not every "picture" was taken, not every "picture" came out with a good exposure (some are too distorted and discolored to see clearly).
But think of life as a movie, with each individual as a "frame" in the movie -- the fossil is one frame in a long line of frames that when viewed one after the other show gradual change from, say a reptile to a mammal, and each one is very similar to the one before and after but less similar to the ones further away.
The span of change as seen in the fossil record can cover millions of years, so it can be very gradual indeed.
But even then there are examples of such transitions.
Asking you to define what you think is a transitional is not because it is an undefined term, but rather because this is a way to understand what you think it means so we can get on the same footing.
Enjoy.
Edited by RAZD, : added color, lines

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smegma
Inactive Member


Message 186 of 223 (333545)
07-19-2006 9:09 PM
Reply to: Message 184 by Percy
07-19-2006 8:53 PM


Re: What is a transitional.
"If we approach this more generally and ask about transitionals between fish and amphibians, a number of transitionals appear in the fossil record. The most famous is the Coelacanth, of which there is actually a modern representative."
coelacanths are still around and they have not "evolved".200 coelacanths were caught many times in different parts of the world.

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RAZD
Member (Idle past 1482 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 187 of 223 (333547)
07-19-2006 9:27 PM
Reply to: Message 186 by smegma
07-19-2006 9:09 PM


coelacanths and transitions
coelacanths are still around and they have not "evolved".
Actually the coelacanths alive today are different species from the ones millions of years ago.
http://www.dinofish.com/
DINOFISH.COM - Weird Bodies Frozen in Time
The living coelacanths, Latimeria chalumnae,and Latimeria menadoensis are possibly the sole remaining representatives of a once widespread family of Sarcopterygian (fleshy-finned) coelacanth fishes (more than 120 species are known from fossils)all but one of which disappeared at the end of the Cretaceous, 65 million years ago.
The coelacanth appears to be a cousin of Eusthenopteron, the fish once credited with growing legs and coming ashore ~360 million years ago. Today, scientists prefer to cite the tongue-twisting fossil candidates: icthyostega, panderichthys, acanthotega, and the newly discovered Tiktaalik roseae (2004), as the ancestor(s) of all tetrapods-amphibians, reptiles, and mammals, including ourselves.
With a couple of exceptions ancient coelacanths were small, seldom exceeding 55 cm. ... Today's coelacanths can reach almost six feet (2 meters) in length and weigh up to 150 or more lbs,(the giant Mozambique female shown on this site was 180 centimeters long and 95kg) but they are usually somewhat smaller, particularly the males, which average under 165cm.
The backbone of this fish is composed of a fluid-filled cartilaginous tube, which provides a firm yet flexible support for muscles. Hollow fin spines, identified in fossils, are what got the fish its name- "coelacanth" which literally means 'hollow spine'from the Greek.
Color used to highlight the some of the noticable change in species over time from the ancient to the modern species.
Interesting reading, yes. But the question is not how slow some transitions are or how fast some others are, but in what constitutes a transition that we can agree on.
Enjoy.

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This message is a reply to:
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Percy
Member
Posts: 22606
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 188 of 223 (333548)
07-19-2006 9:43 PM
Reply to: Message 186 by smegma
07-19-2006 9:09 PM


Re: What is a transitional.
smegma writes:
coelacanths are still around and they have not "evolved". 200 coelacanths were caught many times in different parts of the world.
It isn't the modern coelacanth that is the relative of the transitionals to tetrapods, but ancient ones. You're probably thinking that extinct species with modern representatives couldn't possibly be near relatives of the tetrapods that emerged a few hundred million years ago, but that's probably because you're making the mistake of assuming that all populations of a species evolve the same way, and that's not the case. Some Coelacanth populations (actually, their relatives) evolved significantly, some to eventually become the tetrapods, and some did not.
Anyway, would it help if we became more specific about transitional fossils between fish and amphibians?
--Percy

This message is a reply to:
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NosyNed
Member
Posts: 9006
From: Canada
Joined: 04-04-2003


Message 189 of 223 (333549)
07-19-2006 9:46 PM
Reply to: Message 186 by smegma
07-19-2006 9:09 PM


That which has not evolved.
coelacanths are still around and they have not "evolved".200 coelacanths were caught many times in different parts of the world.
You making this statement as if it is relevant to something being (or being a representative) of a transitional shows one of the common misunderstandings.
You are a descendant of your grandfather and are different from him. The fact that he may still be around doesn't make you any less a decendent from him nor make him less a transitional form between your great, great grandfather and yourself.
If a population of amphibians split into a group which, over time, evolved into reptiles that doesn't say that the rest of the population couldn't have stayed as amphibians.
Fish are highly successful forms. The fact that there are environments where some fish might do well if they have some ability to survive out of water doesn't say that ALL the fish have to abandon the ocean.
Somewhere back there fish that were like the coelacanths took a turn toward the land. That doesn't mean that the entire population was in the same place and under the same environmental pressures.

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Dr Adequate
Member (Idle past 362 days)
Posts: 16113
Joined: 07-20-2006


Message 190 of 223 (333772)
07-20-2006 3:46 PM


for me a "transitional fossil" is a fossil that's part say fish and part frog.
How much fish and how much frog? Along that line of development we have such varying delights as Achoania, Osteolepis, Styloichthys, Eusthenopteron, Panderichthys, Crassigyrinus, Tiktaalik, Ichthyostega, Acanthostega, and Triadobachtratus. Take your pick.
Edited by Dr Adequate, : To make it prettier.

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AdminJar
Inactive Member


Message 191 of 223 (333781)
07-20-2006 4:20 PM
Reply to: Message 190 by Dr Adequate
07-20-2006 3:46 PM


Welcome to EvC
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Again, welcome!

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    Chuteleach
    Inactive Member


    Message 192 of 223 (341043)
    08-18-2006 10:19 AM
    Reply to: Message 1 by Alasdair
    03-02-2006 12:55 PM


    never mind
    Edited by Chuteleach, : I see someone already said what i was going to. (fossils being alive)

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    Chuteleach
    Inactive Member


    Message 193 of 223 (341044)
    08-18-2006 10:31 AM
    Reply to: Message 189 by NosyNed
    07-19-2006 9:46 PM


    Re: That which has not evolved.
    Ok, how would a creature that lived several million years ago have no random genetic changes?

    This message is a reply to:
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    Percy
    Member
    Posts: 22606
    From: New Hampshire
    Joined: 12-23-2000
    Member Rating: 4.9


    Message 194 of 223 (341051)
    08-18-2006 10:45 AM
    Reply to: Message 193 by Chuteleach
    08-18-2006 10:31 AM


    Re: That which has not evolved.
    Chuteleach writes:
    Ok, how would a creature that lived several million years ago have no random genetic changes?
    You're asking about the Coelacanth? Coelacanth is an order, not a species. The species that survives today is not the same one as any of the fossil species that have been discovered. While we have no DNA from the extinct Coelacanths, since they aren't even the same species there must be a huge number of random genetic differences with the modern species.
    --Percy

    This message is a reply to:
     Message 193 by Chuteleach, posted 08-18-2006 10:31 AM Chuteleach has replied

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    Wounded King
    Member (Idle past 110 days)
    Posts: 4149
    From: Cincinnati, Ohio, USA
    Joined: 04-09-2003


    Message 195 of 223 (341053)
    08-18-2006 10:51 AM
    Reply to: Message 193 by Chuteleach
    08-18-2006 10:31 AM


    Re: That which has not evolved.
    Ok, how would a creature that lived several million years ago have no random genetic changes?
    Without DNA from fossilised coelacanths there is absolutely no reason to believe this is true. The fact that the extant living coelacanth is morphologically distinct from fossil coelacanths would suggest that this would not be true if we did find fossilised DNA. Indeed the different populations of modern coleacanth having a number of genetic changess between the populations givng the lie to the idea that no change has occurred (Holder et al, 1999).
    TTFN,
    WK

    This message is a reply to:
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