A Note on the Transition from Fish to Tetrapods
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That is a big OOOPS for my evotard opponents...
"In a nutshell, the 'fish–tetrapod transition' usually refers to the origin, from their fishy ancestors, of creatures with four legs bearing digits (fingers and toes), and with joints that permit the animals to walk on land. This event took place between about 385 and 360 million years ago toward the end of the period of time known as the Devonian. The Devonian is often referred to as the 'Age of Fishes,' as fish form the bulk of the vertebrate fossil record for this time."- Jennifer Clack, The Fish–Tetrapod Transition: New Fossils and Interpretations; "Evolution: Education and Outreach", 2009, Volume 2, Number 2, Pages 213-223
That is a big OOOPS for my evotard opponents...
posted by Joe G @ 8:51 AM
27 Comments:
At 11:40 AM,
Zachriel said…
"When the facts change, I change my mind -- what do you do, sir?"
At 12:15 PM,
Joe G said…
The facts changed yet evotards haven't changed their minds.
Go figure...
At 3:19 PM,
Zachriel said…
Sure they have. The time of divergence was pushed back a bit.
At 4:29 PM,
Joe G said…
No, they haven't as evidenced by the evotard comments to my recent blogs- your comments included.
The time of divergence has been pushed back to "we have no idea".
You don't know when. You don't know where. You don't know why. And you don't know how nor even if.
Strange how the less we know the better your position looks.
At 5:45 PM,
Zachriel said…
Your confusing a transition, which is an event in time, with a transitional, which exhibits intermediate characteristics.
At 6:46 PM,
Joe G said…
The confusion is all Dr Clack's then...
At 6:51 PM,
Joe G said…
Fish-> tetrapod-> fishapod
Perhaps Tiktaalik was a transitional from tetrapods to fish...
At 9:54 PM,
Zachriel said…
Maybe this will help. It's a cladogram of the transition in question.
http://evolution.berkeley.edu/evolibrary/images/news/tiktaalik_phylogeny.gif
Notice that Tiktaalik is not ancestral to tetrapods, but a cousin, or sidebranch. Fishapods could conceivably live long past the point of divergence. They could even be around today, but apparently not. That means when looking for fossils, you could find fishapods after the first tetrapods. What scientists would like to find is a more ancient tetrapod. At this point, for the oldest tetrapods, they only have trackways.
At 7:03 AM,
Joe G said…
Zacho:
Maybe this will help.
Nope- we still have:
fish-> tetrapods-> fishapods
Zacho:
At this point, for the oldest tetrapods, they only have trackways.
So what? A tetrapod made those trackways.
At 7:04 AM,
Joe G said…
Zacho:
It's a cladogram of the transition in question.
Too bad no one knows if it is accurate.
At 7:24 AM,
Joe G said…
Face it Zacho- a transitional boils down to noithing more than "It looks like a transitional to me."
At 9:58 AM,
Zachriel said…
Zachriel: It's a cladogram of the transition in question.
Joe G: Too bad no one knows if it is accurate.
The issue concerns your misunderstanding of the posited relationship between the organisms.
http://evolution.berkeley.edu/evolibrary/images/news/tiktaalik_phylogeny.gif
Notice that Tiktaalik is not posited to be ancestral to tetrapods, but a cousin, or sidebranch. Though, the first actual fishapod is posited to exist before the first tetrapod, the fossils are not the first of either lineage. The earliest fossil fishapod can certainly appear after the earliest trackway for tetrapods.
At 11:20 AM,
Joe G said…
Zacho:
The issue concerns your misunderstanding of the posited relationship between the organisms.
You mean your false accusation that I have a misunderstanding.
Zacho:
Notice that Tiktaalik is not posited to be ancestral to tetrapods, but a cousin, or sidebranch.
Notice that is irrelevant to any claim i have made.
Zacho:
Though, the first actual fishapod is posited to exist before the first tetrapod,...
True but there still isn't any evidence to support that claim.
Zacho:
The earliest fossil fishapod can certainly appear after the earliest trackway for tetrapods.
Right but that can also be evidence that the first tetrapods evolved back into fish.
At 11:20 AM,
Joe G said…
Face it Zacho- a transitional boils down to noithing more than "It looks like a transitional to me."
At 8:22 AM,
CBD said…
Joe,
How would you define transitional and how would you know when one was found?
At 10:20 AM,
Joe G said…
Fish-> tetrapod-> fishapod
I sure as hell wouldn't define a fishapod as a transitional given that data...
At 11:51 AM,
CBD said…
Joe,
I sure as hell wouldn't define a fishapod as a transitional given that data...
So now we know how you would not define a transitional, how would you define a transitional?
At 4:06 PM,
Joe G said…
Well START with the main word- TRANSITION:
a : passage from one state, stage, subject, or place to another : change
b : a movement, development, or evolution from one form, stage, or style to another
So a transitionAL something that is in the process of changing/ evolving from one form to another.
Can't tell by fossils- you would need genetics.
At 1:05 PM,
CBD said…
Joe,
Can't tell by fossils- you would need genetics.
Untrue.
I find a fossil of a fish at time X.
I find a fossil of a mammal a time Y.
I look between those two times and find a fossil of a transitional form between those two forms.
I have found a transitional.
At 4:14 PM,
Joe G said…
Right, because to you "it looks like a transitional" is evidence enough.
At 4:22 PM,
Joe G said…
How can you then test your claim that the fossil you found is indeed a transitional?
At 5:04 PM,
CBD said…
Joe,
How can you then test your claim that the fossil you found is indeed a transitional?
We look at the fossils that surround it in time.
What else?
At 6:55 PM,
Joe G said…
So it's all subjective then. Got it.
At 12:22 PM,
CBD said…
Joe,
So it's all subjective then.
How can it be subjective if it depends on what specifically surrounds the fossil in time?
At 4:15 PM,
Joe G said…
OM:
How can it be subjective if it depends on what specifically surrounds the fossil in time?
Because there isn't any way to objectively verify it is/ was a transitional.
You are stuck on "it looks like a transitional to me".
At 3:55 PM,
CBD said…
Joe,
Because there isn't any way to objectively verify it is/ was a transitional.
Well, if you find B in between A and C and B is a blend of A and C with some characteristics of both then what is B if it's not a transitional form between A and C? And what is C if not a transitional between B and D?
And that's essentially what we find.
A fish with wrists!
So you are right. The only way we can know is "it looks like a transitional to me" because experts spend years of their life learning about the subject. And they can say that. And it looks like a transitional to them.
And who am I going to believe, you or them?
At 6:15 PM,
Joe G said…
OM:
Well, if you find B in between A and C and B is a blend of A and C with some characteristics of both then what is B if it's not a transitional form between A and C? And what is C if not a transitional between B and D?
And that's essentially what we find.
Liar. Tiktaalik was found in strata dating to after tetrapods roamed the earth. So B was not found in between A and C, moron.
The evidence STILL says:
fish-> tetrapods-> fishapod
But thanks for confirming that saying "it looks designed" is scientific because experts have spent many years of their lives collecting data and knowledge on cause and effect relationships.
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