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Author Topic:   The Definition and Description of a "Transitional"
jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 76 of 110 (165700)
12-06-2004 4:01 PM
Reply to: Message 72 by Itachi Uchiha
12-06-2004 12:55 PM


Re: Trying to head back towards the topic...
Apparently there are as many definitions for evolution as there are minds. For some people evolution is getting better and better for others its just survival of the fittest. For some everything started with the big bang and for others the big bang has nothing to do with evolution. Who am I gonna believe? Heres a quote from David Menton PhD. He is a researcher for AiG.
Believe jazzlover.
Let's really look at that list because there are actually three subjects there and if we are to make any progress towards defining a transitional we need to get some of them out of there.
First, there is the existence of the universe. That is the field of Cosmology and has nothing to do with whether or not any life ever evolved. The Big Bang is one of the theories involved in Cosmology.
Second is the origin of life. It is mostly a question of chemistry.
Finally, there is evolution. It deals with what happened with life after it started, but it doesn't address or care how life started. Life may well have started through natural processes or by divine intervention. Regardless, once life started it changed over time. That is the area of Evolution.
The folk at AIG and ICR love to try to blur the three, but they are simply wrong. The three are different, seperate and totally unrelated.
Are you seeing the flaws in logic of your theory.
Nope. All I see is an attempt to confuse folk. Almost nothing in the long quote is true or even has anything to do with evolution or transitionals.
There are many examples of convergent development. Often it is driven by the environment, sharks and whales have similar shapes but they most definitely developed independantly.
So I asked, "So back towards the topic, you find two skeletons. How do you identify whether they are humans or chimps?"
to which you replied:
Are talking about complete skeletons or a part of a skeleton. if it is a part mention which part.
For now, let's assume that we have complete skeletons.

Aslan is not a Tame Lion

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Anti-Climacus
Inactive Member


Message 77 of 110 (165997)
12-07-2004 6:23 PM


Maybe I can help contribute to this discussion.
Mark24 (evolutionist): A transitional is a form that possesses character states that are part way between two separate taxa, &/or a mix of discrete characters between two taxa.
Reply: If we define transitional in this way, then there is truly no organism on the planet (extant or extinct) that could not be considered a transitional, because every organism, no matter how exotic, will have characteristics that are in some way similar to organisms of other taxa. We will simply end up with Darwin Redux’s perspective that every organism that has ever existed (including us) is a transitional form. A definition that explains everything is really no definition at all.
Robert Byers (creationist): We Don't believe there are transitionals so our defining what they are or look like is, ah, unnatural.
Reply: I think you are overlooking some key points. As a creationist myself, I accept that transitionals did and do exist. The limited number of animals on the Ark subsequently evolved into many of the land animals we see today. Most creationists, whether they know it or not, seem to take this perspective. It would seem that the difference between creation and evolution does not lie in whether or not transitionals existed to bridge organisms to common ancestors. On the contrary, the fundamental difference is that creationists: (a) deny that transitionals linked all major animals groups to a single common ancestor (i.e., they instead propose the existence of numerous common ancestors in the form of kinds); and (b) deny that the stratigraphical sequences of fossils in the geologic record are attributable to evolutionary change (i.e., they propose that the fossil record is the result of non-evolutionary mechanisms).
Loudmouth (evolutionist): Creationists claim that that evolutionists have not FOUND any transitional fossils . . . Creationist claim that it isn't transitional because it doesn’t jive with their Bible, a very subjective and empty reason. Instead of giving concrete, objective reasons for rejecting these fossils, creationists instead claim that they SHOULDN'T exist, which, I guess, allows them to ignore their very existence. IOW, creationists are scared so they refuse to look at them or define what a transitional fossil should look like.
Reply: Very true. There are many on my side of the debate that refuse to perform research for the reasons you cited. I really see no point in being scared of the facts.
Jazz writes: Incredibly, evolutionists explain away amazing similarities between animals they consider to be only distantly related by simply invoking "convergent evolution." Convergent evolution is the unobserved and unexplained process whereby two very different animals independently evolve into two very similar animals by an incredible run of countless lucky mutational coincidences extending over tens of millions of years! It seems that some folks will believe almost anything, as long as it doesn't appear in the Bible.
PaulK then responds: For instance dolphins icthyosaurs and sharks share a similar overall form because of the way they live. Convergent evolution is often largely the result of functional constraints - and often the results can be seen to be quite distinct. Convergent evolution is certainly not unexplained and it is clearly evidenced.
Reply: I would have to agree with Jazz here. One can pick up any comprehensive paleontology resource to grasp the frequency of alleged evolutionary convergence. For example, Robert L. Carroll’s Vertebrate Paleontology and Evolution and Barbara Stahl’s Vertebrate History: Problems in Evolution cite over 110 examples on the following pages respectively:
quote:
p. 7, 8, 22, 24, 27, 35, 44-45, 54, 74, 88-89, 109, 118, 120, 133, 143, 146-147, 151, 159, 182, 182, 198, 199, 221, 222, 225, 225, 254, 265, 268-269, 276, 282, 289-290, 331, 332, 345, 347, 348, 351, 373, 389, 421, 421, 451, 452, 454, 457, 461, 468, 473-474, 477-478, 478, 483, 484, 492, 513, 516, 517, 518, 519, 523, 525, 531, 532, 547, 552-553, 560
quote:
p. 87, 109, 135, 141-142, 151, 153, 153-154, 157, 158, 161, 164, 180, 188, 190, 221, 221-222, 223-224, 225, 227-228, 234, 235-236, 240-241, 242, 248, 265, 273, 275, 276, 283, 286, 293, 324, 349, 358, 373, 439, 461-462, 486, 490-491, 492, 533, 536
Among all of these quotes is the following:
quote:
In contrast, biologists working with both modern and extinct groups argue that convergence is very common (Cain 1982; Carroll 1982). Arguments for the close relationship of groups based only on the common presence of derived features are of little value, if convergence is equally or more common than the unique origin of derived characters. (Carroll, p. 9)
It soon becomes clear that modern evolutionary theorists have turned a massive set of seemingly contradictory data points into supporting evidence. And all of this falls quite nicely into any definition of transitional that we conjure up here. Those fossils that fit the definition support evolutionary theory, while those fossils that do not fit (or contradict) the definition can be explained away by convergence and therefore indirectly . . . support evolution. How convenient.
I am still unclear as to how to define transitional in such a way as to provide a possibility for falsification. There is also the possibility that the fossil record is incapable of distinguishing which organisms are truly transitionals and which are not. But if someone were to challenge me for a definition, I suppose I would offer the following:
quote:
A transitional fossil is that which contributes to the demonstration of a lineage of forms which gradually develop morphological/physiological characteristics.
In any case, whatever definition of transitional that modern evolutionary theorists have decided upon, they are less than shy in admitting their virtual non-existence (except to the general public, of course). A brief look at the evolutionary literature will make this point evident, as Carroll and Stahl (see above) in their paleontology books admitted the failure of the fossil record to demonstrate morphological/physiological change in 239 separate paragraphs.

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PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 78 of 110 (165999)
12-07-2004 6:45 PM
Reply to: Message 77 by Anti-Climacus
12-07-2004 6:23 PM


I notice that while you reject my comment you offer no clear refutation. Yet both my examples deal with clear examples of convergence. And if I can deal with 3 so simply who is to say that there is anything more problematic in your 110 ?
You don't offer any clear examples nor do you offer any clear statement as to the scale of the problem. If convergence turns out to be a problem in closely related species then it is no threat to our ideas of large-scale evolution. It simply obscures details - and casts no doubt over the general principle of common ancestry (an analagous case might be uncertainty over whether two branches of a family split ten generations ago or eleven). Yet where are the examples that offer evidence of convergence at a scale that would cause serious problems for evolutionary theory ? I think you need to offer far more detail to actually make the case that convergence is anything like the problem you claim that it is.
And it is certainly false to say that paleontologists have admitted the virtual non-existence of transitional forms. The lack is purely at the level of speciation - which you believe in. The paleontologist usually quoted by creationists on this matter is Stepehen Jay Gould - and he claimed that at higher taxonomic levels transitional fossils were abundant.

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Anti-Climacus
Inactive Member


Message 79 of 110 (166033)
12-07-2004 9:47 PM


I do not want to get too far off topic, so I’ll be brief.
PaulK: Yet where are the examples that offer evidence of convergence at a scale that would cause serious problems for evolutionary theory?
Reply: The concept of convergence is most definitely a problem for evolution via random mutations, simply because of the very fact that all of these instances of parallel evolution must have had fortuitously similar mutations occurring independently from one another. And since mutation is random, the development of major morphological/physiological characteristics multiple times is not what one would expect.
You also stated in an earlier post that, convergence typically produces similarities that are seen to be "skin deep" when examined in more detail. But this is not true. There are a multitude of highly specialized structures that appear abruptly in species not closely related. For example:
quote:
The Cypriniformes differ from most teleosts in having the majority of their species specialized as herbivores. The marginal teeth are lost, but the pharyngeal jaws form an effective grinding and crushing apparatus. They have a highly specialized mechanism that protrudes the jaws, as do the spiny teleosts, but it evolved separately in the two groups (Alexander). (Carroll, p. 120)
Certainly not skin deep.
PaulK: And it is certainly false to say that paleontologists have admitted the virtual non-existence of transitional forms. The lack is purely at the level of speciation - which you believe in. The paleontologist usually quoted by creationists on this matter is Stephen Jay Gould - and he claimed that at higher taxonomic levels transitional fossils were abundant.
Reply: I find these statements to be illogical. The only possible way to bridge higher taxonomic levels is with lineages of individual forms! If the individual forms are missing, there is no way to bridge the higher taxonomic levels.
Edit: I am still especially interested in obtaining a definition of "transitional" that allows the possibility of anomalies (to safely escape the logical fallacy of a Self-Fulfilling prophecy).
This message has been edited by Anti-Climacus, 12-07-2004 09:48 PM

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Buzsaw
Inactive Member


Message 80 of 110 (166079)
12-08-2004 12:54 AM
Reply to: Message 79 by Anti-Climacus
12-07-2004 9:47 PM


Welcome, Anti-Climacus!
Thanks for bringing some needed balance here in our science department. Your articulate style and knowledge which some of us creationists don't posess in the science field is indeed refreshing. I hope you will take up long term residence here in town
This message has been edited by buzsaw, 12-08-2004 12:56 AM

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crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 81 of 110 (166089)
12-08-2004 1:44 AM
Reply to: Message 79 by Anti-Climacus
12-07-2004 9:47 PM


The only possible way to bridge higher taxonomic levels is with lineages of individual forms! If the individual forms are missing, there is no way to bridge the higher taxonomic levels.
How so?

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PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 82 of 110 (166097)
12-08-2004 2:18 AM
Reply to: Message 79 by Anti-Climacus
12-07-2004 9:47 PM


Of course similar mutations are not necessarily a problem. Remember that we are generally talking about similarities in the phenotype, and ones that have functional advantages that are difficult to obtain in other ways. Your argument manages to ignore the role of selection and as such is clearly invalid.
Your example of the spiny teleosts and the Cypriniformes does not show that my state,ment is false - that is a logical error. Since my statement expressly allows for exceptions you need a large number of examples to refute it - and you do not even go into enough detail to be certain that your example is valid.
And of course there is no problem with transitional fossils above species level being relatively common compared to transitionals between species. It is even a prediction of Punctuated Equilibria. Punctuated Equilibria states that species tend to last a considerable time (even in geologial terms), yet transitions between species are take place in very small populations that are geographically localised over a geologically brief period of time (mere thousands of years). So it is not surprising that we should find fossils of species representing transitions between higher taxonomic ranks while intermediates between species should be rare.
Moreover we should remember that it is the transitions between higher taxonomic levels that are most problematic to creationism. Creationism can accept limited evolution between similar species. However we have transitionals representing larger scale evolutionary steps that creationists deny. Evolutionary theory states that these should exist - therefore the fact that they do is significant evidence for evolution which predicts that they would exist and creationism in which they are at best unexpected.

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mark24
Member (Idle past 5195 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 83 of 110 (166135)
12-08-2004 5:12 AM
Reply to: Message 77 by Anti-Climacus
12-07-2004 6:23 PM


Anti-Climacus,
Mark24 (evolutionist): A transitional is a form that possesses character states that are part way between two separate taxa, &/or a mix of discrete characters between two taxa.
Reply: If we define transitional in this way, then there is truly no organism on the planet (extant or extinct) that could not be considered a transitional, because every organism, no matter how exotic, will have characteristics that are in some way similar to organisms of other taxa. We will simply end up with Darwin Redux’s perspective that every organism that has ever existed (including us) is a transitional form. A definition that explains everything is really no definition at all.
Not true, the context for the definition is 1/cladistic, & 2/ pertains to the fossil record. So any given fossil can only be considered transitional if it occurs below the crown group of any given taxon in a cladogram/phygenetic tree. Putting it simply, if something contains reptilian & bird characters (& those characters by definition do not show homoplasy), then it is representative of a transitional form between those two taxa, & is indicative that a cladogenetic event occurred.
Mark
This message has been edited by mark24, 12-08-2004 05:17 AM

There are 10 kinds of people in this world; those that understand binary, & those that don't

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Mammuthus
Member (Idle past 6475 days)
Posts: 3085
From: Munich, Germany
Joined: 08-09-2002


Message 84 of 110 (166139)
12-08-2004 5:44 AM
Reply to: Message 81 by crashfrog
12-08-2004 1:44 AM


If I understand him correctly, if I know who my great grandfather is (because I have access to his bones) but do not know who my grandfather was because there is no body remaining, I cannot be related to my great grandfather. This is a typical creationist argument against transitionals...if you don't have a fossil for every individual that ever lived, they claim evolution cannot have happened.

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Quetzal
Member (Idle past 5872 days)
Posts: 3228
Joined: 01-09-2002


Message 85 of 110 (166198)
12-08-2004 10:04 AM
Reply to: Message 79 by Anti-Climacus
12-07-2004 9:47 PM


Hi AC: Welcome to the forum. It's a pleasure to see postings by a creationist who isn't simply either hit-and-run or who merely wishes to "witness" to the heathen.
Reply: The concept of convergence is most definitely a problem for evolution via random mutations, simply because of the very fact that all of these instances of parallel evolution must have had fortuitously similar mutations occurring independently from one another. And since mutation is random, the development of major morphological/physiological characteristics multiple times is not what one would expect.
You also stated in an earlier post that, convergence typically produces similarities that are seen to be "skin deep" when examined in more detail. But this is not true. There are a multitude of highly specialized structures that appear abruptly in species not closely related. For example:
quote:
The Cypriniformes differ from most teleosts in having the majority of their species specialized as herbivores. The marginal teeth are lost, but the pharyngeal jaws form an effective grinding and crushing apparatus. They have a highly specialized mechanism that protrudes the jaws, as do the spiny teleosts, but it evolved separately in the two groups (Alexander). (Carroll, p. 120)
Certainly not skin deep.
On the contrary, the form of homoplasy known as convergent evolution is, in fact, "skin deep". Functional morphological features that are superficially similar, as for example the eye of vertebrates and cephalopods (both have a lens and retina), quite clearly arose through completely different developmental pathways. IOW, they evolved independently. On page 111 of Futuyma's "Evolutionary Biology", there is an excellent diagram and explanation showing clearly that the differences in even such superficially nearly identical features as these two types of eye far outweigh their similarities - even tho' they serve a similar purpose for the organism. A few examples: retinal axons arise from the cell bases in cephalopods, but the cell apices in vertebrates; vertebrate nerve fibers run across the surface of the retina and converge in the optic nerve, creating a "blind spot", those in cephalopods run directly "back" from the bases into the optic ganglia.
Even more striking convergent examples abound: one of my favorites is the similarity of form but completely different development of (totally unrelated) species in the Cactacae (cactus - US), Asclepiadaceae (milkweed - Africa), and Euphorbiaceae (splurge - Africa). The similarity of form is in response to extremely similar selection pressures in similar habitats. IOW, the plants are filling similar niches and subject to similar environmental stresses, so similar phenotypical adaptations - not the same adaptation, or even from the same kinds of mutations - are prevalent and expected under evolutionary theory.
Could you please explain how the passage you quoted supports your position? Specialized structures are an understood part of homoplasy. However, those specialized structures are not identical in cases of convergent (or for that matter parallel) evolution - they are simply structures that because of environmental constraints are similar in function. The canines of Thylacinus and Canus lupus appear visually to be nearly identical, but they develop differently and are/were used in a completely different fashion.

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Ooook!
Member (Idle past 5815 days)
Posts: 340
From: London, UK
Joined: 09-29-2003


Message 86 of 110 (166200)
12-08-2004 10:06 AM
Reply to: Message 79 by Anti-Climacus
12-07-2004 9:47 PM


Hi,
I never really understood how creationists can have a problem with convergent evolution without ignoring the principle of selection and overlooking the shared developmental pathways of organisms. I'm not quite as knowledgeable in this area as Mammuthus and Mark24, but let me try to put my case forward.
  1. The power of a selective environment If two organisms are in the same environment, with the same selective pressures, then why shouldn't the same kind of structures be selected for? If a fin shape is advantageous for a shark, why not for a whale?
  2. Shared developmental pathways The underpinning principle of common descent is key when looking at convergent evolution. Evolution works with, and builds upon, what is already present . If two species share a common ancestor then they will undoubtably share some underlying developmental processses as well. Eyes are an excellent example of this: there are many different types of eye in the world, but it seems that they are all under the control of the same master control gene. Similary with your fishy example: why couldn't the same initial pharygeal 'arrangement' been co-opted from a shared ancestoral characteristic? I think there were once fish which had pharyngeal 'teeth' which are now extinct (I'll try and dig out the reference).
Taking that into account then (and trying to angle my argument vaguely towards the topic), discounting transitional fossils as simply abherrations of classification is not truly addressing the facts, and is misleading. It's all about looking at the whole picture, and looking at it carefully. Looking at the fins of whales and fish clearly shows that they are built differently, while there are similarities between whales and land mammals. Our eyes are fundamentally different to those of drosophila, but are similar to other mammals. Exactly how indentical are the "highly specialized mechanism[s]" of spiny teleosts and Cypriniformes? How fundamentally different are these structures from other teleost fish?

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Darwin Redux
Inactive Member


Message 87 of 110 (168272)
12-14-2004 8:57 PM
Reply to: Message 73 by AdminJazzlover
12-06-2004 1:01 PM


Re: Totally off topic
As a matter of fact I'm not a girl. Do you have a problem with that?

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Loudmouth
Inactive Member


Message 88 of 110 (168526)
12-15-2004 12:22 PM
Reply to: Message 77 by Anti-Climacus
12-07-2004 6:23 PM


quote:
If we define transitional in this way, then there is truly no organism on the planet (extant or extinct) that could not be considered a transitional, because every organism, no matter how exotic, will have characteristics that are in some way similar to organisms of other taxa.
This is false. It is true that every organism is a transitional, but this is because evolution is the best theory. A non-transitional would be a bat with feathers or a whale with gills. Not only does a transitional need to have characteristics that bridge two taxonomic groups, but that bridge must be along evolutionary lines. The fact that these types of transitionals (ie feathered bats and gilled whales) do not exist is a testament to the accuracy of the theory of evolution. What would prevent God from creating bats with feathers or whales with gills? Nothing. However, these orgaisms would falsify the theory of evolution.
quote:
I think you are overlooking some key points. As a creationist myself, I accept that transitionals did and do exist. The limited number of animals on the Ark subsequently evolved into many of the land animals we see today. Most creationists, whether they know it or not, seem to take this perspective. It would seem that the difference between creation and evolution does not lie in whether or not transitionals existed to bridge organisms to common ancestors. On the contrary, the fundamental difference is that creationists: (a) deny that transitionals linked all major animals groups to a single common ancestor (i.e., they instead propose the existence of numerous common ancestors in the form of kinds); and (b) deny that the stratigraphical sequences of fossils in the geologic record are attributable to evolutionary change (i.e., they propose that the fossil record is the result of non-evolutionary mechanisms).
In my opinion, the usual "litmus test" that creationists apply to the "created kinds" is a very simple one. Any amount of evolution judged to be capable of producing man from ape is considered false. The litmus test is really the ape-man test.
The reality of the matter is that we have very nice transitional fossils for the transition between reptile and mammal, land mammal and whale, ape-like ancestor and man, etc. The supposed small steps in evolution described by creationists are actually outnumbered by the larger number of fossils supporting larger changes.
quote:
It soon becomes clear that modern evolutionary theorists have turned a massive set of seemingly contradictory data points into supporting evidence. And all of this falls quite nicely into any definition of transitional that we conjure up here. Those fossils that fit the definition support evolutionary theory, while those fossils that do not fit (or contradict) the definition can be explained away by convergence and therefore indirectly . . . support evolution. How convenient.
This is totally false. You are forgetting about the examples I listed that could, in fact, falsify evolution. Feathered bats and gilled whales could not be explained through evolutionary theory given the fossil record that we have. What prevented God from creating such creatures? Nothing.
Also, you are forgetting about the second realm of evidence within evolution, DNA. Let's take a specific example. Are you familiar with the tasmanian wolf? It is a marsupial carnivore that, outwardly, closely resembles the north american wolf. According to the fossil record the NA wolf and the tasmanian wolf are examples of convergent evolution. Given that DNA reflects one's ancestory despite outward appearances, the tasmanian wolf should be distantly related to NA wolves and more closely related to other animals, such as kangaroos and wombats, on the mainland of Australia and Tasmania. Guess what the data says? The NA wolf is as closely related to the tasmanian wolf as they are to humans. The closest DNA match to tasmanian wolves are other marsupials, which look nothing like a wolf, in Australia and Tasmania. A tasmanian wolf, despite outward appearances, is more closely related to kangaroos than to the NA wolf. If a creator made all of these species separately we would expect, from outward appearances, the tasmanian and NA wolf would be the closest relatives. This is simply not true. Therefore, convergent evolution is both supported and logical.
quote:
I am still unclear as to how to define transitional in such a way as to provide a possibility for falsification.
Feathered bats and gilled whales are perfect examples of transitionals that would falsify evolution. For evolution to be true there must be a nested hierarchy. That is, each group of species must fit inside a larger description of a larger group. For instance, humans are part of the great apes. Great apes and monkeys fit into the larger group called primates. Primates and ungulates fit into a larger group called placental mammals. This is what is called a nested hierarchy where each group nests inside of a larger group.
A transitional that does not fit this pattern is a potential falsification of evolution. That is why a mammal sharing bird characteristics is a falsification. The fact that we don't see these types of transitionals is a testament to the accuracy of evolution, not it's inability to be falsified.
quote:
In any case, whatever definition of transitional that modern evolutionary theorists have decided upon, they are less than shy in admitting their virtual non-existence (except to the general public, of course). A brief look at the evolutionary literature will make this point evident, as Carroll and Stahl (see above) in their paleontology books admitted the failure of the fossil record to demonstrate morphological/physiological change in 239 separate paragraphs.
This glosses over the fact that we do have transitional fossils that bridge large gaps. While we may not have ALL of the transitional fossils, we do have enough to have great confidence in the theory of evolution. This is the very attitude that I was speaking of before, about creationists being afraid to face the facts. Creationists would rather talk about the gaps than fess up to the gaps that have been filled. Just one transitional fossil between two divergent taxa (ie mammals and reptiles) falsifies special creation. According to creationism, there should not be a string of transitionals that have both mammalian and reptillian characteristics. According to creationist, a feathered bat or a gilled whale should have the same chances of being created as a transitional between reptiles and mammals. Why don't we see feathered bats or gilled whales?

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dpardo
Inactive Member


Message 89 of 110 (168582)
12-15-2004 2:46 PM
Reply to: Message 88 by Loudmouth
12-15-2004 12:22 PM


Loudmouth writes:
The reality of the matter is that we have very nice transitional fossils for the transition between reptile and mammal, land mammal and whale, ape-like ancestor and man, etc.
Can you post a link to this/these "very nice" transitional fossil(s) for ape-like ancestor and man?

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Jazzns
Member (Idle past 3911 days)
Posts: 2657
From: A Better America
Joined: 07-23-2004


Message 90 of 110 (168613)
12-15-2004 3:33 PM
Reply to: Message 89 by dpardo
12-15-2004 2:46 PM



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