All species are transitional

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I always considered a transitional to be a direct link between two species.

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Scientists consider archeaopteryx to be a transitional species between modern birds and theropod dinosaurs. No scientist considers archaeopteryx to be an ancestral species to modern birds. Is this consistent with your concept of "transitional"?

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At some point in time there were probably 100's or 1,000's of species that were all cousins and all part way along the path from dinosaur to bird.

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So what is the current supra transitional sequence between all of them at the moment then? According to what is known?

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Scientists consider archeaopteryx to be a transitional species between modern birds and theropod dinosaurs. No scientist considers archaeopteryx to be an ancestral species to modern birds. Is this consistent with your concept of "transitional"?

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I'd say they are using a very loose definition of transitional species. Transition means to change from one form to another. So if archeaopteryx wasn't a species in the lineage going from a species of theropod dinosaur to modern birds, it wasn't a transitional species between the two. It may be an offshoot of a transitional.I think there is a difference between showing characteristics between two groups and being a transitional between two groups. The former would blur the distinction between groups, maybe even showing the dichotomy wasn't warrented. The latter would show they are related by a descent-ancestor relation.

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Transition means to change from one form to another.

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Yes, in everyday English that is exactly what "transition" means. And since archaeopteryx helps us in understanding the transition from theropod dinosaur to modern bird, the label "transitional fossil" is quite appropriate.Now I have another question. No fossil species are known to be in a direct ancestor/descendent link to any other species. Therefore, according to your definition, there are no transitionals known. Therefore, we have no examples of transitionals. So the word transitional is a word that applies to nothing. Does this square with your understanding?

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"Intellectually, scientifically, even artistically, fundamentalism -- biblical literalism -- is a road to nowhere, because it insists on fidelity to revealed truths that are not true." -- Katha Pollitt

Well, nothing is certain in science. So I would say there no transitional fossils "known".We hypothesize that there should be a transitional between two species, and we find likely canidates for this transitional.There is much utility in defining transitionals the way you do. The creatures you are referring to show there are no "kinds" in nature. But should be redefine what "transition" means in order to say we "know" there are transitionals?But if I'm looking for the evolutionary link (a transitional) between therapsids and placentals, and you show me a platypus I'd be a little incredulous.Also, i've had this discussion with my Evo professor so I know I'm in the "wrong" compared to the scientific consensus. In the end it's just semantics. It makes more sense, to me, to define transitional the way I did.

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There is much utility in defining transitionals the way you do.

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Which is why scientists use that definition. Definitions in any scientific field are made so as to be useful. The goal of much of evolutionary biology is to determine the lineages of known species, and perhaps the causes and constraints of those evolutionary changes. The only species that scientists have to work with are the known species, either the extant species or those known in the fossil record. Species like archaeopteryx give a large amount of insight into the evolution of birds, so fossils like archaeopteryx are special. This quality of being special is termed "transitional". You might not like it, but that is the way it is. One could use "transitional" to mean a direct ancestor/descendent link, but since we cannot identify actual ancestors with any degree of confidence, this definition would not be very useful to a scientist.-

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In the end it's just semantics.

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The purpose of have precise definitions in science is to avoid semantics issues. When laypersons insist on making up words or using their own definitions, they are creating semantics issues that scientists would prefer to avoid.

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"Intellectually, scientifically, even artistically, fundamentalism -- biblical literalism -- is a road to nowhere, because it insists on fidelity to revealed truths that are not true." -- Katha Pollitt

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The purpose of have precise definitions in science is to avoid semantics issues. When laypersons insist on making up words or using their own definitions, they are creating semantics issues that scientists would prefer to avoid.

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The thing is I'm not making up my own definition. That is what transitional means to 99% of the public.When a layperson hears that there is a transitional between two species, they think there is an evolutionary link. This is what creationists think the word means, and I think this causes much confusion when debating them. When a creationist says there are no transitional fossils, aren't they just saying there are no missing links? And isn't it disingenuous to tell them we have have transitionals when we are using a different definition than them?It seems absurd to say there is a transitional species between chimpanzees and humans since we are contemporaries known not to be in an ancestor-descendent relationship. Doesn't your definition basically say there are transitionals between any two species we pick? What is the utility in that?And interestingly enough, I never heard my professor once use the word transitional. Nor is it found anywhere in my text book, Evolution by Mark Ridley. Is it even used within formal evolutionary biology?

I just looked through "What Evolution Is" by Mayr, and he also doesn't mention transitional species. At best, he mentions "missing links showing the transition between two taxon" or something to that effect.

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The thing is I'm not making up my own definition. That is what transitional means to 99% of the public.

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If people can't be bothered to learn what the experts mean when they use a particular word, then who is to blame for the confusion?

I, personally, have never heard an expert use the word.I've read a couple of Evo textbooks as well. They mention missing links forming transitions between two species. That is the closest I have seen, and it uses transition in normal sense.

I just read a little bit of the FAQ of transitionals from Talk Origins.Here's what they have to say: I'll concede that it is too stringent a definition to say that a transitional must be directly ancestral.But the main problem I have with your definition is that it doesn't take time into account. Notice TalkOrigins says:

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The major point of these general lineages is that animals with intermediate morphology existed at the appropriate times, and thus that the transitions from the proposed ancestors are fully plausible.

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It just doesn't make sense to call the platypus a transitional species since there is no evidence of it existing during the therapsid (cynodont specifically)-mammal transition period (i.e., before 245 million years ago).

I have thought that I can find that the decrease in the use of the word "transitional" occurs with how much influence Simpson's "Classification of the Mammals" has on one's thought about monophyly. There is a dispute about how much Hennig might have taken without citation from Criozat. I have never tried to verify if that suspicion of mine is correct. Croizat derides Simpson's use taxonomy and draws teats out of the shape of Australia or therebouts, but that is not a likely response to this text. Mayr however insists that Rosa's Hologenesis is extinct in biology. It was not in the early 80s (I mean, I was not an effectively dead biologist then) nor in certain smaller publications to date. Therefore I tend to listen to creationists than figureing out how to cut up every Simopsonian univocal into a diversity of decontructive approaches to forms.Ref-
Scroll down to "classification"This message has been edited by Brad McFall, 10-06-2005 07:24 AM

Hypothetically,how would the discovery of a H.Sapien in a much earlier period, say in Australopithecus afarensis period between 3 and 4 million years ago, how would that impact our current evolution paradigm. This is not a creationist trick question. I'm honestly just curious?thank you

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And isn't it disingenuous to tell them we have have transitionals when we are using a different definition than them?

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No, since almost everything I have read about "transitionals" written for the layperson explains what a transitional is.

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No, since almost everything I have read about "transitionals" written for the layperson explains what a transitional is.

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I'd assume that the TalkOrigins site is written for the layperson, and they use "transitional" as synonomous with "possible missing link", which is much closer to the definition I gave than yours.I have yet to see a site that gives a definition so broad that the platypus is considered a transitional.This message has been edited by JustinC, 10-06-2005 11:33 AM