On Transitional Species (SUMMATION MESSAGES ONLY)

Do you have an example of an organism that doesn't fit this criteria?Every species has traits from a pre-existing species and the species after it will have traits from it too so.... Lets take a look. I don't mean to imply that those species are closely related or anything.But just looking at their form, the hippo, sea lion, and manatee all look like steps along the path from land mammal to sea mammal.Could we count those as transitionals? Like my examples above?Edited by Catholic Scientist, : No reason given.

What was kind-of the point!?My post was interrogative... Do I have to wait another coupla years for a reply?

You're weird... I guess the most confusing part, then, is why you posted this:

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I think the answer is:

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1. Not every organism can be considered an example of a 'Transitional Species'.

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Oh, okay, I think I understand what you are saying now. But, I do think you're wrong.You're using the word "transitional" in a colloquial sense, but there is an accepted usage of the word "transitional" by evolutionary biologists when referring to specific species and how they relate within the evolutionary lines. I think you'd be more accurate to use the word "intermediate". I agree with you on dead-ends but not on extinctions. Tiktaalik is a transitional that is extinct. Could be, I suppose, but should be I do not. The better word here would be "intermediate".

From wiki:

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The terms 'transitional' and 'intermediate' are for the most part used as synonyms; however, a distinction between the two can be made:

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"Transitional" can be used for those forms that do not have a significant number of unique derived traits that the derived relative does not possess as well. In other words, a transitional organism is morphologically close to the actual common ancestor it shares with its more derived relative.

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"Intermediate" can be used for those forms that do have a large number of uniquely derived traits not connected to its derived relative.
According to this definition, Archaeopteryx, which does not show any derived traits that more derived birds do not possess as well, is transitional. In contrast, the platypus is intermediate because it retains certain reptilian traits no longer found in modern mammals and also possesses derived traits of a highly specialized aquatic animal.

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Following this definition, all living organisms are in fact to be regarded as intermediate forms when they are compared to some other related life-form. Indeed there are many species alive today that can be considered to be transitional between two or more groups.

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My link did have this to say:

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Transitional vs ancestral

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A source of confusion is the concept that a transitional form between two different taxonomic group must be directly ancestral to one or both groups. This was exacerbated by the fact that one of the goals of evolutionary taxonomy was the attempt to identify taxa that were ancestral to other taxa. However, it is almost impossible to be sure that any form represented in the record is actually a direct ancestor of any other. In fact because evolution is a branching process that produces a complex bush pattern of related species rather than a linear process that produces a ladder like progression, and because of the incompleteness the fossil record, it is unlikely that any particular form represented in the fossil record is a direct ancestor of any other. Cladistics deemphasized the concept of one taxonmic group being an ancestor of another, and instead emphasizes the concept of identifying sister taxa that share a common ancestor with one another more recently than they do with other groups. There are a few exceptional cases, such as some marine plankton micro-fossils, where the fossil record is complete enough to suggest with confidence that certain fossils represent a population that was actually ancestral to another later population, but in general transitional fossils are considered to have features that illustrate the transitional anatomical features of actual common ancestors of different taxa rather than to be actual ancestors.

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Is the "distance" even really a focus of the determination of a transitional or not?I'm under the impression that its about forms and whether they have been uniquely derived or not.Take a hypothetical transition from a fish fin to a foot. Changes to the shape of the fin would be intermediates until it has enough uniquely derived traits that it can be considered a foot and then those species with that proto-foot are the transitional ones. The earlier ones where the shape was just changing are intermediates that don't really count as transitionals.Amirite?

I'm just trying to figure out the proper usage of the word but you seem to be focused on something else and its confusing me so I'm just gonna say thanks and stop pursuing this.So... Thanks.

Well I'm not gonna not reply I realize that's just an idiomatic phrase, but I would say that they are not the same for all purposes. Specifically, the purpose of studying evolutionary biology and the relationships between species that are or are not consider in a transition from one morphological feature to another.Further, there are distinctions between the terms used in that purpose that are important enough to maintain and not "grey out", so to speak. I agree that you can do this, but I don't find it particularly useful. Plus, I don't think the distinction is based solely on distance from the ancestor but also includes the morphologies, themselves. When I realized you had a different aim here than me, and that we're not really in much disagreement, is when I figured it wasn't worth pursuing any further. But there does seem to be enough disagreement to keep typing to you. It does, and I don't disagree with that. But I do think there is enough distinction between intermediate and transitional to keep them as seperately defined, at least for some purposes. That's what I was trying to exemplify with the 'fin-to-foot' hypothetical.

You're welcome

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Dead-ends/extinctions are not transitional ... so not every organism can be considered to be involved in transitional species.

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However, all extant species could be considered transitional except that we don't know into what yet.

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