Transitional Fossils Show Evolution in Process

We often see complaints or comments about the absence of fossil evidence for transitions in evolution. This usually comes in two parts:(1) There are no transitional fossils PRATT CC200

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There are no transitional fossils. Evolution predicts a continuum between each fossil organism and its ancestors. ...

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Often this is due to a misunderstanding of what "transitional" means in evolutionary biology:Transitional fossil - Wikipedia

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Transitional fossils (popularly termed missing links) are the fossilized remains of intermediary forms of life that illustrate an evolutionary transition. They can be identified by their retention of certain primitive (plesiomorphic) traits in comparison with their more derived relatives, as they are defined in the study of cladistics. Numerous examples exist, including those of primates and early humans.

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According to modern evolutionary theory, all populations of organisms are in transition. Therefore, a "transitional form" is a human construct of a selected form that vividly represents a particular evolutionary stage, as recognized in hindsight. Contemporary "transitional" forms may be called "living fossils", but on a cladogram representing the historical divergences of life-forms, a "transitional fossil" will represent an organism near the point where individual lineages (clades) diverge.

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Thus all fossils that show intermediate characteristics between ancestral forms and descendant forms are by definition transitional. Thus whenever we see a clear lineage of fossils from an ancestral form (plesiomorphic) to derived descendant form (apomorphic), and thus they are transitional fossils.Transitional fossils will be intermediate in form between ancestral forms and descendant forms, and they will share some, but not all, traits with both ancestors and descendants, and some traits shared by ancestors, the transitional fossil and descendants may themselves be shown in intermediate stages of development, between the ancestral and descendant forms of the traits.(2) There should be billions of transitional fossils PRATT CC200.1

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Given all the species that exist and have existed, there should be billions of transitional fossils in the fossil record; we should have found tens of thousands at least.

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A recent example of this misunderstanding was presented by Kaichos Man on An ongoing report on S366:Evolution Message 19: This thread is intended to discuss and answer this issue.Enjoy.ps - I will also add 3 responses as subthreads, which will cover my initial response at Message 20, so please let me complete those before promotion.Edited by Admin, : Fix rendering.

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In the post that inspired this thread Kaichos Man claimed (Message 19): This, of course is the hoary old "absence of evidence is evidence of absence" logical fallacy.The complete absence of fossil evidence for the Coelacanth between the end of the Cretaceous period and modern day clearly proves that these fish did not exist between then and now ....Clearly this statement is false when the Coelacanths are living organisms in the modern world.Other logical fallacies are the argument from ignorance (there are no transitional fossils) and the argument from incredulity (we should be up to our necks in transitional fossils).Logical fallacies are invalid arguments.Enjoy.

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In the post that inspired this thread Kaichos Man claimed (Message 19): There are many examples of transitional fossils, and I will discuss two of these as they apply at the species level and they show precisely the "tiny dawinian step" involved in the process of speciation.(1) Foramiinifera: Evolution at Sea
Complete Fossil Record from the Ocean Upholds Darwins Gradualism

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Tony Arnold and Bill Parker compiled what may be the largest, most complete set of data on the evolutionary history of any group of organisms, marine or otherwise. The two scientists amassed something that their land-based colleagues only dreamed about: An intact fossil record with no missing links.

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"It's all here--a virtually complete evolutionary record," says Arnold. "There are other good examples, but this is by far the best. We're seeing the whole picture of how this group of organisms has changed throughout most of its existence on Earth."

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The organism that Arnold and Parker study is a single-celled, microscopic animal belonging to the Foraminiferida, an order of hard-shelled, planktonic marine protozoans. Often shortened to "forams," the name comes from the Latin word foramen, or "opening." The organisms can be likened to amoebas wearing shells, with perforations through which their protoplasm extends. The foram shell shapes range from plain to bizarre.
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"There's a nifty passage in Darwin," says Arnold, "in which he descirbes the fossil record as a library with only a few books, and each book has only a few chapters. The chapters have only a few words, and the words are missing letters."

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"Well, in this case, we've got a relatively complete library," says Arnold. "The 'books' are in excellent shape. You can see every page, every word."

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As he speaks, Arnold shows a series of microphotographs, depicting the evolutionary change wrought on a single foram species. "This is the same organism, as it existed through 500,000 years," he says. "We've got hundreds of examples like this, complete life and evolutionary histories for dozens of species."

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About 330 species of living and extinct planktonic forams have been classified so far. After thorough examinations of marine sediments collected from around the world, micropaleontologists now suspect these are just about all the free-floating forams that ever existed.

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The species collection also is exceptionally well-preserved, which accounts largely for the excitement shared by Parker and Arnold. "Most fossils, particularly those of the vertebrates, are fragmented--just odds and ends," says Parker. "But these fossils are almost perfectly preserved, despite being millions of years old."
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Darwin termed the process gradualism, a theory that invokes the slow accumulation of small evolutionary changes over a large period of time, as a result of the pressures of natural selection. What Arnold and Parker found is almost a textbook example of gradualism at work.

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We've literally seen hundreds of speciation events," syas Arnold. "This allows us to check for patterns, to determine what exactly is going on. We can quickly tell whether something is a recurring phenomenon--a pattern--or whether it's just an anomally. This way, we cannot only look for the same things that have been observed in living organisms, but we can see just how often these things really happen in the environment over an enormous period of time.

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Not just transitional fossils between one species to the next, but the whole pattern of this foraminifera phylum laid out in detail.(2) Pelycodus: A Smooth Fossil Transition: Pelycodus, a primate

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Pelycodus was a tree-dwelling primate that looked much like a modern lemur. The skull shown is probably 7.5 centimeters long.

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The numbers down the left hand side indicate the depth (in feet) at which each group of fossils was found. As is usual in geology, the diagram gives the data for the deepest (oldest) fossils at the bottom, and the upper (youngest) fossils at the top. The diagram covers about five million years.

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The numbers across the bottom are a measure of body size. Each horizontal line shows the range of sizes that were found at that depth. The dark part of each line shows the average value, and the standard deviation around the average.

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The dashed lines show the overall trend. The species at the bottom is Pelycodus ralstoni, but at the top we find two species, Notharctus nunienus and Notharctus venticolus. The two species later became even more distinct, and the descendants of nunienus are now labeled as genus Smilodectes instead of genus Notharctus.

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As you look from bottom to top, you will see that each group has some overlap with what came before. There are no major breaks or sudden jumps. And the form of the creatures was changing steadily.

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This fossil record clearly shows the "tiny dawinian steps" from generation to generation. Note that the "gaps" in time for the fossils are more than covered by the overlap in the variation within each level, each level has organisms similar to the ancestral population below it and to the descendant population above it.ConclusionClearly transitional fossils exist at the species level, fossils that clearly show the "tiny dawinian steps" from generation to generation.Enjoy.Edited by RAZD, : spling

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In the post that began this thread Kaichos Man claimed (Message 19): We can ascertain the veracity of this arguement from incredulity by comparing the fossil record for the Foraminifera, Pelycodus and the Coelacanth.As we see in the case of Foraminifera, transitional fossils between species (and higher) exist in abundance at all levels, and in this one case they cover millions of years in a continuous record. This is because the accumulation of these fossils in this location is not reliant on haphazard fossilization, random environmental factors or other things affecting the fossilization of individual organisms.Thus we see, that when there are no causes preventing the reservation of fossils, or for disrupting fossils after deposition, that there is indeed the well preserved record of evolving life year after year, generation after generation, species after species, etc etc, for millions of years.Next we look at Pelycodus and we do see gaps between the fossil layers. There are several reasons such gaps can exist:

• the organisms can migrate between areas and thus are only fossilized in one area when they die in that area,
• natural disasters that kill and cover organisms to begin the fossilization process may be relatively rare in the ecology, and
• the ecology may alternate between wet and dry, with fossils only being preserved during dry periods,
• etc.

Finally, we look at the Coelacanth. The last fossil evidence for Coelacanths is over 65 million years old:Coelacanth - Wikipedia

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Although now represented by only two known living species, as a group the coelacanths were once very successful with many genera and species that left an abundant fossil record from the Devonian to the end of the Cretaceous period, at which point they apparently suffered a nearly complete extinction. Before the living specimens were discovered, it was believed by some that the coelacanth was a "missing link" between the fish and the tetrapods. It is often claimed that the coelacanth has remained unchanged for millions of years, but, in fact, the living species and even genus are unknown from the fossil record. The most likely reason for the gap is the taxon having become extinct in shallow waters. Deep-water fossils are only rarely lifted to levels where paleontologists can recover them, making most deep-water taxa disappear from the fossil record.

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Here we have a gap in the fossil record of ~65 million years, and yet we have living Coelacanths that clearly show that the absence of fossil evidence is not evidence of absence of Coelacanths. This also shows that fossils do not have to be preserved for intermediate forms.ConclusionsWhat is clear, from comparing these three cases, is:

1. there is a significant difference in the degree of preservation of fossils between Foraminifera, Pelycodus and Coelacanths,
2. when there are no reasons for fossils not to be preserved (Foraminifera), that there are extensive fossil transitional records,
3. when there are reasons that fossils may not be preserved (Pelycodus), that there are gaps in the fossil record due to missing fossils, and
4. even when there are massive gaps in the fossil record (Coelacanths), that this does not mean that the intermediate organisms were missing, just that they did not fossilize where fossils have been discovered

Simply put, fossils do not need to exist to fill in gaps in the fossil record for intermediate forms to have existed.Enjoy.

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Thread copied here from the Transitional Fossils Show Evolution in Process thread in the Proposed New Topics forum.

Hi RAZDVery nice presentation refuting this ridiculous claim (amongst others): This claim ignores the rarity of conditions that allow fossilization to occur. It also ignores micropaleontology, the study of microscopic fossils. Finally, it does nothing to explain the fossils we do find, seeming to take an "all-or-nothing" attitude towards this evidence that would have needed to survive for billions of years.In my opinion, the absence of fossils is one of the weakest of creationists' arguments, easily refuted as demonstrated by your comments above.Thanks for the thread RAZD.Edited by Briterican, : No reason given.

This is all truely sad and surely a waist of time, still I will reply because I have the time. Missing links and or transitional fossils are and can be deemed a non cause and effect for both evolutionary theory and creational theory. I think that both evolutionary and creational theories are just that theories and that when one realizes that both are factually the same thus being theories we can all rest from our own convictions of acceptance.

Creationism is not a theory, at least not in the scientific sense. A scientific theory is a framework that explains why a particualr thing is why it is. With evolution for example, the theory of evolution explains the fact of evolution (the fact that allele frequencies change over time in a population). Creationism has absolutely no explanatory power. But they're not the same thing at all, as I just explained.

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I hunt for the truthI am the one Orgasmatron, the outstretched grasping hand
My image is of agony, my servants rape the land
Obsequious and arrogant, clandestine and vain
Two thousand years of misery, of torture in my name
Hypocrisy made paramount, paranoia the law
My name is called religion, sadistic, sacred whore.
-Lyrics by Lemmy Kilmister of Motorhead

And this is what creationism has come down to.You have to insist that looking at the actual evidence is a waste of time, that it is impossible to prove anything, that all belief is a matter of "our own convictions of acceptance" ...You have to insist this, because the facts prove that you're wrong --- and you know it. That's the remarkable thing. You know perfectly well that the facts destroy creationism, so instead of admitting that creationism is wrong, you take refuge in pretending that we can't learn anything by studying the facts. Why don't you just get the words "I'M KNOW THAT THE FACTS PROVE THAT I'M WRONG" tattooed on your forehead?You know perfectly well that the facts destroy your faith. That's why you have to go about telling people that looking at the facts is "truly sad" and "a waste of time".

The only thing that our convictions should accept is the evidence.The difference apart from the fact that a scientific theory by definition can't "just be a theory" is that one can explain the evidence we find well, whilst the other cannot. The Theory of Evolution expects the type of evidence given in this thread regarding transition.From my experience creation "theory" instead tends to keep the stuff that works only. That is not how a scientific theory works whatsoever.Edited by Chippo, : No reason given.

Hi sailorstide, welcome to the fray. Missing links - being missing - don't prove anything other than the evidence is missing.Transitional fossils - fossils intermediate in form between ancestral and descendant forms - can show the hereditary lineage by the progression of change in features over time.This can show the hereditary pattern/s of life from the first forms, whether those are creationist or evolutionary, and thus help us sort between one concept and the other to determine which is the more likely explanation. A scientific theory is based on evidence first, then deduced explanation, then testing and then revision as required to explain all the evidence (the scientific process). Thus there is more to a scientific theory than "just a theory" because there is the evidence supporting it, and the testing that validates it and tests it against reality.Evolution fits this definition of theory as a scientific theory. The evidence is the process of evolution we see in the world around us (where all known breeding populations show change in the frequency of hereditary traits from generation to generation), and in the process of speciation (where a parent population divides into two non-interbreeding daughter populations). These are both observed facts. The theory then, is that these two processes can explain the diversity of life as we know it, from the life around us, from history, from archaeology, from the fossil record and from the genetic record. The testing is every new piece of information about past life, whether genetic or fossil, which can either fit the theory or not.Creationism, as far as I can tell, is not founded on evidence, nor does it appear to do any testing of the creationist concept. Rather it seems to be predicated on the a priori assumption that creation is true. This makes it more of an hypothesis, a conjecture, an assumption, rather than a scientific theory based on evidence first, then deduced explanation, then testing and then revision as required to explain all the evidence (the scientific process).But this thread is not about the issue of what is or is not a scientific theory, so if you want to discuss this further, please start a new topic if you want to pursue this, as I'm sure this is a sufficient topic for a new thread.Go to Proposed New Topics to post new topics. I'm sure you will have plenty of takers. I am not aware of one fact that supports creationism, while I am aware of hundreds that support evolution.Perhaps you can supply us with supporting evidence for creationism? Please start a new topic if you want to pursue this, as I'm sure this is a sufficient topic for a new thread.Go to Proposed New Topics to post new topics. I'm sure you will have plenty of takers. Unfortunately for you, science is not done by popular vote, it is done by actually confronting the evidence and seeing if the theory passes or fails the tests. Thus when the original post states:

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We often see complaints or comments about the absence of fossil evidence for transitions in evolution.

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Often this is due to a misunderstanding of what "transitional" means in evolutionary biology:

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Thus all fossils that show intermediate characteristics between ancestral forms and descendant forms are by definition transitional. Thus whenever we see a clear lineage of fossils from an ancestral form (plesiomorphic) to derived descendant form (apomorphic), and thus they are transitional fossils.

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Transitional fossils will be intermediate in form between ancestral forms and descendant forms, and they will share some, but not all, traits with both ancestors and descendants, and some traits shared by ancestors, the transitional fossil and descendants may themselves be shown in intermediate stages of development, between the ancestral and descendant forms of the traits.

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This thread is intended to discuss and answer this issue.

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The intent is to discuss the evidence that shows intermediate forms in the fossil record. This is done in Message 3, where clear examples of transitional fossils are presented.The logical conclusions are (a) that transitional fossils exist, (b) they show the same kind of change in hereditary traits in breeding populations from generation to generation as we see in life around us today, and (c) they show the same kind of division of parent populations into non-interbreeding daughter populations as we see in life around us today.They are intermediate.They validate evolution and speciation as being sufficient to explain the diversity seen in the course of their fossil record.Enjoy.

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Hi sailorstride Gravity is a theory, but I doubt you'd be willing to test its validity by stepping off a sheer cliff top. You accept it because evidence demonstrates it to be accurate. Evidence can also be used to demonstrate evolutionary theory. No such evidence exists for "creational theories", and I challenge you to present some if you disagree.(Now, after having posted, I'll read the other replies. Next time I'll try to do that first.)Edited by Briterican, : No reason given.Edited by Briterican, : No reason to be nasty.

It is also worth mentioning that one can determine the transitional nature of a fossil without assuming evolution. As RAZD explains so well a transitional fossil is a fossil with a mixture of characteristics. Even if evolution is false these are still transitional fossils.So why do transitional fossils matter in this debate? Because these fossils are a TEST of the theory. How? The theory of evolution predicts which transitionals you should see AND which transitional fossils one should NOT see if the theory is true. This is what is important, how the fossils TEST the theory. The theory predicts that fossils, like modern life, should fall into a nested hierarchy. For example, one should not find a transitional fossil with a mixture of derived mammalian and avian features. Specifically, one should not see a fossil with feathers and three middle ear bones. There are thousands of these types of predictions.Gaps are a very distant, secondary concern. The main point is that each fossil is a new data point that tests the theory of evolution. Nowhere in the theory does it predict that a fossil from every generation of every species that has ever lived will have been found by the year 2010. However, the theory does predict what mixtures of features these fossils will have when they are found.

Hi Taq, love your icon\avatar. A most excellent point, and this also contrasts with the creolution concept of transformation of individual organisms so that there are half formed new features sprouting out of fossils, a cat evolving into a dog, or where new species are formed suddenly by single individuals in one single generation. Creolution claims these are part of "macroevolution", but evolution actually predicts that these type of "transformations" would NOT occur, thus evidence of them would actually be evidence against evolution. Such things are not found in the fossil record or in life around us today.Evolution predicts nested hierarchies via common descent from ancestral populations.In contrast, design (as opposed to creationism ...) would imply that good design features would be replicated, not in a nested hierarchy, but in a manner where new features would be spread across hereditary lineages. We see this repeated again and again in human artifacts and in modern design: the rear windshield wiper appeared on a (iirc) volvo stationwagon, the next year it was seen on many other makes and models, and now is almost ubiquitous on SUVs. We do not see this cross hierarchy design copy pattern in life.Design predicts non-nested hierarchies of features copied across ancestral lineages. We now, in the last 50 years, have a second method to verify the nested hierarchy through genetics. Genetics was\is probably the biggest test of evolution, for there is absolutely no reason for a nested hierarchy to appear in the genomes of organisms without common ancestry being true.We see that similar forms occur with convergent evolution, say of sugar gliders and flying squirrels: So if evolution were not true, that these organisms did not evolve from highly diverse lineages, placental and marsupial diverging long ago, then there should logically be similar DNA for the formation of similar features. Instead genetic analysis says one is placental and the other is marsupial by the nested hierarchies visible in the genetic record. The genetic record confirms the pattern of evolution found in the fossil record.If evolution were not true then there should be homologous DNA for analogous features, and this is not seen in life today. It should be noted that gaps do not disprove evolution unless it can be shown that the development of the (theoretical) descendant could not evolve from the last known (proposed) ancestor. These linkages are usually shown as dotted lines of the proposed hierarchy, based on the best morphological evidence available.We are now seeing those gaps being crossed with genetic analysis, where the homologous structure of DNA forms another system of nested hierarchies. Evolution not only predicts that nested hierarchies occur, but that the same nested hierarchies are found in genetics as are found in the fossil record.Like the double helix of DNA, the double pattern of nested hierarchies is seen in life today, entwined one with the other.Enjoy.Edited by RAZD, : copied

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Actually, these gaps would not disprove evolution unless it could be shown that at the end of such a gap there was special creation of the next form.A gap is simply an unknown, with the dotted lines representing a "best guess" of what went where. And based on our information to date, they may not be correct. Another critter may be found which actually was the ancestor of the guys at the end of the dotted line. That would not disprove evolution in the least, it would just add a missing piece of information and ultimately make the details supporting the theory of evolution stronger and more complete.No, to disprove evolution you need something that absolutely can't be explained by the current theory--some undisputed fact that just doesn't fit, and can't be made to fit.For example, special creation of the various "kinds" about 6,000 years ago would do it, if there was any evidence supporting that belief. At present there is no such evidence.

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Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.