Transitional Fossils

[Jose]

Creationists seem to claim that no transitional fossils have been found, thus disproving the theory of evolution. Evolutionists claim to have found very many of them. What's going on?

1. What is a transitional fossil?
2. What would one look like?
3. What are your criteria for coming to these conclusions?

I've put in the last question as an afterthought. It might help us resolve differences in our definitions.

[micatala]

In real life, though, it's not like that. We might have a few fossils from time A, a few from time Z, and maybe one each from times D, H, R, and W. To find "intermediates," we'd look for more fossils--from the time periods from which we don't already have examples.

. . . .

This is the type of situation that exists for most of these morphological transitions. There are some fossils, but not a fossil of everything that lived in that time interval. There are time periods from which we have not yet found fossils of this type of critter.

Just to elaborate a bit by thinking out loud, my understanding is that the reason there may be no fossils at a locatation at a particular time N is that no sedimentary layers were formed in the particular location at that particular time, to do the conditions prevalent there at the time. So, the 'gaps' in the fossil record might be (and probably largely are) due to lengthy time periods where sediments were not laid down, which would mean that organisms dying at that location and time would not be fossilized.

It seems to me, then, that there are some gaps in the fossil record that might never be filled because certain species might have lived only at times and places where fossilization just never occurred. Sort of like if you 'lost your marbles' by dropping them on the street, and then that spot was run over by the street sweeper and your marbles were sucked up and destroyed, never to be seen again. If you had dropped them on the grass instead, you might have found them (if the lawn mower had gone by in the meantime). The potential fossil organisms would all be destroyed if the conditions for fossilization did not occur.

I think this is implicit in what you wrote, but thought it was worth making explicit, and also this way I can be corrected if my 'reading between the lines' is incorrect.

[Jose]

Thank you, micatala. You have, indeed, read between the lines quite nicely.

I'll add another out-loud-thought. I've been collecting in a number of places where the boundary between ocean sediments and terrestrial sediments moves some direction (let's say westward) as you move upward geologically. Imagine, for example, the sea level changing, so the coastline changes--and with it, the narrow zone where the critters live. So, you wouldn't just move a few layers up and start looking for the next set of fossils--you'd have to move a few layers up and a few kilometers to the west. If we're talking about a transition that took ten million years or so, there are lots of opportunities for re-arrangement of the coastline.

There's also been a year or two during which the strata have been eroding, so the "best" location for the fossils we seek may already have eroded to dust.

[rigadoon]

Fossils from the same stratum (ie, the same narrow band within a larger group of strata) are contemporaneous. No ordering is needed. After all, we don't try to make "an evolutionary series" of currently-living humans, trees, cockroaches, and malaria parasites. They're all living at the same time, and can't be each other's ancestors. From within a stratum, just like now, the individuals that you find (fossils for strata, living individuals for the present) inform you about the diversity present at that time. The diverse collection, whatever it may be, is only one snapshot in time.

The Fact of Evolution is revealed by the Fact that different shapshots from different times show us different life forms--different diversity at each timepoint.

...What we have is a bunch of collections of fossils, each from different times. Each collection is a sampling of the diversity from that time. The older collections preceded the younger collections in our time-series. Within each collection, however, there is no "order" because we're talking about things that lived at the same time.

(1) So the kind of evolution you're talking about is change from diversity1 to diversity2. There should be some good ways to measure the differences between these diversities. What measures do you use? This should lead to a way of ordering diversities.

(2) So "evolution" is a technical term indicating differences in diversities at different points in time.

Theoretically, if we were really lucky, it might be conceivable that we could collect zillions of fossils from the bottom-most stratum to the top-most stratum--let's say from A to Z--and thereby obtain a detailed view of the complete diversity of life throughout that time interval. Then, it would merely be a matter of matching the most-similar critters from strata immediately above and below, and we'd have a reasonable series. Then, we'd just look at 'em, and say "aha. This is what the intermediates look like--we know because we have them."

In real life, though, it's not like that. We might have a few fossils from time A, a few from time Z, and maybe one each from times D, H, R, and W.

So in real life, the fossil record doesn't present compelling evidence for common descent (though it might be consistent with it). Evolution in the technical sense above is found.

To find "intermediates," we'd look for more fossils--from the time periods from which we don't already have examples. Of course, we can only look in those rock formations that are exposed on the surface, and have had enough erosion to begin to separate the fossils from the surrounding rock, but not so much erosion as to destroy the fossils. Regrettably, the current erosion patterns that expose rock formations have no interest in providing us with ideal fossil-collection sites. So, in practice, this amounts to a lot of hiking and looking, with occasional lucky breaks.

So, if we find a fossil from time-period L, we know it's between H and R. If it's a tree fossil, we don't bother to consider it as an intermediate between lobefins and amphibians--it doesn't fit any of the predictions. If it's the right kind of critter, though, it might be an intermediate.

From what you said before, A to Z should be different diversities, so "intermediate" should refer to an intermediate diversity. To know what this is, one needs an ordering principle for diversities. Do you have one?

[Jose]

You've confused me, rigs. The fact of evolution comes from comparing the things-that-lived-at-time-1 to the things-that-lived-at-time-2, and finding that they are, in general, different. The "diversity" bit refers to the fact that, at every timepoint, there's more than one species.

For a "series," you look at the same "kind" of critter (or plant). It makes no sense--as I'm sure you know--to refer to "intermediate diversity." You'd need to look at "intermediates" in every lineage.

So in real life, the fossil record doesn't present compelling evidence for common descent (though it might be consistent with it). Evolution in the technical sense above is found.

It provides compelling evidence when you look at the entirety of what's known. Of course, one could imagine other explanations for the data besides inheritance from a common ancestor...at which point the genetic data come in, with a nested hierarchy of DNA sequence differences/similarities. Two completely different types of data produce the same explanatory model--and one of those datasets is possible only by real genetic inheritance (or, as always, god creating things to look like evolution is true, just to trick us).

But, these questions of yours are not really on the topic of this thread. Let's get back to it. what would the intermediate forms look like?

[rigadoon]

But, these questions of yours are not really on the topic of this thread. Let's get back to it. what would the intermediate forms look like?

The word "intermediate" implies an ordering. I've been trying to get you to say what the ordering is and the closest you've come is to say that strata containing fossils are ordered by geologists.

There must be an order of fossil "forms" for the term "intermediate form" to make sense. What is that order? If that order is scientifically understood, then there should be some kind of law or principle behind it. Use that principle to determine the intermediate forms. It's like interpolation of a mathematical series.

[Nyril]

There must be an order of fossil "forms" for the term "intermediate form" to make sense. What is that order? If that order is scientifically understood, then there should be some kind of law or principle behind it. Use that principle to determine the intermediate forms. It's like interpolation of a mathematical series.

Well, following that reasoning the answer is exceedingly simple. All fossils are intermediate. Each and every fossil depicts a particular moment in time during the evolution of a particular species. Every dinosaur fossil is an intermediate as it depicts something before what we have now, every fossil after is an intermediate, and so forth. If you could make a fossil at this very instant of a living creature it would still be intermediate because hopefully that species would be reproducing.

The only exception of my rule is if you happen to have the fossil of the very last creature of its kind. No eggs waiting to hatch, no others to reproduce, the very last fossil. I will concede that in that case you wouldn't have an intermediate.

[Jose]

There must be an order of fossil "forms" for the term "intermediate form" to make sense. What is that order? If that order is scientifically understood, then there should be some kind of law or principle behind it. Use that principle to determine the intermediate forms. It's like interpolation of a mathematical series.

It's really not that hard. Ancient Ancestors-->Ancestors--> Descendents. I've given you the Ancient Ancestors and the Descendents, and asked you what the Ancestors should be like.

You can quibble all you like about the order of the fossils. That's not what I'm asking about. I'm asking for the particular transition I've provided, what should the intermediates be like? You may call this a hypothetical question if you cannot convince yourself that such a transition could occur. You must, however, agree that the way families work, parents have offspring, and those offspring have offspring, etc. Given enough time, every family has to have ancient ancestors, ancestors, and descendents. That is the scientific principle which you seek. It doesn't seem very mysterious to me.

As I have said, the order is determined solely by the ages of the strata in which the fossils are found. Older fossils are candidates for ancestors of younger fossils. It certainly can't be the other way around.

[rigadoon]

Jose, you said back in #99:

Let me rephrase it: Evolutionary theory proposes that current species evolved from earlier species, which evolved from even earlier species. According to this theory, there should be a continuous lineage from one species to the next--i.e. there must be transitional individuals along the way. How would these transitional forms be recognized? What would they look like?

That is, we are asking what should exist if the theory is correct. This is, in a sense, a way of testing the theory. If transitional forms must look like XXXXX, but XXXXX is never, ever found, then it would seem that the theory cannot be correct. Needless to say, this test of the theory depends on the predictions of what the transitional forms should look like.

So the transitional forms should be predicted by the theory. It's not my theory so I'm not the one to answer that. But if the answer is still unclear that imples the theory is still under development.

...You must, however, agree that the way families work, parents have offspring, and those offspring have offspring, etc. Given enough time, every family has to have ancient ancestors, ancestors, and descendents. That is the scientific principle which you seek. It doesn't seem very mysterious to me.

I wouldn't call reproduction a principle. It's something that is observed and since it's a binary variable (an organism does/does not reproduce), it's easy to extrapolate back. Back to what? No beginning, a common beginning, multiple beginnings, whatever -- reproduction doesn't provide an answer.

[Jose]

Let's look back a bit further, rigadoon. In the thread, Is Science True, you said

So there's a possible transitional creature. So there's evidence of one evolutionary transition. How many transitional fossils are observed? How many transitional creatures are claimed to have existed? By the evidence, only a few transitional creatures existed.

You later responded to Grumpy with

The fossils do not show a step by step transition from one specimen type to the next, from marine invertibrates to mammals. So this argument is essentially saying, "Fossils are different, therefore change happens, therefore Grumpy evolution is demonstrated."

Now, it seems to me that to make these statements, you imply to the reader that you know what transitional fossils are and what they look like. You would have to, if you claim that, accoding to "the evidence, only a few transitional creatures existed," or that the "fossils do not who a step by step transition." You spoke then as if you knew what transitional fossils were, and that you believed that few, if any exist. We merely ask you, here, to support that implicit claim.

In order to make those prior statements, you would have needed your own answer to the question you now claim isn't yours to answer:

So the transitional forms should be predicted by the theory. It's not my theory so I'm not the one to answer that. But if the answer is still unclear that imples the theory is still under development.

It seems somewhat puzzling that one can, essentially simultaneously, claim that it is the job of the evolutionists to tell you what transitional forms should be like, and claim that few or no transitional forms exist, even after being told quite clearly what the theory predicts transitional forms should be like. How do you justify this?

You're right. Evolutionary theory makes very clear predictions. Despite this, creationists claim "there are no transitional forms." You have made essentially the same claims. Why? What do you think transitional forms should be like? You are the one who claims that the fossils don't show what you predict. Can you support this claim, or is it baseless?

There must be an order of fossil "forms" for the term "intermediate form" to make sense. What is that order? If that order is scientifically understood, then there should be some kind of law or principle behind it. Use that principle to determine the intermediate forms. It's like interpolation of a mathematical series.

It's really not that hard. Ancient Ancestors-->Ancestors--> Descendents. I've given you the Ancient Ancestors and the Descendents, and asked you what the Ancestors should be like....You must, however, agree that the way families work, parents have offspring, and those offspring have offspring, etc. Given enough time, every family has to have ancient ancestors, ancestors, and descendents. That is the scientific principle which you seek. It doesn't seem very mysterious to me.

I wouldn't call reproduction a principle. It's something that is observed and since it's a binary variable (an organism does/does not reproduce), it's easy to extrapolate back. Back to what? No beginning, a common beginning, multiple beginnings, whatever -- reproduction doesn't provide an answer.

It provides an answer to the question that you asked. Invoking a different question now doesn't change the fact that we answered your prior question. You asked what provides the order in the series. The answer is reproduction. Parents come before offspring in any normal time series, generation after generation. You said that whatever law we're dealing with, it should be possible to interpolate, as in a mathematical series. Well, you can do so here: what's between "grandparents" and "children"? Did everybody get "parents"? Or, do we have evidence that reproduction worked some other way?

Since it's so easy to make this mathematical interpolation, and since your prior statements indicate that you have in mind a model of what transitional forms should be like, it should now be easy for you to answer the simple question laid before you: what do you think the intermediates should be like in the family lineage in which there occurred the transition from lobe-finned fish to amphibians?

[rigadoon]

Let's look back a bit further, rigadoon. In the thread, Is Science True, you said

So there's a possible transitional creature. So there's evidence of one evolutionary transition. How many transitional fossils are observed? How many transitional creatures are claimed to have existed? By the evidence, only a few transitional creatures existed.

You later responded to Grumpy with

The fossils do not show a step by step transition from one specimen type to the next, from marine invertibrates to mammals. So this argument is essentially saying, "Fossils are different, therefore change happens, therefore Grumpy evolution is demonstrated."

Now, it seems to me that to make these statements, you imply to the reader that you know what transitional fossils are and what they look like. You would have to, if you claim that, accoding to "the evidence, only a few transitional creatures existed," or that the "fossils do not who a step by step transition." You spoke then as if you knew what transitional fossils were, and that you believed that few, if any exist. We merely ask you, here, to support that implicit claim.

Grumpy pointed to an Archaeopteryx fossil as "a transitional creature indicating that birds did evolve from therapod dinosaurs". So it was his claim and I didn't dispute it but merely agreed "there's a possible transitional creature". But as you quote I also claimed that the step by step transition required by a theory of evolution (as opposed to a theory of revolution) was not there. What's a "step"? A small change so that the differences between two fossils in the series are minor (this could be formalized in various ways).

So the transitional forms should be predicted by the theory. It's not my theory so I'm not the one to answer that. But if the answer is still unclear that imples the theory is still under development.

It seems somewhat puzzling that one can, essentially simultaneously, claim that it is the job of the evolutionists to tell you what transitional forms should be like, and claim that few or no transitional forms exist, even after being told quite clearly what the theory predicts transitional forms should be like. How do you justify this?

Ok, I'll go farther than that. I'll challenge the assertion that there is any fossil evidence for evolution. Now it's up to the proponent of the theory to propose exactly what that evidence is. So far I haven't seen the case for a way to interpret fossils as a series of parent-child fossils.

You're right. Evolutionary theory makes very clear predictions. Despite this, creationists claim "there are no transitional forms." You have made essentially the same claims. Why? What do you think transitional forms should be like? You are the one who claims that the fossils don't show what you predict. Can you support this claim, or is it baseless?

The only prediction I'm making is that the word "evolution" requires a step-by-step series of changes, which means minor differences in a series of fossils.

There must be an order of fossil "forms" for the term "intermediate form" to make sense. What is that order? If that order is scientifically understood, then there should be some kind of law or principle behind it. Use that principle to determine the intermediate forms. It's like interpolation of a mathematical series.

It's really not that hard. Ancient Ancestors-->Ancestors--> Descendents. I've given you the Ancient Ancestors and the Descendents, and asked you what the Ancestors should be like....You must, however, agree that the way families work, parents have offspring, and those offspring have offspring, etc. Given enough time, every family has to have ancient ancestors, ancestors, and descendents. That is the scientific principle which you seek. It doesn't seem very mysterious to me.

I wouldn't call reproduction a principle. It's something that is observed and since it's a binary variable (an organism does/does not reproduce), it's easy to extrapolate back. Back to what? No beginning, a common beginning, multiple beginnings, whatever -- reproduction doesn't provide an answer.

It provides an answer to the question that you asked. Invoking a different question now doesn't change the fact that we answered your prior question. You asked what provides the order in the series. The answer is reproduction. Parents come before offspring in any normal time series, generation after generation. You said that whatever law we're dealing with, it should be possible to interpolate, as in a mathematical series. Well, you can do so here: what's between "grandparents" and "children"? Did everybody get "parents"? Or, do we have evidence that reproduction worked some other way?

Fossils don't reproduce so we can't observe who is who's parent etc. Someone needs to make a case that the fossil record can be interpreted in terms of "fossil X is a parent of fossil Y" etc.

Since it's so easy to make this mathematical interpolation, and since your prior statements indicate that you have in mind a model of what transitional forms should be like, it should now be easy for you to answer the simple question laid before you: what do you think the intermediates should be like in the family lineage in which there occurred the transition from lobe-finned fish to amphibians?

The only model I have in mind is the step-by-step model that justifies the name "evolution".