Land Mammal to Whale transition: fossils

I think this topic can be an interesting demonstration of degrees of tentativeness in science. Perhaps we would be best to try to nail down some facts before we get into discussions about what is correct or not.Let me give my overview of the situation:1) Certain characteristics of whales leads one to the conclusion that they are mammals.
2) All the information available suggests that mammels arose, originally, as land animals only.
3) From this it was hypothosized that whales evolved from some unknown land animal.
4) With more details available a particular branch of mammals was suggested as the closest living relatives to whales. (I don't remember which).
5) At a later time genetic sequencing picked a different family for the ancestor.
6) At a still later date additional fossils demonstrated that the correct connection was the one following the genetic sequencing. This resolved the apparent conflict when there was too little fossil information.
7) There is now a series of about 6 or so fossils whose characteristics fit between the early land forms and modern whales. These are what had been predicted many decades before.
8) The available fossils are NOT a step by step series of every single change in the path from land animal to whale.
9) When arriving at any conclusion different individuals will require different amounts of infomation to feel comfortable with the conclusion. An indiviudal may asign greater or lesser confidence to a given conclusion as the available information changes. Thus it should be clear that one individual may give a 10% confidence level that the connection between land animals and whales is a good conclusion and someone else may give an 80% level.At any point in the development of a consensus conclusion it may have varying levels of consensus confidence. The very best level may only be 10% or so but it may still be the best available hypothosis.We can each suggest our reasons for having our own confidence in the hypothosis that whales evolved from land animals. The discussion will be friendlier and more productive is we stick to the reasons and not make wild assertions.

It is, of course, silly to ask for each step in the process. I don't think we will have a productive discussion on that basis.However, I think it is interesting to ask about how many major steps might be possible to ennumerate in the whole process. This is somewhere between 10's and 100's in my opinion.It is then interesting to ask how many and, perhaps, which ones we might want to find to give us different levels of confidence that we understand the evolutionary history of whales "well enough".How much evidence would be necessary to convince each individual will vary as I noted in an earlier post.Will the number of fossils be less if there was a previous prediction of the connection from land to whale?Will the number of fossils be different if the earlier forms support the same conclusion as the genetic sequencing?I think, before we discuss the exact numbers we might want to discuss our thoughts on the above questions.(I think you can guess what my thoughts are)

It seems odd that someone would make such a toughtless statement unless by some unlikely circumstances they had never seen an otter. Since this is not anyone's suggestion of how the transition has occured this too is utter nonsense. This is only demonstrates someone mouthing off from total ignorance.The rest is only slightly less nonsensical.Rather than going for quantity of references, Randman, why don't you actually review what you link to and see about keeping the quality a bit higher?

Could you show your calculations? How many individual whales have lived in the past 50,000 years? How many whale fossils have been found from species extant in that 50,000 years?(we can start with a rough assumption perhaps? -- there were ,until we began to slaughter them, perhaps 20 million whales of all types alive at any one time )Could you define "major forms"? Your numbers are meaningless without that. Perhaps it is time for a taphonmy thread?This message has been edited by NosyNed, 08-05-2005 01:55 PM

One problem that we are all having is discussing this business of speciation from two different points of view.Please review this old post of mine to get a view that is more likely to apply to the whale pathway than one of individual speciation "events" that can be marked in time. Message 161

I'm not speaking to you in admin mode if you have specific things that you think need moderating then point them out.You said this previously: and I am asking you for the details.You said "according to standard TOE models" -- what are those and how did you use them in your estimating?You said "we have fossils of existing whales" -- I'm not aware of any other than bones collected for museums. Could you give some examples and the number of these you used in your estimates.How did you use the curve you referred to earlier?Then there are the numbers questions I asked you before which would be necessary to make such extimates.What taphonomic research did you dig up on the web and how did you apply it?I am in a position of finding your numbers rather incredible but I'm not able to judge that until you show the work you did to arrive at them. Perhaps you have information which makes them sensible.

This is exactly where I think the problem in the current discussion is. In many (perhaps a large majority of the cases) this does NOT occur. There is no point where there is any 'form' which could not (theoretically breed with any of it's earlier ancestors or later descendents over 100's or 1,000's of generations. (For whales this would be a time span of 1,000's to perhaps 100,000 years)When this is the case it becomes very hard to point to an "event". When sufficient generations have past and sufficient change accumulated maybe there is no longer any possibility of interbreeding but there is no line of demarcation anywhere in the continuum.

I have in the immediately previous post attempted to explain about the problem with the term "event".It is a misunderstanding on both sides in the use of terms that hasn't been cleared up yet. It seems to me that it would be a good idea to start a new thread on just this topic. Discussing, perhaps, both the idea of "events" and the chances of fossilization.You have ignored the point in the spectrum analogy of Yaro's. That is, in my mind, a very good analogy to the issue for much (but not all evolutionary change). There is not "color change" event anywhere in the spectrum yet the color is not the same from one side to the other. There maybe in a lineage no speciation event but still the populations are eventually different species.So both sides are right to a degree: there are no events to point to but there are still forms that we could see are different species. The gaps in the fossil record seem to be large enough that all the samples we have are far enough apart to be different species to the best of our ability to tell.However, I think that harping on that issue isn't getting us anywhere but if we clear it up then we can get on with the real points of the discussion.This message has been edited by NosyNed, 08-06-2005 03:48 AM

You arrived at very specific numbers. I, and others, have asked for the calculations you used to estimate them. These have not been forth coming.

Fossilization is, of course, pertinent to this topic. However, it has gone off into generalized taphonomy issues. To allow this topic room to discuss things specific to whales (e.g., what is a cetatcean) I think the fossilization discussion can be spun off.Taphonomy is, on it's own, an important topic to separate for future reference too and I don't think it should be hidden under the whales.

Since we have been at this awhile I'd like to attempt to summarize your arugument to date. If I miss anything please fill it in for us.You seem to have two points:1) There are very few fossils that are claimed to be somewhere related to the hypothosized whale ancestry. You claim this is a greater problem than might otherwise be because a large fraction of all fossils have been found.2) The earlier examples you claim are not whale ancestors or related to them because they aren't whales.Have I missed anything?Now where are we?You have shown very little to support number one. I'd like to see that supplied in the fossilization process. You are the one to has suppled a numberic value. You have yet to support it with numbers.You supplied the discussed curve but have shown no numbers to back it up.2) Neither of us is in a position to judge the quality of analysis done on the ear bones or any other anatomical features. We will have to discuss what is said in great detail by those who have brough expertise to bear. Where are your references to this?As noted by many others; it is expected that there will be only slight changes when a particular branch is starting to "go it's own way". You have not discussed why you think it should be otherwise.As noted by my evil twin -- time to support your arguments.PS my evil twin likes picking on anyone he can. If you think there are unsupported arguments please point them out.

The curve is a presentation of data. What is being asked for is the data that is being presented in this form. Sometimes it is possible to read the underlying data off a curve. For that to be the case there has to be specific values given for the axes. There don't seem to be any.Until you supply the data the curve is useless for coming to any conclusions. With data it might very well be interesting. Because you have put forward the current claim. The curve is not weak - it is without any content at all. Supply the data and it may be analysed.If you would like a rough envelope-back analysis I think I can have a go at one. I'll post that in the fossilization process thread.This message has been edited by NosyNed, 08-07-2005 09:21 PM

see Message 15If your 1,000 species is correct and the numbers given above of 1/10 of 1% is correct then we should find 1 of them. We seem to have 5 or 10?This suggests both that we have done pretty well with this lineage (but it is big and somewhat recent) and that we would expect there to be many more. I agree still that it is a good question. As you point out we have not done a great job of supplying estimates. However, you did supply numbers. We are asking for back up for that. That is the difficult thing about supplying numbers; you have to support them.Why are you not doing that? I've now given a light shot at numbers and given the source for my inputs. Please respond with yours now. We have spent a long time trying to get you to tell us what one of these things we are counting would be. You have, in this post (maybe previously given a bit of what you think). From that definition it makes sense that there would be 1,000 of 'transitionals' since you want rather small changes to count. I don't have a huge problem with the number.You then asked where they are and gave you estimate of the number their should be. However, you did this out of total ignornance of the taphonomic questions.To say that the studies don't exist because I or other amateurs can't find them is a bit premature. I've given you an estimate that says that if there are 1,000's of interesting steps we should find 1 out of each of those 1,000. We are in the right ballpark if those numbers are true.You have suggested that we should find 100's of times more species. You have given no reason why fossilization success should be that high.The total number of species found is very small compared to what would have existed if ecosystems were anything like as diverse as today. This is one strong hint that we are NOT finding 90% of them.