Land Mammal to Whale transition: fossils Part II

Could you describe why you think it is based on an evolutionary model. All I see it based on is the fact that we have a change over in the species existing. As I said I don't care how they changed but we have the evidence that they did.Why would recurring creation reduce the number of species? The average lifetime between extinctions and new creations is as we see anyway.

A tree shrunk down to 3 feet high (.9xx m) would not look like a bush. The reason for the bush analogy is a bush has no main stem. A tree looks like it is "going somewhere". The branchs are there of course, but they are generally clearly preripheral to the main stem (conifer I guess) and it appears to be heading to a pinnicle.A bush (once above the very base) is a tangle of branchs no one of which seems to be dominant.

the 10 or so Myrs is about right as randman notes. The archecetacean were fully aquatic by that time.

Basilosaurus was, it seems, around for about 5 million years. Have you attempted to figure out how many individuals of that species may have lived in that time.This is a place where you might use numbers from extant whale species. Why don't you demonstrate an ability to make such an estimate (we aren't worried about precise accuracy just reasonableness of approach).

There are estimates that the eastern pacific gray is back up to about historic figures (though some historic numbers may be low by a factor of 10).That beastie is about the size of a basilosaurus. It doesn't range over the whole ocean and this is only the eastern population so you are right we might get an underestimate if we used the 20,000 of them as an example.But, let's see how randman can do with these inputs.(btw I think a reasonable whale generation is 50 years)

How about we use half of the population of one subspecies of extant whale?There are about 20,000 eastern grays now. That is estimated to be about the historic population.Let's use 10,000 as the world wide population average of all the Basilosauri species as compared to one group of a the grays (there was a western population of grays too but there are few left).Whale generations are a few decades long. I think we would be pretty close if we took 50 years. Ok with you?The basiosauri were around for about 5 million years as you have noted elsewhere I think. That is 100,000 generations.If the population averaged 10,000 individuals there were about 1 billion of them alive at one time or another. If we have found 1 MILLION fossils of them (which is about 3 orders of magnitude too high isn't it?) then the found fossils represent .1 % of them.Care to comment? I'm sorry to do complex things like multiple and divide but counting colored balls one at a time was too time consuming.ABE
As you can see the final answer give low fossil "hit" rates within a wide range of estimates for the inputs.PS If I use a modern whale suborder I'd be forced to use an average population that would be at LEAST 10,000 and 100,000 would be more like it so let's use the smaller grouping to not over estimate the numbers of individuals.This message has been edited by NosyNed, 08-16-2005 02:06 AM

You are right. If Basilosaurus is representative (or less likely to give us fossils than the transitionals that came before) we should get from 1 to 10 specimens of each.However, Basilosaurus is useful to give us an estimate on one extreme. It shows that even in this case ( a larger, long lived population) your initial idea of how many fossils we should find are out by a factor of at least 1,000.Now we are after the number of fossils for the species involved in a narrow geographic region and for much less than 5 million years. With such small numbers of fossils expected (somewhere between 10 and less than 1) we run into statistical fluctuations which can easily remove any for a particular species. So we are in a range where missing a species is no longer so impossible at all. What do we expect now?It is time to look in more detail at the first 10 million years of archeoceti evolution then.I don't think that a population would be viable at less than 1,000 individuals and since we are looking at small populations that allow the rapid transition from land to aquatic in the time from about 53 Myr ago to 40 Myr ago then the population could not be as big as the 10,000 of Basiosaurus.I think, to be fair, we would have to drop the average generation length from that of the larger, later whales -- say 13 years to make the calculations easier. (I'm picking numbers here to help your case)We end up with a million generations. If we use 1,000 as the population we have 1 billion individuals and should expect to have a total of about 1,000 fossils. If we go up to the larger population we expect about 10,000 fossils.I don't know how many we have but I'm pretty sure we don't have 1,000 across this 13 Myr time frame. We are missing 100's of fossils.You are wrong and right: found fossils are rare (very rare) but we still don't have enough in the 13 Myr transition time.Does that mean they aren't there? The numbers aren't conclusive. Now if we are out by a factor of only 10 in any of the inputs we find ourselves with a number that does correspond to the number of fossils found.However, I can't think of a way of refining this to sort out which it is.You have been ranting over something that can't be driven to a very conclusive final answer. Fossils are very rare (based on all the numbers we have been able to cobble together. But there are hints that we should have more transtionals from the early eocene.I am more curious now about how many we do have. We have a handful of species from that time frame, no? We have more than one sample of some of them. We might have as many as 100 fossils (I'd be surprised if more). I'd be happier if we had 1,000; you'd be happier if we had 10.Where are we? Undecided.

You are doing something that is careless. Choosing to push the input in the direction of the results you want. Is this for Basilosaurus? That isn't out of line based on modern whales but from what I've read Basilosaurus might be less than wide open ocean going (of course we don't find fossils from the deep oceans so that might be wrong). However, we are finding fossils only where the oceans were over present day land. Using a larger population size is worse for your case so I shouldn't mind. It seems to big to me though. The old estimates for some of the open ocean whales (like the right and humpback) IIRC were about 20 or 30 or so 1,000 individuals; recent studies suggest that they may have been 10 times bigger which supports the 100, 000 population number but to be less supportive of my side let's stick with only 10's of 1,000's. I disagree. One to a few 1,000 fossils would be a very large number for this type of beastie. I'd be less surprised if we had just a few 100 world wide. Maybe someone can research this and give a more definitive answer. We are in disagreement by a factor of 100 here.I think the 100,000 generations is pretty fine. I don't think it can be low or high by more than a factor of 2.{qs}That is 10,000,000,000 species that ever lived.[/qs]Whatever the inputs this number is for numbers of individuals that have lived NOT species. That is the number of individual Basilosauri who lived.I think your estimate of the population is high by about 10 and the number of found fossils is high by about a factor of 100. This would make your odds about 100 million to one. If I am right about population and you are right about fossils the odds are 10,000 to one. If I am right about fossils and you are right about population then the odds are 1 billion to one. We need better estimates of those things.I think the idea that there should be 100's of millions of individuals over the time frames is about right. This applies however they are divided up into different species. This somes from the large number of generations primarily. It is hard to pick a reasonable population that doesn't produce a lot of individuals over 10,000,000,000 years.We are talking about the transition period. The populations will be smaller -- 1,000 we can use for now (it is good for my view ) but it is as small as I think we can use.Now we have odds over too wide range to settle this. We also have to be careful in a detailed way that Basilosaurus is representative of the transitional populations. Basilosaurus swam in seas that have since retreated. If, once they left the land for good, the transitionals were in the Indian ocean where it is today then we loose them all. Now we need to know where the seas were during the time from 53 Myr to about 40 Myr ago. (Clearly by 40 they were over places where we should be able to find fossils).Then we have to see if the transitionals were in places as combed for fossils as Basilosaurus. Pretty sure not since Louisiana (for example) is a lot more accessable than the pakistan. Even if all the various numbers are right and we should see 5 fossils (that could be 50 or less than 1) every 2 million years then we are now down to numbers where just plain bad luck can stop us from finding a species.At your 5 number we should have something like 25 or 30 separate fossils from the transition period. That is about how many we have within a factor of two I am guessing. I'll bet we have more than 10 and expect it is more like 20. Now we need to count those too. I'm too tired to dig deeper into it.As I said before. The numbers are not as overwhelmingly convincing as you were suggesting. In fact, they are starting to look more like what you were told in the first place. If we have many millions of individuals then we might start to hope to find a handfull of them fossilized. This is no longer a guarenteed sure thing. It is certainly enough to allow the other morphological and genetic evidence to guide us without worrying that we are missing something important.

Thanks for the note regarding time.The numbers we are discussing here are NOT species they are individuals (that's twice).I'd agree that 1,000 individuals is about the bottom of the range I would be comfortable using while 10,000 is, perhaps, the upper end.I too would like someone who knows more to comment.

It doesn't help to simply make statements about what you think the answer should be or that you think Basilosaurus is an "anomaly".You have to back up to the input assumptions, give specific reasons why you would use different inputs and redo the calculations, correcting if need be.You haven't done that here so this post isn't very helpful.The Basilosaurus may very well not be representative enough but it is one of the inputs we have available to us right now.

I picked the example since he had talked about it a lot and he was suggesting that there were such a large number of fossils of it.We don't have enough hard information to get more than ballpark estimates but what we do have suggests that randman's idea that a large fraction of a population will fossilize was wrong by a factor of from 100 to, perhaps, 10,000's.

They do not work in your favour at all. As I recall the only number you gave for fossilization percentage was 90%.The numbers we have suggest that is 100 times too high. It may be more like 100,000 or a million times too high.Your idea that fossilization is not rare is contrary to what these ballpark estimates give us.Now we find that the ballpark estimates are too rough to figure out whether we should expect total absence of some transitional species or that we should expect to find a handfull of them.Your initial idea of what was going on are NOT supported by this.However, I think we are now, as many have indicated in an area where there is inadequate information to be precise enough to come to a conclusion. We have probably also, finally, run out of things to do with this.

I don't understand : Could you explain? Maybe. We may well have all of the major transitions in the fossils we have. Any way to tell?

Have you read over the last day or so of this thread?

If there are, in fact, some examples of exactly this will you get off this mistaken idea? You have never given a good reason why there should be such large numbers of intermediate species. You have ignored a number of reasons given to you as to why we might not. There are not 10,000's of Basilosaurus fossils. You have been given a number of reasons for this. Will you show how they don't apply in the case you are talking about? You seem to have trouble dealing with more than one simple thing at a time.You almost answer your own question in the next paragraph. How many Basilosaurus fossils do we find in the habitats that current (and not so distant) whales occupy?