Land Mammal to Whale transition: fossils Part II

This is intended to continue the thread from:
Message 301The basic concept is to discuss two major issues:
1) Is there adequate (not a well defined term) evidence for whale evolution?
2) How many samples along the whale evolutionary path should we expect to find?

Thread moved here from the Proposed New Topics forum.

I'd suggest focussing on this point alone and come to some resolution on it, since it is narrowly defined and could be dealth with on a single thread.If we get into point 1, basically we are going to be dealing with a rehashing of the entire ToE, including genetics, mutation rates, maybe abiogenesis, embrylogy, biasness in evo-evidence (knowledge filter), catastrophic sedimentation, etc, etc,...But we could realistically assess how many transitional forms would be needed between land mammals and whales, how many fossils should be found of these forms, and whether we see those fossils or not.

I don't see how this can be quantified.This message has been edited by robinrohan, 08-08-2005 11:35 AM

Let's see.As far as (1) goes, yes indeed. The hierarchical classification of all species (sorry to go on and on about it, but it is my favorite piece of evidence), biogeographic evidence, molecular biology, genetics, and vestigial organs and atavisms altogether provide pretty conclusive proof that common descent ocurred, and so whales must have evolved from an earlier non-whale ancestor. Note that fossil evidence is really not necessary, and the fact that we have good fossils of whale ancestors is rather embarrassingly gratuitous.

Okay, here is how I propose this problem gets solved. Let's take a modern species, but old enough to find fossils of. Find the number of fossils and how old it is. Do the same thing for three or four other species getting older and older. Then some math whiz can plot this and draw a line of best fit. Then we follow that line back (the appropriate number of years) and then we can make a very shaky guess on the number of fossils that there should be for a givin species.This is a very far from perfect method, but it should give us an idea about the number of fossils we should have, be it tens, or thousands. Just an idea, math people want to elaborate?This message has been edited by Brad, 08-08-2005 12:40 PM

The problem with this is that you have to take into account the rate of evolutionary changes. Take for instance Crocodilians. They have remained pretty much unchanged for several millions of years. (ABE: Several dozen million years!)Also, not all animals fossilize as well because of their environment.how would you account for these factors?This message has been edited by Yaro, 08-08-2005 12:48 PM

There are too many variables.

Yeah, there are lots of problems in this. But I think it could demonstrate that there should only be a handful of fossils, as opposed to the thousands that randman is insisting. But yeah, there are lots of problems. I don't know of a good way to account for the unkowns.

In Part I of this discussion I told randman I would look for better fossilization rate/expectation data: unsurprisingly, I found so much that this Part II thread will probably evolve and die away before I can assimilate it all.But in the meantime, I wanted to share several useful data links. All of these relate to what we might expect to find and what we have found. Each of them has the potential to inform our discussion here. I plan to explore this material in detail, but it will not occur in quick forum time.The first two relate to studies of recent remains in an attempt to better understand fossilization: one primarily on land, one on the beach:I.

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Scientists have begun to study the fossilization process to understand how likely various species were to be preserved.

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That information could revise some estimates of the relative abundance and dominance of various animal species in the fossil record.

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In one long-term investigation, researchers have been studying the bones littering the landscape in Kenya's Amboseli National Park, a 392-square-kilometer reserve just northwest of Mount Kilimanjaro. During the dry season, wildlife flocks to the park's spring-fed marshes. Amboseli also contains woodlands, grasslands, and a low area that becomes a lake during rainy spells, says Anna K. Behrensmeyer of the Smithsonian Institution in Washington, D.C. She and her colleagues have systematically scoured certain paths across the plain and through the woodlands of the park since the 1970s, recording the bones they find. Most they leave in place and revisit during later surveys, but some they take back to the lab for identification and analysis.

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The article is from Science News Online, but there are linked journal citations.http://www.sciencenews.org/articles/20030719/bob10.aspII.
The second specifically addresses marine mammals in the Northern Gulf of Mexico. The link is to a complete journal article (pdf):

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Bones on the Beach: Marine Mammal Taphonomy of the Colorado Delta, Mexico

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How well does a death assemblage of marine mammal bones reflect the diversity, species composition, and proportion of bone types in the living fauna?

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http://www.geo.arizona.edu/ceam/BonesOnTheBeach.pdfIII.
Last but far from least (in fact, it is awesome, and my new favorite toy...). Check out the animated growth of the database (lower right on the linked main page):

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The Paleobiology Database is a public resource for the scientific community. It has been organized and operated by a multi-disciplinary, multi-institutional, international group of paleobiological researchers. Its purpose is to provide global, collection-based occurrence and taxonomic data for marine and terrestrial animals and plants of any geological age, as well as web-based software for statistical analysis of the data. The project's wider, long-term goal is to encourage collaborative efforts to answer large-scale paleobiological questions by developing a useful database infrastructure and bringing together large data sets.

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This hour's Database totals
14080 published references
52353 fossil collections
514558 taxonomic occurrences
entered by 157 researchers from
77 institutions in 14 countries

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John Alroy, a palaeontologist at the University of California, Santa Barbara (UCSB)...is one of the founders of the Paleobiology Database, a project set up in 2000 with financial support from the US National Science Foundation. This freely accessible database [is] hosted by UCSB's National Center for Ecological Analysis and Synthesis.

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http://paleodb.org/cgi-bin/bridge.plAgain, I apologize for not connecting more dots before posting these, but they may help ground the discussion.

I think however it should be done for whale families or other closely related semi-aquatic families. I initially felt fossils of species would be the way to go, but really to be fair, some whales can breed across genera, and if evos can show the numbers of whale transitionals at the family level needed, that would be good enough.Plus, we are likely to find more data documenting whale family lineages than mere species. So it may be too difficult to do this at the species level, not because the data is not there, but it may not be organized at the species level per fossils.Another approach is to quantify the range of differences and view particular traits as they appear in the fossil record. For whales, we could identify whale similarities and the differences in whale traits that create the range of current living cetaceans. Then see how many fossils per this range appear.Presumably, if we are to include then a much wider range of traits, which would be exhibited in the transitionals, then we should see a wider range and number of fossils.This message has been edited by randman, 08-08-2005 10:05 PM

As I mentioned in the original thread I believe this part of the question is a non-starter. Perhaps a professional or a more knowledgable (than me) amateur can explain why the reasoning below is wrong.To answer the question "How many samples along the whale evolutionary path should we expect to find?" we need to be able to guestimate at least two numbers:

• How many identifiable species would we expect in whale evolutionary history?
• How many of these species can we expect to find in the fossil record?

Number 1: How many identifiable species would we expect in whale evolutionary history?
As far as I am aware none of the science disciplines allow us to predict this number. Essentially all the ToE can do in this situation is say that between an ancestor species and a descendant species there will be intermediate species showing features somewhere between the two in a kind of sliding scale.Number 2: How many of these species can we expect to find in the fossil record?
Again I would say this number cannot be predicted. There are just too many factors involved, not the least of which is dumb luck. Others include (off the top of my head) environment, subsequent erosion or other means of destruction such as subduction, population size - I'm sure there's lots more. Ultimately we have to calculate how many of the intermediate species would have at least one member fossilise and then how many of these fossils will survive to the present and be found by us. We can't answer either of these.I can believe that you might be able to produce a formula that provides the answer to the question "How many samples along the whale evolutionary path should we expect to find?". It would unfortunately be like the Drake Equation for working out how many civilisations exist in the Galaxy. We don't know the values to use for so many of the terms that by using different values you can get pretty much any answer from 0 to billions.

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Oops! Wrong Planet

MangyTiger, I agree.However, the questions I want to address are somewhat different.I believe that creationists choose cetacean evolution to scrutinize because of the perceived counterintuitive nature of evolution from four-legged land animal to fully aquatic mammal. Thus, the supposed gaps between cetacean fossils loom relatively larger in their eyes. Simply put, it is to creationists an especially large incredulity...leviathan, really However, given the ways in which the marine environment is hostile to the preservation of mammal remains, I would assert that a comparison of ancestral whale fossil finds to large land mammal ancestral finds shows that the evolutionary lineage of cetaceans is well represented. My first two links (esp. since the second directly references the first) go some distance toward defining the likely difference in preservation. Also, both studies underscore the genuine rarity of fossilization, and the absurdity of insisting that every genera and species should be present in the fossil record.I also want to demonstrate that, far from dodging questions about the fossil record, scientists have been working for decades to define taphonomic processes and expectations: far from needing to run and hide from the question, scientists have addressed it with rigorous research for many decades.Of course, the question of "How many samples along the whale evolutionary path should we expect to find?" only makes sense with the assumption of evolution (file under delicious irony), and only when gauged relative to the number of "samples" we have found in other evolutionary paths--the absolute numbers of either may be meaningless, but the relative comparison may not.I am looking not at how many whale samples we should expect to find, which is unanswerable, but rather, have we found a reasonable number?So...off-topic? A fool's errand? It promises to be a lot of work, and if I am only going to entertain randman, I'd rather drink beer.This message has been edited by Omnivorous, 08-08-2005 11:47 PM

Since it seems we are throwing too many things out at once let's see if we can get on the same page for just one concept.Speciation EventAn "event" implies to me something which occurs in a localized place and time.
Let's start with a population of individuals that are under selective pressure for a number of generations let's say 1,000,000 generations. every 10,000 generations we are able to examine and test the population and we find that each time the population every 10,000 generations can not interbreed with either population -10,000 or +10,000 generations (that is the population of generation 30,000 can't interbreed with generation 20 or 40 thousand).I think you would then say we have 100 speciations, correct?But if we test the 10,000th population with the 5,000th and the 15,000ths they can still interbreed. And the 5,000th with the first and the 15,000th with the 20,000th can still interbreed. So the speciation event did not happen between the 5,000th and the 10,000th for one thing. But the 5,000th can interbreed with the first so it there was no speciation between those. So where was this localized "event"?The real case may, of course, be more complex than this if the population split into multiple separated populations but even it the "tests" were conducted with populations that are before and after a split the results will still be the same. I won't go in to the extra complexity here since it is not important.The spectrum of light is analogous to this. That is it is an aid to understanding the concept. Which you have yet to give a reason to think that you have gotten yet. The frequency spread of light is analogous to the time span of the populations. The color of the light is analogous to the species of the populations. Yellow is one species , red another an so on. There is in the spectrum no "event" where red turns to yellow. That is all the analogy is trying to point out nothing fancier.Now why would you have or not have "missing links"? What is the difference in your picture from the picture I have painted above and why does it produce "missing links" (please define what they are) and the above scenario not produce these things.Since this is off topic for the fossilization process I am replying here. Please refer to: Message 56Please explain "new" and "prior" group. About the only way I can see this being different from the above simplified scenario is if the new group and prior are just one generation apart. This is in no way what is suggested for most evolution and particularly the evolution of whales. We have fossil samples spread over several 10's of millions of years. They would 10,000's to 100,000's of generations apart if were in a direct ancestral line to each other. At each point they have some differences to the points earlier and later. The differences are just what would be expected if there were a continuous series of changes between them. The size of the "leaps" are not particularly large over the time spans involved.So one possible explanation for the pattern is that these represent samples in the continuous evolution of whale ancestral forms. The data in entirely consistent with that idea.What other explanation do you have? This is simply mumbo-jumbo and if you use it as an excuse for anything again you will be suspended.

The spectrum analogy misleads rather than illustrates, and here is why:1. The spectrum is generated by a single quanta of light, correct, and the frequencies do not evolve into another, but the light photon instantly includes all frequencies at once, and is thus the antithesis of evolution.2. The spectrum analogy, if accurate even in the misconception of one form bleeding into another form so to speak, suggests one single life form that gradually in toto evolves into new life forms. If this was the process of evolution, there would be no branches, but just one long single line of evolution. This is not, in fact, what we see in current species or in the fossil record. If what you are claiming is ToE, then it never happened.3. What you are ignoring is that in the context of this discussion and in general, evolution for sexually reproducing species occurs within discrete groups.4. You claim species evolve in a manner where it is difficult to draw a line where one era of the mammalian species could not mate with it's ancestors, and thus it is difficult to determine when a speciation event takes place.Can you back that up and show studies of mammals, preferably whales, that show that?