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Thread: Study Re-evaluates Evolution of Mammals

  1. #1
    popopot's Avatar To Me, To You BT Rep: +5
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    From: http://www.nytimes.com/2007/03/28/sc...gewanted=print

    The mass extinction that wiped out dinosaurs and other life 65 million years ago apparently did not, contrary to conventional wisdom, immediately clear the way for the rise of today’s mammals.

    In fact, the ancestral branches of most mammals, including primates, rodents and hoofed animals, emerged long before the global extinction and survived it more or less intact. But it was not until at least 10 million to 15 million years afterward that the lineages of living mammals began to flourish in number and diversity.

    Some mammals did benefit from the extinction, but these were not closely related to extant lineages and most of them soon died off.

    These are the surprising conclusions of a comprehensive study of molecular and fossil data on 4,510 of the 4,554 mammal species known to exist today. The researchers are to report the findings in Thursday’s issue of the journal Nature, and they said this is the first virtually complete species-level study of existing mammals.

    Writing in the journal, the leaders of the project said the “fuses” leading to the explosive expansion of mammals “are not only very much longer than suspected previously, but also challenge the hypothesis that the end-Cretaceous mass extinction event had a major, direct influence on the diversification of today’s mammals.”

    They said their analysis of more than 40 lineages of existing mammals showed that diversification rates “barely changed” in the aftermath of the extinctions at the boundary of the Cretaceous and Tertiary periods. The transforming changes started 10 million years later and lasted until about 35 million years ago.

    Other scientists said the so-called “long-fuse model” opened a door to a better understanding of the evolutionary history of mammals and will force a re-examination of the ecological and other causes underlying the more recent proliferation of mammals.

    The international team that produced the new “supertree” of mammalian evolution was led by Olaf R. P. Bininda-Emonds of the Technical University of Munich in Germany and Andy Purvis of Imperial College in London. Other members included paleontologists, mammalogists, evolutionary biologists and other researchers from Australia, Canada and the United States.

    In another article in Nature, David Penny and Matthew J. Phillips of Massey University in New Zealand, who were not involved in the research, wrote, “Inferring a good tree of such scale is groundbreaking, and the methods will be used as a model for tree-of-life studies — whether of birds, flowering plants, invertebrate groups or other organisms.”

    They also noted that a similar analysis for birds, published recently in the journal Biology Letters, revealed that more than 40 avian lineages survived the mass extinctions. Most paleontologists now think that birds descended from dinosaurs. So in a sense, even dinosaurs in one form escaped the calamity.

    Until now, however, most paleontologists had favored a “short-fuse” model in which mammals came into their own almost immediately after the dominant reptiles vacated their habitats. Before the extinctions, most mammals were small nocturnal creatures.

    The new study confirmed and elaborated on earlier research by molecular biologists indicating that many of today’s mammalian orders originated from 100 million to 85 million years ago. The reasons for this evolutionary burst are not clear.

    Drawing on both molecular and fossil data, the researchers said they found that the “pivotal macroevolutionary events for those lineages with extant mammalian descendants” occurred well before the mass extinction and long after. They emphasized that the molecular and fossil evidence provide “different parts of this picture, attesting to the value of using both approaches together.”

    But the researchers conceded that much more research would be required to explain “the delayed rise of present-day mammals.”

    Ross D. E. MacPhee, a curator of vertebrate zoology at the American Museum of Natural History who was a team member, said that paleontologists were previously dubious of the claims by molecular biologists of such an early ancestry of today’s mammals. The fossil record of mammals in the Cretaceous period, they contended, was too sparse to support such an interpretation.

    “Now we know the ancestors of living mammal groups were there, but in very low numbers,” Dr. MacPhee said.

    “The big question now is what took the ancestors of modern mammals so long to diversify,” he continued. “Evidently we know very little about the macroecological mechanisms that play out after mass extinctions.”

  2. The Drawing Room   -   #2
    bigboab's Avatar Poster BT Rep: +1
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    These studies never have definite conclusions. That would put them out of a job. It also keeps the argument about Darwinism and Creationalism(sp) alive.
    The best way to keep a secret:- Tell everyone not to tell anyone.

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    Question Mark

    I find it funny that those in the "evolution field" are willing to concede to an idea that you and i came from a single hydrogen atom cooked up in an ancient "ooze." Yet, they cannot come to believe in the possibility that we were "created." Life comes from life...and consciousness from this. If anyone can give me an example of life starting from anything other than any other pre-included life than i am all ears.

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    j2k4's Avatar en(un)lightened
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    Quote Originally Posted by MaxOverlord View Post
    I find it funny that those in the "evolution field" are willing to concede to an idea that you and i came from a single hydrogen atom cooked up in an ancient "ooze." Yet, they cannot come to believe in the possibility that we were "created." Life comes from life...and consciousness from this. If anyone can give me an example of life starting from anything other than any other pre-included life than i am all ears.
    All ears?







    Well and succinctly put, actually.
    “Think about how stupid the average person is, and then realize that half of 'em are stupider than that.” -George Carlin

  5. The Drawing Room   -   #5
    vidcc's Avatar there is no god
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    It's funny how the "creationist" can't explain how the creator was created or show evidence.

    it’s an election with no Democrats, in one of the whitest states in the union, where rich candidates pay $35 for your votes. Or, as Republicans call it, their vision for the future.

  6. The Drawing Room   -   #6
    HeavyMetalParkingLot's Avatar Poster
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    Quote Originally Posted by vidcc View Post
    It's funny how the "creationist" can't explain how the creator was created or show evidence.
    Funny, I learned at an extremely early age that the "but little Tommy was doing it too" was not a viable defense.

  7. The Drawing Room   -   #7
    JPaul's Avatar Fat Secret Agent
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    I am baffled at the evolutionary chain which would end in a creature which was all ears. I just don't understand what niche in nature it would find, to say nothing of procreation (aural sex is not an acceptable joke here).

    I therefore take this as final and absolute proof of idiotic design.

    Quote Originally Posted by HeavyMetalParkingLot View Post
    Quote Originally Posted by vidcc View Post
    It's funny how the "creationist" can't explain how the creator was created or show evidence.
    Funny, I learned at an extremely early age that the "but little Tommy was doing it too" was not a viable defense.
    Tu quoque, you find that a lot here. I'm sure you've noticed it.
    Last edited by JPaul; 04-11-2007 at 08:44 PM. Reason: Automerged Doublepost

  8. The Drawing Room   -   #8
    vidcc's Avatar there is no god
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    Quote Originally Posted by HeavyMetalParkingLot View Post
    Quote Originally Posted by vidcc View Post
    It's funny how the "creationist" can't explain how the creator was created or show evidence.
    Funny, I learned at an extremely early age that the "but little Tommy was doing it too" was not a viable defense.
    I'm not expecting you to get where I am heading in advance, so I shall expand for you.

    those in the "evolution field" are willing to concede to an idea that you and i came from a single hydrogen atom cooked up in an ancient "ooze." Yet, they cannot come to believe in the possibility that we were "created."
    The argument is based on unconnected reasoning. Scientific studies are based on observation of evidence. If you like it's based on what the evidence points to.

    Creationism is not scientific, it's based on faith and as such cannot be proven. So unless "the creator" can be explained with evidence ( this does not include "because it's written in holy books" or "how can you look at such complexity and not believe in creationism" ), the it is not a scientific theory. So why should they believe it?

    it’s an election with no Democrats, in one of the whitest states in the union, where rich candidates pay $35 for your votes. Or, as Republicans call it, their vision for the future.

  9. The Drawing Room   -   #9
    MaxOverlord's Avatar Simplify
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    Dear vdcc...you proved my point. Scientist surely will admit that there was life at some point at which you and I "evolved" from. This life could have only come from a source of life. To think that consciousness came into effect through a "big bang" is shallow and absurd. If life was contained in that single Hydrogen atom...where did the atom come from...a life giver...or random chance. You will agree with me that there are laws that govern things. There must therefore be a law giver or if you like someone who enforces such laws. there would be no law in say the US if there were not cops and judges and people to enforce them. If no-one cared about such laws it would be impossible to enforce them. So there surely must be a law giver...life giver. God is Truth...if you believe your bible...Truth exists therefore God exists. You could argue Truth does not exist...but that statement itself is True.......If you want to believe that you came from...say...a star which according to science contains "all that is you" your welcome to it. Just remember next time your at a zoo and looking at an ape your actually looking at your great great great great grandma....lmao.

  10. The Drawing Room   -   #10
    JPaul's Avatar Fat Secret Agent
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    So, God = Judge Dredd, never thought of it that way.

    "Just remember next time your at a zoo and looking at an ape your actually looking at your great great great great grandma"

    Actually the theory is not that we are descended from apes, that appears to be a popular misconception. It's that we have common ancestors with apes. From way back and I mean really way back.

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