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early dinosaur body-size transitions due to trait evolution's passive processes

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  • Stephan Pickering
    R.B. Sookias, R.J. Butler, R.B.J. Benson, 2012. Rise of dinosaurs reveals major body-size transitions are driven by passive processes of trait evolution. Proc.
    Message 1 of 2 , Feb 2, 2012
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      R.B. Sookias, R.J. Butler, R.B.J. Benson, 2012. Rise of dinosaurs reveals major body-size transitions are driven by passive processes of trait evolution. Proc. Royal Soc. London B279 + Data Supplement IN PRESS. ABSTRACT. A major macroevolutionary question concerns how long-term patterns of body-size evolution are underpinned by smaller scale processes along lineages. One outstanding long-term transition is the replacement of basal therapsids (stem-group mammals) by archosauromorphs, including dinosaurs, as the dominant large-bodied terrestrial fauna during the Triassic (approx. 252–201 million years ago). This landmark event preceded more than 150 million years of archosauromorph dominance. We analyse a new body-size dataset of more than 400 therapsid and archosauromorph species spanning the Late Permian–Middle Jurassic. Maximum-likelihood analyses indicate that Cope's rule (an active within-lineage trend of body-size increase) is extremely rare, despite conspicuous patterns of body-size turnover, and contrary to proposals that Cope's rule is central to vertebrate evolution. Instead, passive processes predominate in taxonomically and ecomorphologically more inclusive clades, with stasis common in less inclusive clades. Body-size limits are clade-dependent, suggesting intrinsic, biological factors are more important than the external environment. This clade-dependence is exemplified by maximum size of Middle–early Late Triassic archosauromorph predators exceeding that of contemporary herbivores, breaking a widely-accepted ‘rule’ that herbivore maximum size greatly exceeds carnivore maximum size. Archosauromorph and dinosaur dominance occurred via opportunistic replacement of therapsids following extinction, but were facilitated by higher archosauromorph growth rates. 
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      STEPHAN PICKERING / Chofetz Chayim ben-Avraham
      Torah G-ddess Jew Skeptophiliac / Starfleet Yeshiva Apikorus Spiritist
       
       
      THE DINOSAUR FRACTALS PROJECT
      2333 Portola Drive # 4
      Santa Cruz, California 95062-4250
       
       
      IN PROGRESS: Mutanda Dinosaurologica: in memory of Samuel Paul Welles (9 November 1909--6 August 1997)
      IN PROGRESS: Dialects of a synaesthetic heart: poetics for Faline Pickering (23 January 1949--24 August 2008)
      IN PROGRESS: Alfred Russel Wallace's KING KONG: the semioptics of Willis O'Brien
       
      PARTNER IN THE UNIVERSE TO: FALINE PICKERING, MY BELOVED QUANTUM AQUARIUS
      BROTHER IN THE UNIVERSE TO: KITTY CALEENE PICKERING, MY SISTER
      MEMBER 13853: Society of Vertebrate Paleontology
       
      One concept corrupts and confuses the others. I am not speaking of the Evil whose limited sphere is ethics; I am speaking of the infinite. ...Reality is not always probable, or likely. -- JORGE LUIS BORGES
      You never know what's comin' for you. -- QUEENIE in ERIC ROTH'S  The curious case of Benjamin Button
      What if G-d didn't say it? -- BART EHRMAN
      Seek the sacred with the ordinary. Seek the remarkable with the commonplace. -- REB NACHMAN OF BRESLOV
      G-d is all that exists, but not all that exists is G-d. -- R. MOSHE CORDOVERO

    • clarence_sonny_williams
      This is hard to believe, that body size is not under strong selection pressure but rather passive processes of trait evolution. Large size is too costly to
      Message 2 of 2 , Feb 2, 2012
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        This is hard to believe, that body size is not under strong selection
        pressure but rather "passive processes of trait evolution." Large size
        is too costly to have not a strong adaptive reason for its evolution.
        Moreover, why does a clade-distinctive characteristic provide evidence
        for this? If size was under strong selection pressure, wouldn't you
        expect the clade to share the same size parameters?

        Yours truly,

        Confused in the shadow of Pike's Peak

        --- In evolutionary-psychology@yahoogroups.com, Stephan Pickering
        <stefanpickering2002@...> wrote:
        >
        > R.B. Sookias, R.J. Butler, R.B.J. Benson, 2012. Rise of dinosaurs
        reveals major body-size transitions are driven by passive processes of
        trait evolution. Proc. Royal Soc. London B279 + Data Supplement IN
        PRESS. ABSTRACT. A major macroevolutionary question concerns how
        long-term patterns of body-size evolution are underpinned by smaller
        scale processes along lineages. One outstanding long-term transition is
        the replacement of basal therapsids (stem-group mammals) by
        archosauromorphs, including dinosaurs, as the dominant large-bodied
        terrestrial fauna during the Triassic (approx. 252â€"201 million
        years ago). This landmark event preceded more than 150 million years of
        archosauromorph dominance. We analyse a new body-size dataset of more
        than 400 therapsid and archosauromorph species spanning the Late
        Permianâ€"Middle Jurassic. Maximum-likelihood analyses indicate
        that Cope's rule (an active within-lineage trend of body-size increase)
        is extremely rare,
        > despite conspicuous patterns of body-size turnover, and contrary to
        proposals that Cope's rule is central to vertebrate evolution. Instead,
        passive processes predominate in taxonomically and ecomorphologically
        more inclusive clades, with stasis common in less inclusive clades.
        Body-size limits are clade-dependent, suggesting intrinsic, biological
        factors are more important than the external environment. This
        clade-dependence is exemplified by maximum size of Middleâ€"early
        Late Triassic archosauromorph predators exceeding that of contemporary
        herbivores, breaking a widely-accepted ‘rule’ that
        herbivore maximum size greatly exceeds carnivore maximum size.
        Archosauromorph and dinosaur dominance occurred via opportunistic
        replacement of therapsids following extinction, but were facilitated by
        higher archosauromorph growth rates.Â
        >
        > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        > STEPHAN PICKERING / Chofetz Chayim ben-Avraham
        > Torah G-ddess Jew Skeptophiliac / Starfleet Yeshiva Apikorus Spiritist
        > Â
        > Â
        > THE DINOSAUR FRACTALS PROJECT2333 Portola Drive # 4
        > Santa Cruz, California 95062-4250
        > stephanpickering@...
        > Â
        > website:Â http://groups.yahoo.com/group/paleo_bio_dinosaur_ontology
        > http://groups.google.com/group/Torah_G-ddess_Jews
        > Â
        > IN PROGRESS:Â Mutanda Dinosaurologica: in memory of Samuel Paul
        Welles (9 November 1909--6 August 1997)
        > IN PROGRESS:Â Dialects of a synaesthetic heart: poetics for Faline
        Pickering (23 January 1949--24 August 2008)
        > IN PROGRESS:Â Alfred Russel Wallace's KING KONG: the semioptics of
        Willis O'Brien
        > Â
        > PARTNER IN THE UNIVERSE TO: FALINE PICKERING, MY BELOVED QUANTUM
        AQUARIUS
        > BROTHER IN THE UNIVERSE TO: KITTY CALEENE PICKERING, MY SISTER
        > MEMBER 13853: Society of Vertebrate Paleontology
        > Â
        > One concept corrupts and confuses the others. I am not speaking of the
        Evil whose limited sphere is ethics; I am speaking of the infinite.
        ...Reality is not always probable, or likely. --Â JORGE LUIS BORGES
        > You never know what's comin' for you. --Â QUEENIE in ERIC ROTH'S
        Â The curious case of Benjamin Button
        > What if G-d didn't say it? -- BART EHRMAN
        > Seek the sacred with the ordinary. Seek the remarkable with the
        commonplace. -- REB NACHMAN OF BRESLOV
        > G-d is all that exists, but not all that exists is G-d. -- R. MOSHE
        CORDOVERO
        >
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