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Re: How archosauromorphs beat out therapsids

Lead author Roland Sookias discusses this project more at:


On Wed, Feb 1, 2012 at 10:45 AM, Heinrich Mallison
<heinrich.mallison@googlemail.com> wrote:
> Interestingly, much of what is verbatim quotes in the press is not
> touched upon in the paper at all. And that stuff comes across, in the
> press, as being results of the study, when in fact it is old news.
> Me = not happy.
> ___________________________________
> Dr. Heinrich Mallison
> Abteilung Forschung
> Museum für Naturkunde - Leibniz-Institut
> für Evolutions- und Biodiversitätsforschung
> an der Humboldt-Universität zu Berlin
> Invalidenstrasse 43
> 10115 Berlin
> Office phone: +49 (0)30 2093 8764
> Email: heinrich.mallison@gmail.com
> _____________________________________
> Fere libenter homines id quod volunt credunt.
> Gaius Julius Caesar
> On Wed, Feb 1, 2012 at 5:48 PM, Ben Creisler <bcreisler@gmail.com> wrote:
>> From: Ben Creisler
>> bcreisler@gmail.com
>> Here's the official citation:
>> Roland B. Sookias, Richard J. Butler and Roger B. J. Benson (2012)
>> Rise of dinosaurs reveals major body-size transitions are driven by
>> passive processes of trait evolution.
>> Proceedings of the Royal Society B (advance online publication)
>> doi: 10.1098/rspb.2011.2441
>> http://rspb.royalsocietypublishing.org/content/early/2012/01/31/rspb.2011.2441.abstract
>> The pdf of the data supplement is free:
>> http://rspb.royalsocietypublishing.org/content/suppl/2012/01/31/rspb.2011.2441.DC1/rspb20112441supp2.pdf
>> 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.
>> ========
>> Two news story links about a new study of how archosauromorphs beat
>> out therapsids and reached huge size.
>> The official article has not been posted yet on the Proceedings of the
>> Royal Society B site:
>> http://news.discovery.com/animals/how-dinosaurs-got-so-big-120131.html
>> http://news.sciencemag.org/sciencenow/2012/01/the-secret-of-dinos-success.html?ref=hp