[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Avian flight stroke origin

So close! From the title: "Assessing Arboreal Adaptations of Bird Antecedents."

AVIAN antecedents. It would have been so beautiful!


  Jaime A. Headden
  The Bite Stuff (site v2)

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 

> Date: Tue, 9 Aug 2011 19:12:06 -0400
> From: bh480@scn.org
> To: dinosaur@usc.edu
> Subject: Avian flight stroke origin
> From: Ben Creisler
> bh480@scn.org
> New in PLoS ONE (free pdf, of course):
> Dececchi, T.A. & Larsson, H.C.E. (2011)
> Assessing Arboreal Adaptations of Bird Antecedents: Testing the Ecological
> Setting of the Origin of the Avian Flight Stroke.
> PLoS ONE 6(8): e22292.
> doi:10.1371/journal.pone.0022292
> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0022292
> The origin of avian flight is a classic macroevolutionary transition with
> research spanning over a century. Two competing models explaining this
> locomotory transition have been discussed for decades: ground up versus
> trees down. Although it is impossible to directly test either of these
> theories, it is possible to test one of the requirements for the trees-down
> model, that of an arboreal paravian. We test for arboreality in non-avian
> theropods and early birds with comparisons to extant avian, mammalian, and
> reptilian scansors and climbers using a comprehensive set of morphological
> characters. Non-avian theropods, including the small, feathered
> deinonychosaurs, and Archaeopteryx, consistently and significantly cluster
> with fully terrestrial extant mammals and ground-based birds, such as
> ratites. Basal birds, more advanced than Archaeopteryx, cluster with extant
> perching ground-foraging birds. Evolutionary trends immediately prior to
> the origin of birds indicate skeletal adaptations opposite that expected
> for arboreal climbers. Results reject an arboreal capacity for the avian
> stem lineage, thus lending no support for the trees-down model. Support for
> a fully terrestrial ecology and origin of the avian flight stroke has broad
> implications for the origin of powered flight for this clade. A terrestrial
> origin for the avian flight stroke challenges the need for an intermediate
> gliding phase, presents the best resolved series of the evolution of
> vertebrate powered flight, and may differ fundamentally from the origin of
> bat and pterosaur flight, whose antecedents have been postulated to have
> been arboreal and gliding.
> --------------------------------------------------------------------
> mail2web LIVE – Free email based on Microsoft® Exchange technology -
> http://link.mail2web.com/LIVE