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Re: Question: Why did birds lose their teeth?



From: Ben Creisler
bcreisler@gmail.com

I would have to reread this paper to know if it addresses the issue,
but this paper or the refs listed may offer some information.

Louchart A, Viriot L. (2011)
>From snout to beak: the loss of teeth in birds.
Trends Ecol Evol. 2011 Dec;26(12):663-73.
doi: 10.1016/j.tree.2011.09.004. Epub 2011 Oct 4.

Pdf available for free at:
http://www.researchgate.net/publication/51705217_From_snout_to_beak_the_loss_of_teeth_in_birds

Abstract
All living birds are toothless, constituting by far the most diverse
toothless vertebrate clade, and are striking examples of evolutionary
success following tooth loss. In recent years, an unprecedented number
of Mesozoic birds have been described, illustrating the evolution of
dentition reductions. Simultaneously, major advances in experimental
embryology have yielded new results concerning avian edentulism.
Reviewing these lines of evidence, we propose hypotheses for its
causes, with a prominent role for the horny beak during development. A
horny beak and a muscular gizzard functionally 'replaced' dentition
for food acquisition and processing, respectively. Together with
edentulism itself, these features and others contributed to the later
success of birds, as a result of their high performance or additional
functionality working in concert in these complex organisms.


On Mon, Mar 10, 2014 at 2:00 PM, Jason Brougham <jaseb@amnh.org> wrote:
> Tooth loss has happened repeatedly in widely divergent vertebrate families.
>
> In the Mesozoic there were both toothed and edntulous basal Avialae,
> toothed and edentulous enantiornithines, and toothed and edentulous
> ornithoracines. The only surviving lineage (crown group birds) were from
> among the edentulous ornithothoracines.
>
> Thus, it may be more of a founder effect than an adaptation.
>
>
> Jason Brougham
> Senior Principal Preparator
> American Museum of Natural History
> jaseb@amnh.org
> (212) 496 3544
>
>
>
>
>
> On 3/10/14 4:54 PM, "Mike Habib" <biologyinmotion@gmail.com> wrote:
>
>>Martin (and list):
>>
>>I am having trouble finding that specific reference, as well, though a
>>bit of quick math shows that tooth loss in birds can¹t remove significant
>>weight because the entire hard tissue skeletal system (teeth included)
>>only accounts for about 25-35% of total body mass, of which half is
>>water. By way of example, the total dry mass of both humeri in a
>>mid-sized bird (390-500 gram range) ranges from about 0.7% to 1.2% of
>>total mass. The teeth would presumably make up less mass than that of
>>both entire humeri. The potential loss of mass from losing teeth is
>>dwarfed by the body mass changes from simply burning fat and muscle in
>>flight. During long migrations, some birds lose 50% of their body mass.
>>Under those conditions, the lost of teeth is practically rounding error.
>>
>>‹Mike
>>
>>
>>Michael Habib
>>Assistant Professor of Cell and Neurobiology
>>Keck School of Medicine of USC
>>University of Southern California
>>Bishop Research Building; Room 403
>>1333 San Pablo Street, Los Angeles 90089-9112
>>
>>Research Associate, Dinosaur Institute
>>Natural History Museum of Los Angeles County
>>900 Exposition Blvd, Los Angeles, CA 90007
>>
>>https://plus.google.com/+MichaelHabib/about
>>biologyinmotion@gmail.com
>>(443) 280-0181
>>
>>
>>On Mar 10, 2014, at 7:16 AM, Martin Baeker <martin.baeker@tu-bs.de> wrote:
>>
>>> Dear all,
>>>
>>> I once learned that losing teeth was a weight-saving measure and thus
>>> a flight adaptation. There is this reference stating this  as a
>>>possibility
>>>
>>>http://www.newscientist.com/article/dn18248-early-birds-may-have-dropped-
>>>teeth-to-get-airborne.html#.Ux3HhdsjulM
>>>
>>> However, I seem to remember that there was some study showing that
>>> birds actually do not lose signifcant weight by replacing teeth with
>>> beaks - if anybody has a reference on this, I'd be grateful.
>>>
>>> Thanks a lot,
>>>
>>> Martin.
>>>
>>>                   Priv.-Doz. Dr. Martin Bäker
>>>                   Institut für Werkstoffe
>>>                   Technische Universität Braunschweig
>>>                   Langer Kamp 8
>>>                   38106 Braunschweig
>>>                   Germany
>>>                   Tel.: 00-49-531-391-3065   <===  NEW phone number!
>>>                   Fax   00-49-531-391-3058
>>>                   e-mail <martin.baeker@tu-bs.de>
>>>                 
>>> http://www.tu-braunschweig.de/ifw/institut/mitarbeiter/roesler1
>>>                         http://www.scienceblogs.de/hier-wohnen-drachen
>>
>>
>>
>