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Re: And Your Bird Can Sing-Mesozoic theropod vocalizations?





On Tue, Nov 10th, 2009 at 1:21 PM, "T. Michael Keesey" <keesey@gmail.com> wrote:

> On Mon, Nov 9, 2009 at 5:11 PM, Dann Pigdon <dannj@alphalink.com.au> wrote:
> >
> > Roaring requires thickened vocal cords. I don't think birds actually have 
> > vocal cords, although
> that
> > doesn't necessarily rule out their presence in dinosaurs.
> 
> Aren't vocal cords/folds a mammalian (or therian?) synapomorphy?
> 
> Birds have syringes (plural of syrinx, not the medical needles)
> instead, although I'm not sure how widespread they are throughout the
> crown group. Do palaeognathes have them? If so, at least some
> stem-avians probably had them, too.

Cassowaries lack a syrinx, however ostriches apparently have them. Ratities in 
general seem to 
lack functional syringeal muscles (as do storks and New World vultures) , but 
it would seem they 
had them ancestorally. They can only grunt and hiss, although resonating 
throats can turn grunts 
into booms (as with the emu).

The number of muscle pairs the syrinx has seems to determine how complex the 
song is. Birds 
with just one or two pairs of syringeal muscles tend to have very simple 
vocalisations (goose 
honking, duck quacking, etc). Oscine passerines have taken syringeal complexity 
to the extreme, 
with eight pairs of syringeal muscles (two extrinsic and six intrinsic).

Here's an interesting PDF I found on the subject:

http://udel.edu/~gshriver/pdf/Communication.pdf

-- 
_____________________________________________________________

Dann Pigdon
GIS / Archaeologist                Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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