Re: Dinosaur Vocalization

[Sam Barnett <sam.horus@gmail.com>]

Even if they didn't have avian vocalisation, crocodilian vocalisation
is most impressive.  One way or another I'm sure the Mesozoic was a
bizarre and unique soundscape.

On Saturday, December 4, 2010, Sim Koning <simkoning@msn.com> wrote:
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>      I'm currently reading through Phil Senter's 2008 paper 'Voices of the 
> past: a review of Paleozoic and Mesozoic animal sounds'. So far I'm finding 
> it very interesting and informative, but I have some problems with some of 
> his arguments for the lack of vocalization in dinosauria. I'm not a 
> scientist, so I'm hoping that others on this list can help point out some key 
> points that I may have missed. The argument seems to be as follows: there is 
> lack of osteological indicators for pneumatization of the humerus in 
> non-avian dinosaurs and since there are osteological indicators for other air 
> sacs in dinosaurs, but not for the clavicular air sac, then it is unlikely 
> that non-avian theropods possessed clavicular air sacs. I think there may be 
> several logical flaws with this claim:
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> 1. If ontogeny recapitulates phylogeny in bird embryos, then as the paper 
> suggests, we may presume that clavicular air sacs evolved late in 
> ornithodiran history. However, using the same reasoning, we may presume that 
> air sacs evolved before they invaded the bones. Therefore, the lack of 
> osteological indicators for a particular air sac is not strong evidence for 
> its absence.
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> 2. There may not have been sufficient selective pressure for theropods to 
> evolve highly pneumatized humeri prior to the evolution of flight. The 
> forelimbs of theropods were used primarily in the acquisition of prey, so it 
> may have been more beneficial for (most) theropods to retain solid furculae 
> and forelimb bones. The possibility that flying pterosaurs were the only 
> other archosaurian group outside aves that evolved pneumatic humeri may be 
> evidence of this.
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> 3. Since air sacs of dinosaurs probably evolved before they invaded bone, the 
> ancestors of Aerosteon may have had fully formed clavicular air sacs and 
> therefore a syrinx. Considering this, I find it more parsimonious that the 
> common ancestor of Aerosteon and aves possessed a clavicular air sac rather 
> than evolving independently in allosauroids and aves. If this was the case, 
> then we may use phylogenetic bracketing to presume that most taxa between 
> Aerosteon and aves may have possessed a syrinx and so may have been capable 
> of avian style vocalization.
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>   Those are a few things that came to mind while reading that section of the 
> paper. I apologize if this subject has already been heavily addressed on the 
> mailing list.
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> Simeon Koning.
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