Re: Dinosaur Hearing, New Paper

[Dann Pigdon <dannj@alphalink.com.au>]

Danvarner@aol.com writes: 

> http://www.acoustics.org/press/153rd/dooling.html  

I've always wondered whether dinosaurs could have had external ear flaps. 
Birds and crocs both have aerodynamic and aquadynamic concerns, so there was 
always the possibility that they may have lost external ears in a process of 
streamlining the body plan. 

However, would the inability for dinosaurs (or theropods ar least, as 
mentioned in the above paper) to detect high frequency sounds mean that 
external ear flaps would not have conferred much of an improvement to 
hearing ability? It seems that amongst modern mammals the larger the ears, 
the greater the reliance on detecting high-frequency sounds (excluding 
elephants, which seem to have exapted their ears as cooling structures - 
they apparantly also hear low-frequency rumbles through their feet). 

Bats retain their ears, but they (mostly) have a huge reliance on detecting 
extremely high frequencies, so perhaps the presence of external ears is 
worth the slight loss in streamlining. Some owl species also have ear-like 
feathery tufts that may play some role in improving their hearing. 

So what's the likelyhood of any non-avian dinosaurs having had some sort of 
external ear structures (whether fleshy, feathery, or even keratinous)? Is 
the external ear size / high-frequency detection correlation even a good 
one? 

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Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.soffiles.com
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