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owl ears, troodontid ears



Jaime Headden and I have been discussing the differences in ear anatomy
between owls and troodontids, in researching the suggestion made by
Castaninha and Mateus that troodontids had left/right ear asymmetry.

Castanhinha, R., and Mateus, O. (2006). "On the left-right asymmetry in
dinosaurs." Journal of Vertebrate Paleontology, 26 (Supp. 3): 48A.

A treasure in understanding asymmetry in owls is this paper:

R. A. Norberg. Skull Asymmetry, Ear Structure and Function, and Auditory
Localization in Tengmalm's Owl, Aegolius funereus (Linne)
Phil. Trans. R. Soc. Lond. B March 9, 1978 282:325-410;
doi:10.1098/rstb.1978.0014

The ear canal of owls has a posterior boundary formed by asymmetrical
structures called  called "cartilago metotica = squamoso-occipital wing"
by Norberg. Norberg's Fig. 18 shows that these wings are strongly
asymmetrical in the strigid species studied.

There is certainly nothing similar preserved in any troodontid that I'm
aware of.

I have little doubt that the asymmetry of owl ears, and their
corresponding abilities to pinpoint prey using hearing alone, are vastly
more developed than they could have been in troodontids. I suppose that,
if troodontids had any such ability, it would have been only incipient

Nonetheless, troodontids do have some reported auditory asymmetry, and
their otic regions are highly pneumatized, and these two features may
suggest special hearing abilities. It would be interesting to build either
physical or computer models to test the acoustics of troodontid skulls.