Re: attack on dinosaur--horrific video

[john bois <jbois@verizon.net>]

I may yet give up on nest predation as an important influence on past and 
present terrestrial vertebrate communities; but I'm not going to give up on 
that one-million dollars.

Anyway...and thanks for deconfusing me...but I still have one confusal 
element...most slerotic rings seem to be in the front part of the eye, and 
set rather vertically...almost like a bony iris...but the owl's is more 
horizontal, forming a tube and seemingly leaving a gaping wide aperture in 
front for light to come in.  If this is true--and it's just an 
impression--then the structure of the owl's ring _is_ somewhat diagnostic of 
its being nocturnal.

----- Original Message ----- 
From: "Mickey Rowe;893-2446" <mrowe@lifesci.ucsb.edu>
To: <dinosaur@usc.edu>
Sent: Saturday, November 24, 2007 8:05 PM
Subject: Re: attack on dinosaur--horrific video
> For nocturnal
> animals, acuity is sacrificed for sensitivity, so there is no benefit
> to having a good focusing mechanism.  Hence, it's not that the
> sclerotic rings impede nocturnal vision, it's that the benefit they
> provide to diurnal animals is not there for nocturnal animals.
> Consequently, mutations that would reduce any and all aspects of the
> focusing apparatus (e.g., the scleral ossicles) would be neutral for
> nocturnal animals and deleterious for diurnal animals.  Thus ossicles
> would drift away in lineages of nocturnal animals.

Many thanks!