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Re: attack on dinosaur--horrific video



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!