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Re: attack on dinosaur--horrific video

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.

I am not entirely certain what you mean here, but I think you might be under the impression that the bony rim of the ring in owls protrudes beyond the cornea, which it does not. That said, you can actually use the ring shape, along with orbit measurements, to reconstruct avian eye shape with a high degree of accuracy (SVP presentation two years ago; I'll have to go find the reference). This, in turn, allows for reasonable assessments of acuity and sensitivity, which correlates with photocycle.

As regards avian nests: not all seabirds nest on cliffs or islands; some rookeries are rather more accessible than that. I am thinking specifically of flamingos and pelicans (though, to be fair, they do seem to like fairly hard-to-reach places; sometimes islands on lakes). I would consider many arboreal birds (esp. raptors) to use active nest protection, albeit obviously combined with elevated locations.

Oh, and just to toss this out there for fun: King Cobras and African Rock Pythons both guard nests. There are some pretty obvious reasons why they are exceptions to the usual squamate pattern, but it's worth considering. Besides, they're cool animals.



Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280 0181