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