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Theropod "Sunglasses" Again
Regarding the recent thread about "theropod sunglasses" - I have
some qualms about the notion.
Granted, overhanging supraorbitals may provide a bit of shading
from the sun, but the relief could only have been slight. In fact, reflected
light and glare can be just as bad if not worse than the direct source, so
frankly I see little gain from it.
Years ago (and I do mean years ago) I asked my physical anthro teacher
about brow ridges on neanderthals and whether or not they could've
performed a similar function for them.
His reply was that the brow ridges could be more indicative of enlarged sinuses
for cold weather adaption. (I haven't kept up with research in this area,
tho, so I can't say if sinuses are still considered an explanation.) Further,
that there was a direct correlation between supraorbital size and
aggressiveness. He said this correlation could be found in many species -
I do not think that dino sinuses motivated brow ridge enlargement.
One of the effects of browridges is to accent and draw attention to the eyes.
Other facial markings, with or without browridges, also do this. Many modern
animals have markings that accent the eyes (my australian shepherd has
light tan eyebrow fur over his dark brown facial fur); even some insects
exploit a strategy of using eye like markings to deter predators, so clearly
drawing attention to eyes is a widespread contemporary tactic.
Theropods certainly would've been aggressive, and so it does not seem
to find enhanced brow ridges.
What I find interesting about this scenario is the notion that this
would imply dinosaurs would've used and been affected by displays of
threat, etc., similar to that of contemporary animals (including humans).