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>At 02:58 PM 7/29/96 -0400, Douglas K McLemore wrote:
>>So how can one guess about the visual acuity from just a fossil?
>placement of optic lobes in a cranial cast?
Indeed. Check out Rich, T.H. and Rich, P. V. "Polar Dinosaurs and Biotas
of the Early Cretaceous of Southeastern Australia", _National_Geographic_
_Research_, 5 (1):15-53 (1989).
They detail the skull of _Leaellynasaura amicagraphica_, a hypsilophodont
dinosaur that had markedly enlarged optic lobes, as shown from an
interior cast of its skull.
As this part of Australia was well inside the Arctic circle at the time,
winter nights, while not being freezing (due to the overally increased
global temperatures in that time), would have lasted for around three
months. Any creature with poor eyesight at night would have found
foraging for food very difficult indeed.