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Dinosaur Sight.



jbmiller@fn.net wrote:

>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.

Marion
avimort@aurora.cc.monash.edu.au