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Dino vision



In a message dated 95-08-22 12:57:35 EDT, you write:

>>So far as I remember eye slits are a characterisitc of nocturnal
>>hunters -- cats, crocodiles etc.  ARe any dinos thought to  fit
>>into this category?  If so they might possibly have  had slit 
>>pupis.  Any diurnal hunters would almost certainly have had
>>round pupils.
>>There are very few nocturnal birds of prey - only the owls, I
>>think.  That might be one reason few birds have modified the
>>shape of the pupil over the last 85 million years or so.
>>David
>>
>>--
>
>I never gave this much though until now! It would seem to me that we could
>draw some comparisons to the predators of the African plains. Many of the
>large carnivores are forced to hunt nocturnally due to the _heat_. The big
>cats (elliptical pupils) especially the lions are known to rest in the shade
>by day and hunt in the evening. It would then seem reasonable to conclude
>that many theropods were also nocturnal or at leasst diurnal hunters quite
>simply due to the prevailing so called _greenhouse_ climate of the
>Cretaceous. Being homeothermic/endothermic reptiles, they too would need to
>get out of the sun or overheat! The advantage of night hunting also allows
>the predators to stalk their prey more closely and shorten the preys
reaction
>time to defend itself which would come in handy when taking on an
>Ankylosaurid!  
>   Another (digression) thought. _If_ the theropods were mostly
>homeothermic/endothermic, their metabolic rates would dictate more frequent
>feeding. Based on the dinosaurs modern ectothermic relatives (reptiles) and
>endothermic relatives (the birds) metabolisms, what would be the
extrapolated
> digestive time from consumption to excretion of a typical theropod meal?  I
>have no evidence to support this but I will venture a guess of several days
>to a week at max. Thoughts anyone?
>
>                                    Regards,
>                                    Thomas R. Lipka
>                                    Paleontological/Geological Studies
>
>