Posted on 07/03/2006 12:32:51 PM PDT by Al Simmons
In the 1993 movie Jurassic Park, one human character tells another that a Tyrannosaurus rex can't see them if they don't move, even though the beast is right in front of them. Now, a scientist reports that T. rex had some of the best vision in animal history. This sensory prowess strengthens arguments for T. rex's role as predator instead of scavenger.
Scientists had some evidence from measurements of T. rex skulls that the animal could see well. Recently, Kent A. Stevens of the University of Oregon in Eugene went further.
He used facial models of seven types of dinosaurs to reconstruct their binocular range, the area viewed simultaneously by both eyes. The wider an animal's binocular range, the better its depth perception and capacity to distinguish objectseven those that are motionless or camouflaged.
T. rex had a binocular range of 55, which is wider than that of modern hawks, Stevens reports in the summer Journal of Vertebrate Paleontology. Moreover, over the millennia, T. rex evolved features that improved its vision: Its snout grew lower and narrower, cheek grooves cleared its sight lines, and its eyeballs enlarged. ...
Stevens also considered visual acuity and limiting far pointthe greatest distance at which objects remain distinct. For these vision tests, he took the known optics of reptiles and birds, ranging from the poor-sighted crocodile to the exceptional eagle, and adjusted them to see how they would perform inside an eye as large as that of T. rex. "With the size of its eyeballs, it couldn't help but have excellent vision," Stevens says.
He found that T. rex might have had visual acuity as much as 13 times that of people. By comparison, an eagle's acuity is 3.6 times that of a person.
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T. rex might also have had a limiting far point of 6 kilometers, compared with the human far point of 1.6 km. These are best-case estimates, Stevens says, but even toward the cautious end of the scale, T. rex still displays better vision than what's needed for scavenging.
The vision argument takes the scavenger-versus-predator debate in a new direction. The debate had focused on whether T. rex's legs and teeth made it better suited for either lifestyle.
Stevens notes that visual ranges in hunting birds and snapping turtles typically are 20 wider than those in grain-eating birds and herbivorous turtles.
In modern animals, predators have better binocular vision than scavengers do, agrees Thomas R. Holtz Jr. of the University of Maryland at College Park. Binocular vision "almost certainly was a predatory adaptation," he says.
But a scavenging T. rex could have inherited its vision from predatory ancestors, says Jack Horner, curator of paleontology at the Museum of the Rockies in Bozeman, Mont. "It isn't a characteristic that was likely to hinder the scavenging abilities of T. rex and therefore wasn't selected out of the population," Horner says.
Stevens says the unconvincing scene in Jurassic Park inspired him to examine T. rex's vision because, with its "very sophisticated visual apparatus," the dinosaur couldn't possibly miss people so close by. Sight aside, says Stevens, "if you're sweating in fear 1 inch from the nostrils of the T. rex, it would figure out you were there anyway."
Stevens, K.A. 2006. Binocular vision in theropod dinosaurs. Journal of Vertebrate Paleontology 26(June):321-330.
And I suppose you think God designed cancer too?
Is right wing the guy that said God designed nothing that kills? God designed our reproductive system which results in many fertilized eggs being flushed down the drain.
No, I don't. It was an anti-evolutionist that asserted God hasn't designed anything that kills.
I'm confused. Many anti-evolutionists point to the bacterial flagllum as something that was specifically designed. Michael Behe, the official spokesman for the Discovery Institute, testified under oath that he thought the designer was God.
But the primary activity of the flagellum is killing infants and children. I'm confused about what anti-evolutionists believe.
I think you have demonstrated by you conduct that you worship Satan. At least you serve him well.
I believe in God Almighty. I don't claim to have answers to all questions and refuse to believe that theism and evolution is an either/or choice.
Pathetic comeback. It seems to be a habit that after Omaha Fields gets backed into a corner, you come out calling names in his defense. Are you his mommy? Why don't you MYOB?
I'm just a passerby who has noticed the source and effect of your behavior. Are you ashamed of serving Satan?
Well, you can keep on passing by because you are a nut to say that I serve Satan. LOL!
I'm just observing that no decent person would want to associate with whatever is inspiring your behavior tonight.
Since you can't say what you belive in, you must be agnostic.
Who crowned you the behavior judge? You, sir, are obnoxious! Get over yourself.
I believe that OmahaFields did not really say he could not say what he believed, but rather that he chose not to share that piece of informtion, with the person who was asking for it...so your assumption that he must be agnostic, is faulty...
Pathetic comeback. It seems to be a habit that after demkicker gets backed into a corner, you come out calling names in his defense. Are you his mommy? Why don't you MYOB?
I've asked a simple question to someone who continually refuses to answer. Since you don't seem to believe in God or Satan, why are you trying to yank my chain and change the subject? Why should anyone be afraid to state their beliefs? And more importantly, why do you jump in to defend OmahaFields?
I'm yanking your chain because you are an asshole, and are embarrassing religion.
I dont understand why you think it is any of your business, what someone believes regarding God, or Satan, or what religion they may or may not belong to...some folks may chose not to answer your questions, and some folks may gladly answer your question...If someone states, that they dont wish to answer, it would just seem wise to let it go...
And I'm just observing that your are a Buttinski and I don't approve of your behavior tonight.
One thing is certain. You are very unforgiving, especially after receiving an apology.
Nice. Did you get your vocabulary from Sunday School this morning?
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