See post #359.
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.
See post #359.
Distinction without a difference.
The same conclusion would be reached at 200,000 random mutations as for 0, 1, or 2...though the effort involved at illustrating said conclusion would be raised considerably (your goal, rather than having an honest debate).
I made my point by showing what happens at 0 mutations. Then I re-made my point by showing it again at 1 random mutation and then again at 2.
Your argument, in contrast, is so weak that you are left to merely raise the bar (e.g. to 200,000 random mutations). By that process, as soon as I showed the same result for 200,000 random mutations, you'd be so cheeky as to demand a result for 200 trillion random mutations.
Which is to say, you failed at 0, you failed at 1, you failed again at 2, and you'd likewise fail at 200,000 and 200 trillion...though you'd delay the inevitable with such inanities.
Time for bed. Night all!
Oh yeah, right. As if you have proof of that!
Rolls eyes...
That's not only incorrect, but already disproven in posts #322 and 332.
Don't play dumb. Making me repeat answers reflects poorly on your comprehension skills.
Link?
You did a deliberate word search on "alligator" on a web page ... Ridiculous.
Yes, silly of me. I should have searched for "Easter Bunny".
No, I would succeed in my point, because at that rate of mutation, selection would play a greater role. Zero, one and two are all at the same basic scale, which is why you are using such laughably small numbers. If you were honest about it, you would admit the possibility that the graph would change at higher numbers, because it is far more logical. But, as I have found that you are untruthful, even to the point of asserting people said things that they never actually said (as you did in post #330), it is obvious that you will not even admit to the obvious. How can you trust a person's arguments when those arguments are built on lies?
It would hardly have been less intelligent. Playing dumb won't score points.
Source? Link? Math? Example?
You've got bupkis. I proved my point for 0 mutations. I did it again for 1 mutation and again for 2 mutations.
All you've done is make a grand claim that somehow the "Easter Bunny" (reference to a different poster playing dumb above) would magically change your results if tried a bunch more times (e.g. 200,000).
You can't come close to showing such a result. Can't happen.
You lose.
Defend your lie in #330.
You're changing the subject. It must have dawned on you that you couldn't back up your wild-eyed "200,000" claim.
Too bad. You lose.
At least you could apologize for your falsehood, so that those who read this in the future might think better of you in your defeat...
You can tell more from a photo that the experts with all there sophisticated techniques?
Anyone who reads this thread **objectively** will see that I made a claim (mutations more important than selection) that I later proved holding true for cases of selection when there were 0, 1, and 2 random mutations.
Such a person would further see that you made the opposite claim, that selection is more important than mutations if there are 200,000 random mutations...as well as that you were unable to prove your claim.
Moreover, they'll see that you are stuck on yourself (re: some perceived lie or personal slight) rather than on the intellectual debate itself.
And there can only be one conclusion from such observations: you lost.
At least clear your conscience by admitting you made up the charge in your second sentence in #330. It's the Christian thing to do...
"T Rex was definitely a predator because it would be so LAME if it were just a scavenger."
Calvin said it. I believe it. That settles it.
Cheers!
That's incorrect. I supported my "mutations more important than selection" claim in post #322, among others.
You've supported your "selection more important than mutation" claim...mmm...nowhere. Just some wild-eyed "200,000" mutations would make it so.
That won't cut it. Support your claim or forever be seen as losing this debate.
You really need to find a used copy (now out of print, you see) of Science Made Stupid. Hilarious satire, Hugo award winner for sci-fi, and it includes just this point.
The picture of a T-rex smoking a pipe as it contemplates a chessboard is itself worth the price of the book.
Cheers!
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