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.
b
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.
No. But your total ignorance is showing more an more each time make another self-righteous post. Now do you fell like crawling into a hole?
WEBSTERS: fr. OE u-tor, compar.] of u-t out obs 1: to offer for sale
utter \'*t-*-r*-b*l\ \'*t-*r-*r\ vt [ME uttren, fr. utter outside, adv.,
fr. OE u-tor, compar.] of u-t out obs 1: to offer for sale 2a: to send forth as a sound 2b: to give utterance to : PRONOUNCE, SPEAK 2c: to give public expression to : express in words 3: to put (as currency) into circulation 4: to put forth or out : DISCHARGE - ut.ter.able aj
The correct word would be "into" not "in". A common mistake by the illiterate.
Placemarker
Since you consider "evolution" a religion, bashing evolution would seem to qualify you as pathetic, at least according to your definition.
Imagine. DK wanted me to offer my faith up for sale.
"pathetic" placemarker.
You need to quit since you're already far behind.
I have been on this forum for eight years without being suspended, banned or warned by a moderator.
"Where did you read this?"
From the researcher's report. From the original photograph of the specimen that had a scale on it ( a scale that is missing in the MSNBC picture). Here's some more:
http://pharyngula.org/index/science/comments/tyrannosaur_morsels/
http://www.talkreason.org/articles/DinoBlood.cfm
Yes, this is the standard explanation for the heavy flyers - that they were gliders. It does not hold water when critically evaluated. The logical hoops through which one must jump to support these kinds of theories are actually downright comical.
Thank you.
Surprisingly, we are in (partial) agreement here.
All recent evidence and analysis points to the fact that Pterosaurs, in fact, were not "gliders" but could take off on their own power (of course, all birds 'glide' when aloft to conserve energy, but I suspect that is not what you meant...
oh, and I don't think anyone who thought about it a little would describe a Pterosaur with a 40-foot wingspan, weighing 200 pounds a 'heavy flyer'.....
By the way, scientists also used to think that, based on their analysis, there was just NO WAY that a bee could manage to fly.....
I read the articles. The first seems pretty level headed and admits that we really don't know a lot yet, and then he makes an interesting prediction, due to the fact that cells have a strong "self destruct" mechanism. I liked it's frankness.
The second is just an op-ed piece making fun of professional Creationists - a pretty easy thing to do. ;)
Psst: When I want your opinion, I'll give it to you. Troll.
You have a citation for that? An actual published journal article or something? Or do you just like the sound of wind whistling through your head?
Glad to know I hit a nerve. Oh, and you're the troll, newbie.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
