That's incorrect. The alligator is little-changed in 200 million years.
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.
Mutations may or may not be random. Selection is what shapes populations, and selection is not random.
even if they HAD been there, they would have all been EATEN!!!
Selection is not random in breedstock either, yet man has never created a new species in thousands of years of selective breeding and intentional exploitation of random mutations.
So unintentional nature can acheive what intentional man can not?
well, if you're ever hunted by a t-rex, you now know that you should leave, rather than standing still so it can't see you.
this knowledge will save many people's lives!
the cars have all rusted by now, but the excellent vision of the t-rex probably evolved because it was needed for driving.
(the dinsaurs with bad vision were unable to get drivers licenses, so they couldn't get dates, didn't reproduce, and they all died out.)
yeah--dinosaurs developed good vision so they could watch movies!
i think i got it now!
Thousands of years is an eyeblink, and the varieties produced by selective breeding are as distinctive as those that separate most wild species.
also, they started playing "chicken", and many died in car accidents.
the high rate of drug and alcohol use also led to many accidents and needless deaths.
also, the claws on their front legs were not good for holding onto the steering wheel, and many lost control of their cars and ran off steep mountain passes.
finally, the foolish t-rex's bought poorly made foreign cars, which folded up like accordions when they crashed into apatosauruses.
the meteor got all the rest, except for a few that mutated into birds.
That's incorrect. The alligator is little-changed in 200 million years.
"I think it's because alligators are perfectly suited to the environment to which they are intended. Same with mosquitoes, flys, etc. Sorry for interrupting. Go ahead"
And yet, your fellow Darwinist claims that alligators have lots of mutations. Go figure. Each Darwinist spins a different way, contradicting each other. Who woulda thunk it?!
Change in a population is the result of selection, not mutation rate.
That would be like claiming that dogs/wolves are as genetically distinct as goats/elk.
What makes you think I'm a Darwinist? BTW, I'm not.
Selection merely culls a population. Selection is not in dispute. Whether a mutation is random (e.g. Evolutionary) or due to some level of outside bias (e.g. Intelligent Design), the resultant species/hybrid still is subject to Selection.
There is no controversy regarding Selection.
The controversy surrounds the mutations (random or biased).
"That doesn't make them devoid of [random] mutations. You said they were, which is wildly incorrect."
On the contrary, a little-changed species represents an insignificant number of random mutations over 200 million years.
That's a misleading claim. Sure, a population can thrive or decline without ever having a mutation...but...for evolutionary theory to even be a potential explanation of a specific origin of a species, the species must have some random mutations as well as remain subject to Selection (e.g. not protected in a lab).
Based upon your posts, whatever you claim to be is a distinction without a difference to Darwinism, though no doubt you **feel** differently.
Label yourself, then. I'm disinterested.
Not at all. You have consistently ignored everything I have posted regarding the difference between genetic variation and morphology. Classifications of fossils are based on morphology, but it is obvious from dog breeds that larges variations in size and shape do not indicate large genetic differences. Classification of fossils will always present problems.
I have been pointing out that the assertion that breeding or artificial selection has produced changes in animals great enough to be considered division as separate species if we did not know their history and could not analyze their DNA. The people claiming we have not produced new species have no basis for this claim. They are comparing apples and oranges -- creatures for whom we have a few fossilized bone specimens vs creatures for whom we have detailed pedigrees.
The fact is that artificial selection can produce rapid morphological change in populations.
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