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.
For such an advanced and noble creature, its such a shock it didn't evolve the capability to survive the giant-fricken'-meteor-thing.
Here is a recreation os "Sue" from the Field Museum in Chicago that illustrates the point of this article NICELY....
How far apart they are? Where do you get that?
And if you don't have the eyes, you compare the skull in other ways.
Oh, but they did drive cars! Of course, the fuel they used in those cars contributed to "global cooling", and they could not adapt to the resulting climate change. /s
I suspect we just pinged a few of the same people....(my what I troublemaker I've become on this topic...;>)
Less often than elephants and aligators.
Tyrannosaurus rex's cheek grooves (below the eye sockets) and narrow snout cleared its sight lines, giving it impressive vision, according to a new study.
Here is a recreation os "Sue" from the Field Museum in Chicago that illustrates the point of this article NICELY....
Sue seems to be modified just a bit. Her eyes are less covered.
If you take the reproductive rate of alligators or Komodo dragons as a ballpark estimate, how many generations do you think would occur in, say, 30 million years? How many generations do you suppose it takes to get a teacup poodle from a line of wolves, or from a pack of mongrel dogs?
IIRC, the vision "problem" that the T-Rex had in Jurrasic Park had to do with the fact that the gaps in the DNA-sequence had been filled with the DNA of some species of frog, meaning that the latter-day T-Rex had a few defects/enhancements. Maybe this scientist should have payed better attention to the quickie primer on DNA-recovery techniques given to the visitors at the beginning of the movie.
Most predators will scavenge if they are given the opportunity, so it's not an either/or argument. I tend to think of the T-Rex as the analog of the Great White Shark. He cruises the periphery of the pack dino, ambushing an individual animal for a chunk of meat. After the victim has bled-out, he returns to scavenge the carcass (assuming other T-Rex's don't drive him/her away. Pack-hunting is a possibility, but I don't know if there's much evidence for it.
The more we know, the better we are. Plus, we have to keep exercising our brains or they might atrophy.
30 million years would only apply if the mutations waited that long. When do the modified T Rex skulls appear in the timeline? At the beginning of the T Rex species, middle, or at extinction?
YEC SPOTREP
Is it a T Rex?
My point in discussing dogs is that one shouldn't confuse variation in size and bone length with large changes in the genome. Small changes in regulatory genes account for the difference between wolves and chihuahuas.
Just in case you really want to know and aren't asking a rhetorical question.
It's "the wages of sin is death" paradox. If death is the result of sin (and sin came from man) then all the millenia of death from evolution prior to man can't exist or if there were millennia of death prior to man then the "sin caused death" isn't true which means Christ died for nothing and our sin is not expiated by it.
So in order to keep your head from exploding you have to make a choice. Maybe God is right and he really did create all things in 6 literal days and created light even before the sun, moon and stars..... or Man is right and life on earth evolved over time and God had nothing to do with it.
If you understand both points of view you see that they are mutually exclusive as belief systems
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.