Nobody can follow?! Weren't you the "genius" who went searching for "alligator" or "Easter Bunny" on a Crocodylia web page?! Surely there are more intelligent readers on this thread than that...
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.
Since nobody can follow what y'all two are going back and forth with, who really cares a RA who won or lost. If you have the time to waste, have at it.
Nobody can follow?! Weren't you the "genius" who went searching for "alligator" or "Easter Bunny" on a Crocodylia web page?! Surely there are more intelligent readers on this thread than that...
Cheers!
I didn't get involved in your discussion with that other guy but seeing (above) how you twist and and make personal attacks I really don't see how he put up with you that long. Do you have a real life?
I like your reasoning. Here's another couple of relevant questions to consider, to which I haven't the foggiest clue of the correct answer.
Did the sauropods commonly held to be prey for T-rex & other large predators travel in herds?
Were they hunted by lone T-rex assailants, or by packs?
When a sauropod was brought down, how much meat was left over for scavengers to pick over? Just possibly--I don't know, nor am I even confident in my guess--a lone T-rex might gorge and leave XYZ tons of meat on the bones. OTOH, a pack/herd/pod/gaggle/wtf of velociraptors, or several packs, might successively pick the bones clean shortly after the kill. That brings to mind another question.
Do we know the "pecking order" for scavengers following the kill of one of the sauropods?
If you had the occasional XYZ tons of meat lying around in heaps, and T-rex was a scavenger, but near the top of the pecking order, then I guess getting the requisite protein wouldn't be as much of a challenge.
If there are any true paleo's around here, though, they should be able to tell me in a matter of microseconds just how bad of a rectocranial inversion I have, even to have asked those questions.
I defer to their judgement...
Cheers!
A lot of the fraternity / sorority types couldn't. But in principle you are correct.
However, the original disputation was whether or not T-Rex was scavenger or active predator. I haven't yet heard anyone seriously suggest that on the whole T-Rex was primarily a prey species. Except possibly with respect to the Calvinosaur.
Cheers!
Nope,never crossed my mind.
"Random" wouldn't explain that track record while still being able to explain an evolutionary path of different species.
Possible slight confusion on your part, Southack, or maybe I'm missing *your* point.
Let us assume for the nonce, and oversimplifying so I don't have to type an encyclopedia, 200 million years ago, three different mama alligators.
Let's call this "Goldicrocks and the three genes".
Mama alligator A has mutations that are "too big"--the changes in her progeny are actively harmful (trying for a five-chambered heart and missing, or diplocaudus syndrome: tails on both ends).
Her family tree hits the wood chipper right away.
Mama alligator B has mutations that are "too small"--they don't make any significant changes over time. Her progeny are found today, and called "alligators". BFD.
Mama alligator C has mutations that are "just right"--they are large enough to accumulate over time, but not enough to render the descendants blessed with them non-viable. Her descendants are with us today in the form of certain attorneys and time-sharing salesmen. Alas! Since they have changed so much, even though their bloodline runs true, we don't *realize* (or cannot prove conclusively) that they really descended from alligators.
Point here is, once you *have* mutations which change the identity of the species, you will by definition not recognize them as the same species. The presence of an unbroken chain of the species does not preclude "side branches" -- think also of versions of software code...esp. in object oriented languages such as java. The problem is to establish (if you will) a definitive "chain of custody" to prove the genetic inheritance. This cannot be done in the sense of signed receipts for alligator semen, frozen alligator embryo farms, etc., but it *can* be done indirectly--by comparing strings of oft-conserved DNA, tracking the presence of DNA insertions from retroviruses, looking at mutations held in common across species boundaries, etc.
Someday if I ever get the time I'll write something up about the annoying "special pleadings" with which evos and creos get on each others' nerves and and up playing "less filling, tastes great" to the great loss of bandwidth on FR.
Cheers!
African or European swallow?
I don't...AIEEEEEE!!!
Monty Python Cheers!
You played dumb. Now you're acting shocked that anyone would dare mock you for looking dumb. You're lashing out. My comments clearly hit home with you...and frankly, you had it coming based upon your earlier bad behavior.
Ahhh, but it *is* a BFD that a group/order/species/animal that propagates prolifically hasn't *itself* changed in millions of years. We've had Ice Ages. Droughts. Floods. Heat waves. Yet it hasn't changed.
Hmmm...
You may think that if you wish, but frankly, I have already forgotten what your comments were. By the time I finish this post and sign off, I won't even remember your handle. Cheers.
Smoking!? No wonder T-Rex went extinct. ;-)
St Augustine..One might ask why brute beasts inflict injury on one another, for there is no sin in them for which they could be a punishment, and they cannot acquire any virtue by such a trial. The answer, of course, is that one animal is the nourishment of another. To wish that it were otherwise would not be reason- able. For all creatures, as long as they exist, have their own measure, number, and order.
Fr. John Echert : The food chain that exists among the animals is amoral, that is, it is not an issue of morality since an animal does not have an eternal soul created in the image of God. And so, even had there not been the sin of Adam or in the time prior to the original sin, animals may very well have consumed other animals in accord with the nature they were endowed with by the Creator. Man, however, would have been protected from such violence by a special grace, among those given to Adam and Eve which protected them from suffering and death and provided them a harmony with God, self, each other and nature. And while our first parents lost the preternatural graces they had been endowed with prior to their sin, so far as I know we would not say that their human nature was changed, though it was weakened and without the assistance of grace following sin. And it was only after the catastrophic flood that God allowed men to consume the meat of animals, though not the lifeblood itself.
*So, it isn't necessarliy the case that animal deaths prior to the Fall negate the truth of Original Sin while at the same time supplying probitive evidence for the Hexameron Thesis
So, it isn't necessarily the case that animal deaths prior to the Fall negate the truth of Original Sin nor does the amoral nature of animals eating one another necessarily make a positive contribution to the Hexameron Thesis.
It still is a poorly written sentence. I think I should just have an Anchor Steam beer and blow-up something. Happy Independence Day
I sincerely apologize if I offended you. Now, will you answer my question?
HAHAHAHAHA! How did you find that?
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