New Study Shows Tyrannosaurus Rex Evolved Advanced Bird-Like Binocular Vision

Science News Online ^ | June 26 2006 | Eric Jbaffe

[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.

[RobRoy]

>>Large animals have slow birth rates. Alligator. Whale. Horse. Elephant. Etc.<<

What about really big rabbits?

[MineralMan]

"On the contrary, you have nothing to support a faster T Rex birth rate, whereas I can show that alligators breed slower than smaller reptiles."

Actually, you cannot. Virtually all reptiles breed once a year. The egg-laying reptiles lay a clutch of eggs, which then hatch and become the next generation.

Alligators lay lots of eggs in their clutch. Smaller reptiles lay fewer eggs. They all breed once a year, though. You're incorrect on all counts on this one.

Then there are the live-bearing reptiles, mostly snakes. But, that's another story.

Alligators are prolific breeders. They have to be, since most of their babies get gobbled up.

[RobRoy]

>>Essentially, you don't really know anything at all about Tyrannosaurus Rex.<<

Neither does anybody else, essentially.

Thanks for playing.

'Course, now that we have that T-Rex soft tissue, that could change in the next few years.

[Valpal1]

I have read your "paradox" quite a few times and am having problems wrapping my head around it. Is it from the bible, or a philosopher, or what?

Just don't let your head explode. LOL.

The wages of sin is death is from the bible. Some believe this means no death of any kind occurred before the fall of man. They also believe all animals were vegetarian before the fall and apparently don't count plant death???? I'm not totally clear on all points. Maybe animals only ate shed fruit and dropped leaves?

I was just answering the question. Many fundamentalists believe that the theory of evolution with it's millenia of death would negate the "wages of sin is death" explanation for the need for a savior as well as making Christ's death meaningless.

[andysandmikesmom]

Sure there were people living at the time of the dinosaur...why just read this article, about the dinosaur saddle that was found...

http://www.avantnews.com/modules/news/article.php?storyid=126

[CarolinaGuitarman]

"On the contrary, you have nothing to support a faster T Rex birth rate, whereas I can show that alligators breed slower than smaller reptiles."

Alligators don't breed slow. A T-Rex wasn't an Alligator. You have nothing to back your claim.

"D'oh! Don't you hate it when the tables are turned?!"

When that happens I'll let you know.

[CarolinaGuitarman]

"I thought the part before "blah blah blah" was good."

I'm sure you did.

[Mike Darancette]

T. rex might also have had a limiting far point of 6 kilometers, compared with the human far point of 1.6 km.

All the better to spot dead things with.

[RobRoy]

And the raccoon I saw this morning? Mainly a scavenger.

But beside the point, they may know where the eye sat, but they don't know what was IN the eyeball itself.

Also, the animal was so huge that I am surprised it could even outrun an elephant. Then again, if it's primary food was the Brontosaurus, it would have been child's play to chase them down, assuming they could even get their neck off the ground.

[RobRoy]

>>Now we are starting to see that predatory dinosaurs were smart, fast, skilled at hunting.<<

No, now some are starting to form hypotheses similar to what you state. It is still all pretty much wild speculation.

What we actually know is that there are none alive today and they were fairly large with sharp pointy teeth, which meant spinach was a problem before dates.

[RobRoy]

That is why T-rex went extinct. They all developed the gay gene and simply died out through lack of interest.

[RobRoy]

>>There were thousands and thousands of Hadrasaurs<<

Yeah, except that's not what they were called back then.

[Tokra]

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.

Your logic escapes me. Just becuase the bible says "the wages of sin is death" does not mean that death does not occur any other way.

How does sin enter into the fact that a tree gets struck by lightning, falls and dies. Did the tree "sin"?

The fact that life forms died before the evolution of mankind does NOT mean that "Christ died for nothing". I fail to see the link in your logic.

If I tell a small child "You will burn your finger if you stick it into a lighted match" does not mean that is the ONLY way he can burn his finger.

Likewise - death can occur from OTHER reasons than sin. So your whole arguement falls apart.

I have no problem in believing in God and believing in evolution. They are NOT mutually exclusive. In fact - I think that people who refuse to believe in evolution are doing God a diservice. He can do anything - including planning and creating the system of evolution. Give Him some credit!

[VadeRetro]

That's a heck of thing to have for the last image your brain ever records.

[RobRoy]

>>Lots of animals are much as they were.<<

Hey, there's one we agree on!

[Southack]

"Actually, you cannot. Virtually all reptiles breed once a year. The egg-laying reptiles lay a clutch of eggs, which then hatch and become the next generation. Alligators lay lots of eggs in their clutch. Smaller reptiles lay fewer eggs. They all breed once a year, though. You're incorrect on all counts on this one. Then there are the live-bearing reptiles, mostly snakes. But, that's another story. Alligators are prolific breeders. They have to be, since most of their babies get gobbled up."

Ahhh. Finally. The real answer is drawn out. In haste to "prove" an opponent wrong, a Darwinist actually takes a stand (pinning a Darwinist is often difficult as they shift in the wind so easily).

Alligators are prolific breeders after all, it turns out, yet the species is almost entirely unchanged for 200 million years.

Where are the mutations? Not enough time?! Too few generations?! Too few offspring?!

It is at this point that Evolutionists must claim intangibles...that prolific birth rates don't go hand in hand with *random* mutations...as if flipping a coin won't turn up random heads/tails.

And here's the kicker: that's the same point being made by Intelligent Design adherrents...that the mutations aren't random.

It's a binary proposition. Either mutations are *random* or not...and you just took a stand on the issue (now it's time for you to start blowing in the wind again).

[Southack]

"Alligators don't breed slow."

Thanks! I wanted you to take a stand.

Now, why is it that the fast-breeding alligator is so devoid of **random** mutations?

[js1138]

How do you know it is free of mutations?

[beancounter13]

I think the fundamentalists are missing the point that God made man in His own image --namely immortal. Man brought death upon himself. It is a pretty big leap to assume that all species were immortal before the fall of man.

Also, I do not follow "theory of evolution with it's millenia of death" part of your argument. Could you elaborate?

[Southack]

"How do you know it is free of [random] mutations?"

Because the species is virtually unchanged over 200 million years of rapid breeding.

"Random" wouldn't explain that track record while still being able to explain an evolutionary path of different species.