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New Study Shows Tyrannosaurus Rex Evolved Advanced Bird-Like Binocular Vision
Science News Online ^ | June 26 2006 | Eric Jbaffe

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.


TOPICS: Religion; Science
KEYWORDS: atheismsucks; atheistdarwinists; bewareofluddites; creationism; crevolist; darwindroolbib; darwinwasaloser; dinosaurs; evolution; flyingbrickbats; godsgravesglyphs; guess; heroworship; ignoranceisstrength; junk; paleontology; patrickhenrycrap; pavlovian; pavlovianevos; shakyfaithchristians; trash; trex; tyrannosaurus; useyourimagination; yecluddites; youngearthcultists; youngearthidiocy
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To: demkicker
Pinging a few atheists.

I spent two years traveling the world with a Hindu. My mother is S. Baptist, my wife is Buddhist. I am not allowed to be an atheist.

181 posted on 07/03/2006 4:35:54 PM PDT by OmahaFields ("What have been its fruits? ... superstition, bigotry and persecution.")
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To: Southack

I am not talking about selection. We agreed to talk about mutation rate. You made rather specific claims about the mutation rate for alligators. Where did you get the information?


182 posted on 07/03/2006 4:36:16 PM PDT by js1138 (Well I say there are some things we don't want to know! Important things!")
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To: CarolinaGuitarman

>>You have no clue what the mutation rates are.<<

You do?


183 posted on 07/03/2006 4:36:28 PM PDT by RobRoy (The Internet is about to do to Evolution what it did to Dan Rather. Information is power.)
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To: Al Simmons

I vote predator. I just can't see T. Rex walking by and ignoring a potential meal when ravenously hungry just because it was still alive.

However, if some other predator has already done the work, well I'd guess TR wasn't to proud to barge on into the the feast and make a selfish a pig of himself.

But I could be wrong.


184 posted on 07/03/2006 4:37:04 PM PDT by ml1954 (NOT the BANNED disruptive troll who was seen frequently on CREVO threads.)
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To: js1138
"I am not talking about selection. We agreed to talk about mutation rate."

My response in that post wasn't to you.

185 posted on 07/03/2006 4:37:21 PM PDT by Southack (Media Bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: drhogan

"Night of the Lepus"

BINGO!


186 posted on 07/03/2006 4:38:19 PM PDT by RobRoy (The Internet is about to do to Evolution what it did to Dan Rather. Information is power.)
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To: js1138
"You made rather specific claims about the mutation rate for alligators. Where did you get the information?"

No. Not "specific."

Broad. I made a *broad* claim. The species in question must have a low rate of *random* mutations. See post #151.

187 posted on 07/03/2006 4:38:42 PM PDT by Southack (Media Bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: RobRoy

Primer on mutations:

http://www.genetichealth.com/G101_Changes_in_DNA.shtml#Anchor2

What Kind of Mutations Are There?
A gene is essentially a sentence made up of the bases A, T, G, and C that describes how to make a protein. Any changes to those instructions can alter the gene's meaning and change the protein that is made, or how or when a cell makes that protein. There are many different ways to alter a gene, just as there are many different ways to introduce typos into a sentence. In the following examples of some types of mutations, we use the sentence "The fat cat ate the wee rat" as a sample gene:



Point Mutation
A point mutation is a simple change in one base of the gene sequence. This is equivalent to changing one letter in a sentence, such as this example, where we change the 'c' in cat to an 'h':


Original
The fat cat ate the wee rat.

Point Mutation The fat hat ate the wee rat.

Frame-shift mutation
Frame-shift mutations. In a frame shift mutation, one or more bases are inserted or deleted, the equivalent of adding or removing letters in a sentence. But because our cells read DNA in three letter "words", adding or removing one letter changes each subsequent word. This type of mutation can make the DNA meaningless and often results in a shortened protein. An example of a frame-shift mutation using our sample sentence is when the 't' from cat is removed, but we keep the original letter spacing:


Original
The fat cat ate the wee rat.

Frame Shift The fat caa tet hew eer at.

Deletion
Mutations that result in missing DNA are called deletions. These can be small, such as the removal of just one "word," or longer deletions that affect a large number of genes on the chromosome. Deletions can also cause frameshift mutations. In this example, the deletion eliminated the word cat.


Original
The fat cat ate the wee rat.

Deletion The fat ate the wee rat.

Insertion
Mutations that result in the addition of extra DNA are called insertions. Insertions can also cause frameshift mutations, and general result in a nonfunctional protein.


Original
The fat cat ate the wee rat.

Insertion The fat cat xlw ate the wee rat.

Inversion
In an inversion mutation, an entire section of DNA is reversed. A small inversion may involve only a few bases within a gene, while longer inversions involve large regions of a chromosome containing several genes.


Original
The fat cat ate the wee rat.

Insertion The fat tar eew eht eta tac.


DNA expression mutation
There are many types of mutations that change not the protein itself but where and how much of a protein is made. These types of changes in DNA can result in proteins being made at the wrong time or in the wrong cell type. Changes can also occur that result in too much or too little of the protein being made.


188 posted on 07/03/2006 4:39:09 PM PDT by js1138 (Well I say there are some things we don't want to know! Important things!")
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To: Southack
Broad. I made a *broad* claim. The species in question must have a low rate of *random* mutations. See post #151.

You are making a specific claim about the mutation rate for alligators. Where did you get the information?

189 posted on 07/03/2006 4:40:23 PM PDT by js1138 (Well I say there are some things we don't want to know! Important things!")
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To: demkicker
Pinging a few atheists.

I have no recollection of ever exchanging posts with you, and I don't even recognize your screen name. You are seriously mistaken, grotesquely confused, quite possibly deranged, and most certainly a discredit to this website. I would very much appreciate it if you never pinged me again.

190 posted on 07/03/2006 4:41:22 PM PDT by PatrickHenry (Free enterprise, individual rights, democracy, and evolution -- no centralized planning.)
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To: js1138
"You are making a specific claim about the mutation rate for alligators. Where did you get the information?"

No. A "specific" claim would be something akin to "alligators have 232 random mutations per generation."

A "broad" claim would something akin to "alligators have a very low rate of random mutations because the species hasn't really changed in 200 million years."

Thus ends the lesson for today on the distinctions between "broad" from that of "specific."

191 posted on 07/03/2006 4:43:52 PM PDT by Southack (Media Bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: Southack
A "broad" claim would something akin to "alligators have a very low rate of random mutations because the species hasn't really changed in 200 million years."

OK, you have made a rather broad claim. That is actually worse, unless you have a source. What is your source for the claim that alligators have a low mutation rate?

192 posted on 07/03/2006 4:46:37 PM PDT by js1138 (Well I say there are some things we don't want to know! Important things!")
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To: RobRoy

"Prove it."

I can provide evidence. Proof is for math and whiskey. The claim was that they had not changed much in 200 million years. They had, as the species that existed then are not the same as exist now.

"You do?"

I never claimed to know what the mutation rates were, as the other poster did.


193 posted on 07/03/2006 4:51:36 PM PDT by CarolinaGuitarman (Gas up your tanks!!)
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To: Tokra

to analyze Valpall's argument further: if we accepted his argument, we would also have to say that if ANYONE died before Christ was born would mean that Christ died for nothing (which clearly makes no sense); this in turn would lead to the conclusion that none of the people who died in the old testament had really died!
if his argument disproves evolution, it also disproves the old testament!


194 posted on 07/03/2006 4:52:13 PM PDT by drhogan (!)
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To: Southack
I can show that alligators breed slower than smaller reptiles.

Alligators and turtles have similar breeding cycles.

195 posted on 07/03/2006 4:52:27 PM PDT by OmahaFields ("What have been its fruits? ... superstition, bigotry and persecution.")
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To: js1138; Southack
I didn't know Alligators mutated. Does it happen a lot?

No offense JS, but he answered this over a hundred posts ago. He gave his source, and it was himself. He exercised his God given right to examine the facts and form his own opinion. Move on for crying out loud. It's not funny any more - at least not in a way flattering to you.

196 posted on 07/03/2006 4:52:34 PM PDT by RobRoy (The Internet is about to do to Evolution what it did to Dan Rather. Information is power.)
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To: CarolinaGuitarman
Proof is for math and whiskey.

Do you know where the measure "proof" came from?

197 posted on 07/03/2006 4:54:04 PM PDT by OmahaFields ("What have been its fruits? ... superstition, bigotry and persecution.")
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To: Southack
"That will be incorrect no matter how many times you repeat yourself."

No, it's true. You claim to know the mutation rates for Alligators, but you have no clue. You also made up the claim that T-rex bred really slow, something you could not in any way back up.

"(no doubt until you decide to mock me, claim you don't have enough time, or otherwise flee from this thread with your tail between your legs - which will happen)."

Keep dreaming.

"The specific mutation rate may or may not be known, but over time the specific rate must be low due to the species changing so little over so much breeding."

What *species* are you talking about?
198 posted on 07/03/2006 4:54:10 PM PDT by CarolinaGuitarman (Gas up your tanks!!)
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To: saleman

CLICK! Dang, a misfire. I'll be back soon with fresh ammo


199 posted on 07/03/2006 4:57:03 PM PDT by saleman
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To: Southack

i'm not sure that there is really a contradiction between something being random in a scientific analysis vs. being determined by God in a theological analysis.
flip an unbiased coin 50 times. the results are random in a scientific analysis. however, this would not disprove a theological analysis that claimed that God had determined the results of the coin flips.
scientific analysis cannot disprove (a good)theological analysis, and theological analysis cannot disprove (a good)scientific analysis. they are dealing with very different levels of analysis.


200 posted on 07/03/2006 4:58:04 PM PDT by drhogan (!)
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