"T-Rex vision is based on movement. If you stand perfectly still, he won’t be able to see you."
Of course we’ve all heard this in Jurassic Park, and this morning I heard it again while my daughter was watching Dora (and we all know Dora is very scientifically accurate!)
Is this true? It sounds like an urban legend.
And if it is true, how could we possibly know this from studying fossils? We don’t have any T-Rex eyes to study.
If you read the book, the reason given for dinosaur vision is that they “filled in the gaps” in the DNA by taking some from frogs, and frogs are wired to respond to changes in motion rather than to simply views of objects themselves. This was too complex to try to present in a swift action movie, so they simply planted the idea early on, in the Montana segment, by having sam Neill’s character toss out a line about how the Velociraptor vision worked that way, then had him say the same thing about the T. Rex later when they’re being attacked.
I’ll bet Jack Horner and the other advisors were giggling their heads off.
It makes for an interesting scene, and suggests that dinosaurs are more complex and deeper than we thought (as do the poisonous saliva of the Dilophosaur and its neck frill), but there’s not a lick of evidence for it, and I doubt if any palaeontologist believes it.
One thing I do like is that they show the T. Rex with a round pupil (and one that reacts to light), rather than a slit pupil. Slit pupils may look cool, but I have reasons to believe it wasn’t used by a carnivore as big as T. Rex. Consider, for instance, that lions and tigers, big cats both, nevertheless have round pupils.
And as for the idea of “filling in” dino DNA with amphibian DNA – HAH!
BrundleRex.
Their biggest limitation was never being able to get their glasses on straight owing to those tiny, little arms.
Which of course explains the popularity of these during the Jurrasic.
Oh, yeah – and T. Rex and Triceratops were Cretaceous, not Jurassic. Horner and company must’ve been perpetually biting their hats.
You know how those fashion fads persist over time.
I believe you are confusing two separate technical issues presented in the book. The theory Dr. Grant presents about T-Rex vision is based on paleontological evidence and comparing the T-Rex to modern animals with similar cranial structures, etc. I believe it was in fact a new theory at the time Crichton wrote the book.
The frog-DNA issue is presented later.
No; his character, Grant, specifically says Velociraptor vision DOESN’T work that way. He describes his scenario with the proposed victim (the ugly little kid) standing still because he assumes Velociraptor sees by movement, “like T-Rex,” but then gets eaten anyway because they’re more clever than that.
Gotta disagree with you RickJay. My recollection is that, although they bring in ther frog DNA when they’re talking about the reconstruction, they do use that explanation for why the T. Rex sees that way. There’s no way you can glean information about the T. Rex motion vs. non-motion viewing from palaeontological evidence. It’s spinning dramatic action for the book (and movie out of some far-fetched science.
As for the Montana scene, my point about his introducing the point about the T. Rex only seeing moving things was introduced at that point, as I said. It’s foreshadowing. I might’ve gotten it wrong about velociraptos being that way, but that’s minor, and not the point I was making.
Is the calorie content of three humans, two of them immature, worth the energy investment required to chase them for extended periods? There were apatosauruses and triceratopses on that island - why was the T-Rex wasting time and energy running after morsels?
I’ve got to agree with Cal on that. I’ve never heard the slightest suggestion in the paleontological literature that T-rex vision would work like that of a frog, and since the closest relatives of T-rex, crocodilians and birds, are perfectly capable of seeing non-moving prey there’s no reason to think T-rex couldn’t. T-rex also had some degree of binocular vision.
Do frogs in fact have motion-based vision?
More broadly, isn’t motion sensitivity more of a spectrum than an either/or? I know, just from formerly owning a cat, that they’re more sensitive to movement than we are, presumably because they hunt small prey. If you want to get a cat’s attention, it helps to move something–it helps with a human, too, but it seems like even more so for a cat. And the instinct of a hamster, if you frighten it, is to freeze, so they must think that their predators have motion-based vision. But of course, that’s not to say that a cat can’t see a stationary object.
I believe there is some debate as to whether TRex hunted live prey, no? If they did, wouldn’t it be likely that their vision was more motion-sensitive than otherwise?
One of those morsels was Laura Dern.
I understand, Mr. T-Rex… I understand.
Hey Cal-
You recollection, in addition to being incorrect according to my recollection, does not even make logical sense. If the T-Rex as bred for Jurrasic Park has limited vision due to the frog DNA, then how would the doctor know about it at the beginning of the movie, before he has heard of Jurassic Park or even contemplated cloning dinosaurs?
:smack:
Your recollection.
Carry on…
In the book, during the T. rex attack on the road, Grant realizes that the T. rex couldn’t see him:
Unfortunately, after a quick skim, I couldn’t find the explanation for that…
I do recall the frog DNA being implicated (it was also explicitly mentioned as the cause for the supposedly-all-female dinosaurs beginning to breed), but I can’t find the exact passage in the book. I also seem to recall the idea was retracted in the sequal, The Lost World.
In the movie version, the whole “vision based on movement” thing was just presented as fact, without explanation.
It is, perhaps, also worth noting that in the book, it is explained that they did occassionally use avian DNA to fill in the gaps:
After Wu checks his records, he finds that they did, in fact, use frog DNA.
So it’s not the case that they only used frog DNA to fill in DNA gaps, at least in the book. In the movie, I think they just went for all-frog DNA for filling in the missing pieces.
In the book, he didn’t, and it wasn’t a tenet of Palaeontological belief, either. It emerged that the T. Rexes in Jurassic Park had this frog-based limitation on its vision because of the frog DNA, but he didn’t know that until they observed the bahavior in the T. Rex. For the m,ovie, they simplified it by making the weird motion-based T. Rex vision thing a well-known fact so they could introduce it early. I guess they thought it would be too much information for the audience if they threw it all at them at once.
It may be illogiocal, but it ain’t my doing – blame Crichton and the script.
Actually, there’s even more in the script that smacks of hasty revision. They make a big deal out of using frog DNA to fill in gaps in the dino DNA (just as in the book), but then they fail to use this detail to explain the two unexpected dinosaur behaviors that result. One is the motion-based vision. The other is the way some dinosaurs change sex spontaneously – just as some lower life forms do under stress – this allowing the dinosaursd (who were all cloned as females) to obtain males and mate. In the book this is made clear. In the movie they simply pass it off asc “Life Will Find a Way”. I don’t recommend you try that explanation when all of humanity consists of ten guys on a desert island.
To sum up:
Book: Dinosaurs reconstructed with frog DNA, which gives them frog motion-sensitivity (and insensitive to unmoving things), and allows some of them to change sex. Nobody’s aware of these features until they encounter them among the living dinosaurs.
Movie: T. rex is known to be insensitive to stationary items, but tracks movement. It’s simply asserted that this is known. Later on, it’s discovered that some dinosaurs are reproducing, but it’s not explained how. They do make a deal about the dinosaurs having gaps filled in with frog DNA, but no conclusions or results are drawn from this (just like the lysine deficiency, which gets mentioned in the film, but has even fewer consequences tha in the book).
The practical result of filling in Dinosaur DNA wwith frog DNA seems to me likely to produce unworkable creatures, at best. The only plausible reason for Crichton introducuing the idea is to get a toehold of plausibility for both the motion vision and the sex change. Otherwise, you’d think they’d use reptile or bird DNA, as something a lot close than frog. But it’s a real reach.
Regarding the movie, as has been noted, Dr. Grant does bring up the issue of T-rex vision in the Montana scene, but does not give a reason for it:
From IMDB
For what it’s worth, I was correct about the diea being retracted in The Lost World:
That passage also implicates Grant as theorizing that the tyrannosaur could not see him, not because of frog DNA, but because of the rainstorm during that initial attack in Jurassic Park. I’m not sure if this is a case of revisionism on the part of Crichton, or if that’s what he really had in mind regarding Grant’s explanation in that academic corner of his mind, and somehow readers made the non-implicit connection with the frog DNA thing.
In the movie, the frog DNA is used to conclusively explain the gender change. If not for this, there would have been no reason for the movie to even bring it up.
The wiring of a frog’s retina enables it to detect small moving objects at that level; it has “bug detectors.” In higher vertebrates that integration is done at the level of the brain, rather than in the retina. Frogs can detect both small and large moving objects (prey and predators) and large stationary objects (rocks, water); they are not so good at detecting small stationary objects. Most reptiles and higher vertebrates have no problem with the latter.
Some allege T-rex was a scavenger (unlikely IMO for ecological reasons). If so it might be less sensitive to movement (although there is no actual reason to suppose it was, since this is not true of other scavengers), but of course then it wouldn’t be chasing people around.