how do scientists know that a T-Rex only saw movement?

Question

and that the raptor hunted in packs etc etc
all from fossils?

Answer 1

Let us start with Jurassic Park. It's a story written by Michael Crichton, which was then made into a film by Steven Speilberg. In the book, Dr Alan Grant does not know that T-Rex can only see something when it moves. He learns it, when the animal turns to face him & he freezes in fear. However, since 1991, American Palaeontologist Professor John 'Jack' Horner of the Museum of the Rockies, in Bozeman, Montana, U.S.A. has argued that T-Rex was simply a scavenger, who was far too heavy to run & may have used its huge size to grab a quick meal off of smaller carnivores. American Palaeontologist Peter Larson, of the Black Hills Institute of Geological Research in Kansas, U.S.A. believes, along with American Palaeontologist Bob Bakker that T-Rex was practically the ultimate killing machine. On Earth for almost 170 million years, surely something big & deadly would evolve. Larson's book, Rex Appeal, explains virtually everything there is to know about Tyrannosaurus. In actual fact, his book also gives full explanations on the evidence they have on the habits of Tyrannosaurs, & even shows pictures of each T-Rex skeleton, which was discovered by his team in Dakota. The evidence weighs so much, it's almost too good to be true. The skull of T-Rex, along with many other carnivorous dinosaurs, was covered with hinges. Like a snake, Tyrannosaurs & other large theropods, were able to dislocate certain parts of their jaws. Tyrannosaurus is also known to have had the most powerful jaws of any known dinosaur, with the ability of biting with as much as 1.5 tonnes of force, which is enough to crush a car. The eyes of a Tyrannosaurus, were also forward pointing, which is found in all highly evolved predators, such as eagles, cats, & wolves etc. All active predators have forward pointing eyes. It helps to judge distance when pursuing a target. Rex Appeal is perhaps the best reference you can find anywhere on a T-Rex. It explains absolutely everything about it. Tyrannosaurus is known all too well these days, for having all the bio-mechanics of a perfect predator. Now for the raptors. The evidence of pack hunting behaviour has been identified at various localities in Montana. Deinonychus antirrhopus, was discovered in the Lower Cretaceous Cloverly Formation in South Central Montana, in 1964, by Palaeontologist Professor John Ostrom of Yale University. He was on an expedition with a group of students. Among these students was Bob Bakker. Bakker is now the world's most famous Palaeontologist. He is best known for his controversial theory, which suggests that Dinosaurs were warm blooded animals. Nobody seriously believed him at first, but the evidence for it is mounting. Deinonychus, along with Jurassic Park star Velociraptor was a type of carnivorous dinosaur called a Dromaeosaur. Dromaeosaurs are characterised by all sorts. On the 3rd toe of each foot, is a large sickle claw, which was always held off the ground when walking or running. The Deinonychus numbered three in total, when they were found. They were found with the remains of a herbivorous dinosaur called Tenontosaurus. However, Dromaeosaurs were also coated with fine downy feathers, of which the question as to 'why' is still being debated & studied. They also had tails that were held aloft & stiffened by bony rods. Perhaps the best evidence however, for their relation to birds, is a wish bone, known otherwise, as a Furcula. They are also characterised by a half-moon shaped bone in the wrist, which is found also in Archaeopteryx; the earliest known bird. This bone would have enabled a wide range of movements, such as 'sweeping' & 'folding' movements. The Dromaeosaurs are also known to be among the most intelligent of all dinosaurs. Wolves are more or less a modern example. In packs, they hunt down very large animals, those of which are much larger & more powerful than themselves. By hunting in packs, a coordinated attack pattern, which is evident in virtually all pack animals, the Dromaeosaurs, such as Velociraptor, Utahraptor, Deinonychus & Dromaeosaurus etc would have been capable of bringing down very large & powerful prey.

Answer 2

The scientists know that a T-Rex only saw movement and that the raptor hunted in packs etc etc all from fossils by studying the space between the eyes of the T-Rex, the distance which connects the eyes to the brain and according to their height, the space between their feet, the size of the olfactive cavity. And for the raptors they certainly have found fossils of raptors around a prey so they can affirm that raptors hunted in packs.
But to know the truth about how the dinosaurs lived and hunted it would be better to find a live specimen but it will not happen... so all the study rest on theories.
I have always asked myself why the scientists thought that all (if not many) dinosaurs were covered with scales... because, for my part, I think that those animals were not all scaly as it is thought but certainly hairy too... as many animals we can see today... Or maybe was it too hot on those times so that they didn't need to cover themselves more !

Answer 3

> how do scientists know that a T-Rex only saw movement?
We know they didn't see only movement. That was a blunder by Michael Crichton in his book Jurassic Park.
Seeing only movement works pretty well for an animal that eats its food in one gulp. Big carnivores take more than one bite to eat their food. Their food doesn't become invisible between the time they take the first bite and the time they take the second.

> raptor hunted in packs
We can find fossil nests of some dinosaurs. If we find a lot of the same type of nest together, we might assume that the animal lived in a herd or pack.

Answer 4

The T-Rex only seeing movement is something of a myth, I think, and was based on the fact that some reptiles have vision of that sort. As far as I know, it's only really been said in Jurassic Park (then this view was disagreed with in the 2nd book).

As for raptors hunting in packs, that one's due to their size, mainly. There isn't actually any fossil evidence that confirms they were pack hunters, though.

Answer 5

From watching Jurassic Park. Natural History according to Steven Spielberg and Michael Crichton.

Answer 6

Well, they don't know for sure, but these are educated guesses. These are extrapolations they make based on models provided by living species. Zoologists examinate extant animals and look for rules which aply to a certain group etc. Paleontologists then use this rules to imagine how the extinct species would have behaved or what their physical features would have been. This is quite complicated science and, as stated above, doesn't neccessarily be the truth.

Answer 7

Your question is somewhat misleading.

T-Rex could see everything just fine; otherwise, they would have had a lot of trouble chasing their prey if they couldn't see trees, rocks, etc.

Like most carnivores, T-Rex was probably color blind. It had no need to see greens, reds, or golds; it only needed to see what was moving, as movement indicated life, and therefore possibly something to eat. Despite the pitiful size of T-Rex's brain, it was able to discern things swaying in the breeze versus food running away or staying to fight.

Conversely, herbivores (such as Brontosaurus) could see everything in vibrant color, as they needed to discern what plants were healthy and therefore worth eating.

Answer 8

They don't know that.

It's a fictional conceit from Jurassic Park based on the notion that this is a common characteristic to some reptiles.

It's possible, though.

Answer 9

It is amazing what they can work out tho you need to understand the nature of science as science theory is not fact just the best idea at the time. Science theory sometimes becomes fact we know the earth is round that is a fact but how it was created is science theory. So they don`t know for sure but have a good idea thats why science is the pursuit of truth.

Answer 10

Wasn't that just Jurassic Park? Pure conjecture by Michael Crichton, just to add a plot twist.