When they are lucky enough to find a complete or nearly complete skeleton, they can simply put it together to find the height. If many bones are missing, than they make educated guesses regarding the size and shape of the missing bones, based on similar dinosaurs. Then they can construct a skeleton of these bones and the known bones to get a pretty good guess as to its height.
Their fossils (bones).
Scientists get information about dinosaurs from fossils and they are able to trace DNA and find out how dinosaurs looked, ate, hunted and lived.
Scientists have no way of knowing what sounds dinosaurs could make.
Birds, which are not just considered descendants of dinosaurs; they are dinosaurs.
I know about dinosaurs and their habitats from reading about them. Scientists learn about dinosaurs and their habitats by studying fossils.
How
Yes. Many scientists nowadays consider birds to be dinosaurs. Animals such as pterodactyl were not actually dinosaurs.
Dinosaurs have long been extinct, making it impossible for scientists to work with living dinosaurs.
The height of dinosaurs is difficult to measure. The height is dependant on the type of the dinosaur in question and it's posture (the way it is standing at a particular moment).
Scientists know about dinosaurs because they have got archaeologists to go around the world and dig up the ground to find the remains of dinosaurs. Many archaeologists have found the remains of dinosaurs and you can go to your local museum and nearly every museum has a dinosaur part with real dinosaurs bones and remains.
Scientists that study dinosaurs are called paleontologists.
no, they are considered to be an actual type of reptile.